Copper Development Association Inc.
1. General Product Information
Copper is a roofing, flashing, gutter and wall cladding material with an extremely long history of proven performance. It combines adequate strength with superior malleability and resistance to atmospheric corrosion with a desirable self-generating patina finish. Due to the potential for long service life, copper is often selected by building owners and architects who value life cycle financial benefits over low, initial material cost.
The following sections provide generalized guidance. We encourage professionals designing, installing or inspecting copper systems to refer to industry standard guides such as Copper in Architecture – Design Handbook for more thorough information.
1.1 Packaging and Storage
1.2 Roofing Categories
1.3 Product Manufacturers
1.4 Industry-Specific Standards, Codes Requirements, and Compliance
1.1 Packaging and Storage
Packaging should not trap moisture or allow moisture to penetrate the coil or sheet. Desiccants inside the package are often used when the products are to be stored for longer periods of time.
While the material is being stored and prepared for installation, it must be protected from moisture and should not be left unprotected at any stage of preassembly. Care should be taken to prevent oils, handprints, dirt and debris from contaminating the surface. Stray acids or fluxes should also be neutralized, and exposure should be limited. Proper installation techniques are required, and following the design manuals previously mentioned should provide a long-lasting roof system.
1.2 Roofing Categories
There are many proven design methods for copper roofing systems. These include, in general order of commonality:
- Standing seam.
- Batten seam.
- Flat seam (unsoldered/high slope and soldered/low slope).
- Shingles.
- Horizontal seam.
- Custom (a combination of above methods).
Although through-fastened (such as corrugated) copper roofing systems are a possibility, they are rare and typically avoided because the metal is penetrated in the process, causing a potential leak point that will only grow when the roof material is subject to thermal stress.
The design methods for copper roofing systems are listed in “Copper in Architecture – Design Handbook,” Roofing Systems.
1.2.1 Roof Pitch Limitations
A minimum slope to shed water is required for copper roofs. Minimum slope is determined by climate, roofing system, roof geometry and other factors. General slope guidelines are listed in the “Copper in Architecture – Design Handbook,” Table 8.1A, Table 8.1B, and Table 8.1C.
In some cases, copper roofs may have been installed before building codes were in place, or may be subject to variances for historical buildings. For further information, refer to the manufacturer instructions and the authority having jurisdiction.
1.2.2 Substrates and Finishes
The most common substrate for copper is wood, usually 3/4-in. plywood. Other solid substrate materials may be suitable, but industry standard recommendations or specific roof panel manufacturer installation specifications should be considered to ensure adequate fastener pull-out strength and compliance with uplift requirements.
Sheet copper is generally installed with a bare, mill-finish surface and allowed to weather naturally. Alternatives include:
- Factory, pre-patinated copper – a product with chemically induced weathering.
- Metallic coated copper – a product coated at the factory with tin or tin/zinc alloy metal.
1.3 Product Manufacturers
Copper roofing panels, flashing, gutters and wall cladding are produced by a large number of brand name manufacturers. Such products are also often locally produced by skilled sheet metal roofing contractors.
1.3.1 Current Manufacturers
1.3.2 Industry Trade Associations
The trade association for copper roofing products is Copper Development Association, Inc.
1.4 Industry-Specific Standards, Codes Requirements, and Compliance
Sheet copper for roofing systems is typically produced to meet requirements in ASTM B370: Standard Specification for Copper Sheet and Strip for Building Construction.
1.4.1 Wind
Wind uplift code requirements and enforcement vary greatly by state and region. Roofing and gutter components shall be installed to meet design load limitations as determined by the ASCE 7-10 Components and Cladding (C&C) requirements.
Copper roofing has been tested to meet the most stringent wind uplift requirements, such as the Underwriters Laboratories (UL) 580 test procedure. Generally, design of copper systems for buildings potentially subject to higher wind loads should include:
- Sturdier edge connections.
- Thicker copper.
- Narrower panel width.
- More frequent attachment of cleats/fasteners.
1.4.2 Fire
The copper portion of a roof assembly does not support combustion. The assembly fire classification shall meet the minimum code requirements as determined by the authority having jurisdiction.
2. Installation Guidelines
Refer to the manufacturer installation instructions or the Copper in Architecture – Design Handbook for details.
2.1 Roof Weights/Re-roofing
2.2 Roof Support/Sheathing Materials Options
2.3 Underlayment Options
2.4 Installation Methods
2.5 Accessory Items
2.6 Attachment of Accessories
2.7 Climatic Recommendations
2.8 Eave Treatments
2.9 Ventilation
2.10 Anti-Ponding
2.11 Ridge Treatments
2.12 Valley Flashing Treatments
2.13 Penetrations
2.14 Insulation
2.15 PV/Solar Panel Installations
2.1 Roof Weights/Re-roofing
The weight of a copper roof varies depending on the style of roofing, thickness of copper, seam spacing, and attachment cleat spacing. The weight per 100 sq ft is roughly between 190 lb (narrow, batten seam, 20-oz copper panels) and 123 lb (wide, standing seam 16-oz copper panels). Copper roof physical characteristics shall meet the minimum code requirements as determined by the authority having jurisdiction.
When re-roofing a building, older roofing materials and underlayment should be removed, and the substrate should be inspected and replaced if necessary.
2.2 Roof Support/Sheathing Materials Options
The most common substrate for copper roofing is wood, usually ¾-in. plywood. Other solid substrate materials may be suitable. Refer to industry standard recommendations or the specific roof panel manufacturer installation specifications to ensure adequate fastener pull-out strength and compliance with uplift requirements.
2.3 Underlayment Options
The most common underlayment for copper roofing is 30-lb felt underlayment (specified to the latest ASTM standards covered with a red rosin paper slip sheet. The rosin paper helps prevent adhesion on the back side of the copper and allows for thermal movement. Fully adhered, ASTM D1970 underlayment products are compatible with a copper roof system, provided a high-temperature rating (refer to the manufacturer) and the use of rosin paper. Substitutes for traditional 30-lb felt have recently become popular; however, long-term temperature, ultraviolet exposure, and other tests have not yet been standardized for these products. Since this research is ongoing, refer to the manufacturer of these products to determine if the product will function for the life of a copper roof.
2.4 Installation Methods
Proper design and installation techniques will commonly allow a copper roof to function properly for over 100 years. A number of installation manuals are available, and traditional-style standing seam, batten seam, or flat locked copper roof systems are installed using these time-proven manuals. The Copper Development Association’s Copper in Architecture – Design Handbook and Copper and Common Sense are just two of the North American manuals which help determine proper seam types for various slopes, fastener spacing, expansion and contraction concerns, and many other critical details including flashing and gutter design that need to be considered.
2.4.1 Fasteners
Most fasteners in a properly installed copper roof are all concealed, except in rare conditions. These include both nails or screws which hold fixed or expansion cleats to the roof deck. Ring shank copper or 300 series alloy stainless steel nails are common. 300 series stainless steel or brass screws are also suitable. Using non-compatible fastener materials can result in galvanic corrosion to the fastener in contact with the copper. Cleat spacing should be at least 12 in. on center for standing and batten seam systems with two fasteners used per cleat. A solid, smooth, nailable substrate with proper pull-out strength is required.
2.5 Accessory Items
Snow-retention, solar, ventilation, and air-handling systems are often added onto the roof. Provisions that allow the copper to expand and contract normally must be accounted for. Contact the accessory supplier for item specifications.
2.6 Attachment of Accessories
Mechanically attached accessories are most often used on copper roofing systems. Some components can be soldered to the roof deck. Ensure that accessory items and attachment methods are galvanically compatible with copper.
2.7 Climatic Recommendations
Copper can be used in all weather conditions. However, underlayments are rated for different temperatures, which must be verified for compatibility for their intended use with copper roofs. Refer to the manufacturer of the underlayment for temperature ratings.
2.8 Eave Treatments
Eave treatments vary slightly depending on the system, but generally secure the copper roof system while allowing for thermal movement.
Two examples of eave treatments are provided in the “Copper in Architecture – Design Handbook,” 8.2D. Eave Details.
2.9 Ventilation
Backside ventilation is not required. However, proper ventilation of the building envelope may be advantageous and should be reviewed by a design professional with experience in such issues.
2.10 Anti-Ponding
A minimum slope to shed water is required for copper roofs. For flat-locked and soldered low-slope copper roof decks, the minimum slope is 0.125-in. rise per 12-ft run. Slope requirements for steep-slope copper roof systems are considerably higher, and they should never pond water. The “Copper in Architecture – Design Handbook,” Table 8.1A, Table 8.1B, and Table 8.1C., provides basic slope requirements for copper roofing systems.
2.11 Ridge Treatments
Ridge treatments are dependent upon the roof design. Details for various designs can be found in Copper in Architecture – Design Handbook and Copper and Common Sense, or in the manufacturer installation instructions.
2.11.1 Fastening
Refer to Section 2.4.1 for details.
2.11.2 Ventilation
Copper systems do not require backside ventilation to prevent corrosion. Some building owners, however, prefer to ventilate the system substrate to help prevent ice damming or to increase energy efficiency. Although other options are possible, the “Copper in Architecture-Design Handbook” presents a ventilated ridge flashing in Section 9.4B
2.12 Valley Flashing Treatments
As valley flashing collects water and geometry dictates a valley is at lower slope than adjacent roof planes, proper system design and installation becomes even more important. Examples showing the importance of valley flashing treatments are provided in the “Copper in Architecture – Design Handbook,” Section 8.2G.
2.13 Penetrations
Roofing penetrations are always an area of concern. It is very important to ensure that the penetration is watertight, while allowing thermal movement. Exact penetration design varies depending on the type of penetration. For example, a pipe boot penetration centered in a standing seam roof panel is considerably different from a large skylight that may span many seams. Examples of roofing penetrations are provided in the “Copper in Architecture – Design Handbook,” Section 9.9.
2.14 Insulation
There are no special design considerations for incorporating insulation within a copper roof system. If insulation is installed above the structural decking, ensure that the outer surface is not compressible. Cleats must be attached to or through a smooth planar surface.
2.15 PV/Solar Panel Installations
Photovoltaic or solar panel systems may be installed on copper roofing. As with all such attachments, it is very important to ensure that the mounting system does not restrict thermal movement and water and/or debris drainage and that adjacent materials are galvanically compatible.
2.15.1 Fastening
Refer to Section 2.4.1 for details.
2.15.2 Flashing
Flashing techniques for photovoltaics vary greatly depending on the system design. As with other flashing, it is very important to ensure that the flashings do not restrict thermal movement and water and/or debris drainage of the metal roof. (Refer to Section 2.12.)
3. Repair and Maintenance Guidelines
3.1 Natural Aging Vs. Damage
3.2 Repair or Replacement
3.3 Blending New and Old
3.4 Locating Product Sources
3.5 Disposal/Recyclability of Products
3.6 Dents and Paint Flaking
3.7 Color Fading
3.8 Fastener Failure
3.9 Maintenance/Upkeep Guidelines
3.10 Expected Product Life Cycle
3.1 Natural Aging Vs. Damage
Copper roof systems often remain intact for over 80 years. Older details may have been used for these roofs and care should be taken to understand the original system. Although initial inspection can be done from ground level with binoculars, inspections are best done at roof level.
In most environments, copper will show a progression in color as it ages, ranging from bright shiny copper to black, gray, brown, and eventually green. This type of aging, known as patination, is the result of surface oxidation and the formation of copper oxide. As a copper surface matures, the oxide becomes thicker, which generally provides a natural brown or green oxide. When copper is newly installed, the surface appearance can be changed significantly with exposure to acids, fluxes, cleaning solutions, dirt and oil. Most of these changes are short-lived and the natural oxidation process will continue. Fully patinated copper will often require 25 years of exposure to the elements on a sloped surface. Patination/oxidation is aided by a sloped surface versus a vertical surface, along with higher humidity and temperature. Copper in arid regions will normally mature to a deep brown color. See the weathering color chart for a rough pictorial of typical oxidation in a northeastern U.S. climate. Time frame and ultimate color tone vary based on climate and exposure.
A proper inspection of a copper roof should include examination of the roof edges including ridge and hip areas. One area of concern is the connection of the roof to fascia or gable end. Separation in this area may indicate damage. Obvious signs like panels that have been pulled up off the roof deck can be spotted; the roof deck itself could also be damaged from debris. It is important to look at the roof deck assembly from inside the building. Proprietary copper roofing systems and panel systems may have different failure modes, and the original designing manufacturer should be consulted for specifications and inspection techniques.
It is difficult to damage a properly installed copper roof system; however, it does happen. Physical damage from maintenance, moving heavy objects, creating additional roof penetrations, dissimilar metal reactions, alterations which restrict thermal movement, and other events can cause damage and leaks. As an example, standing seams are often flattened or bent, but can often be straightened. However, the base of the seam may be subject to cracking after multiple cycles. If a puncture occurs, a small area can be deoxidized, tinned and soldered using a copper patch.
3.2 Repair or Replacement
If damage is limited to a few panels on batten and standing seam systems, it can often be repaired by removing and splicing in new panels. Taking advantage of copper’s malleability, seams can be opened relatively easily, and panels can be removed in the damaged areas, where new underlayment, roof panels, and proper fasteners can then be installed.
On soldered seam systems, do not attempt to simply resolder the seams. Old copper can be soldered; however, the material must be fully deoxidized, pre-tinned, and fluxed properly. This generally limits the ability to repair larger areas of the roof and replacement of those areas should be considered. For flat locked and soldered roof areas, replace the roof sections where a natural slope transition or expansion battens are present.
3.3 Blending New and Old
Distributors will not be able to match the color or oxidation of an existing roof with new bare and bright copper; given time, the new material will oxidize based on its environment. Some specialty products are available from manufacturers that attempt to mimic the oxidation process. Other alternatives for changing copper’s color include various chemicals which can be applied on-site to turn copper a range of colors. Because of the number of variables involved, chemically induced patinas are prone to lack of patina adhesion, excessive staining of adjacent materials, and inability to achieve reasonable color uniformity over large surface areas. These potential shortcomings should be considered when specifying such treatments. Unless the affected area is small, it is generally best to allow new material to weather naturally.
3.4 Locating Product Sources
Copper sheet and coil, along with copper-related accessories like nails, cleats and 300 series stainless steel fasteners, can be found at building product distributors that handle other roofing related products. A list of mills that produce sheet copper can be found at www.copper.org.
3.5 Disposal/Recyclability of Products
Architectural copper, generally produced from recycled product, is fully recyclable when the roof or wall system has reached its end of life. Copper is one of the most recycled architectural products and retains its value over time. Copper material should be segregated and free from other debris, and returned to a local scrap dealer for credit, which is usually determined by the COMEX or LME trading value at that time.
3.6 Dents and Paint Flaking
Generally, minor dents do not pose a problem for copper. If the surface patina is disturbed, it will re-oxidize with time and blend back into a natural appearance. While inspecting dents, look for any areas of penetration that may have been caused by a pointed or sharp object. If there are areas of penetration, replace or repair that section.
3.7 Color Fading
Natural oxidation and exposure to the elements will change the appearance of copper over time. Changes usually occur more quickly in a warm, moist environment and less quickly in arid environments. Low-slope surfaces will tend to oxidize more quickly than high slope or, slower yet, a wall cladded with copper. These color/patination changes will never be uniform like a painted material, and areas of a roof facing north versus south, areas subject to runoff, and areas with vegetation will have different appearances that are most noticeable in the early stages of oxidation. A weathering color chart shows the natural progression of color changes from bright shiny copper color (red, brown, or tan) copper to a fully patinated green.
Copper in very arid regions or areas not exposed to rainfall may only reach a deep brown/black color, perhaps with limited amounts of dark green.
3.8 Fastener Failure
Fasteners used on properly installed copper roof and wall cladding systems are concealed. Signs of fastener failure are usually panel uplift or pull off. The most common reason for failure is the use of less noble fasteners that corrode. If the roof is not severely bent or destroyed, proper copper, brass or 300 series stainless steel fasteners can be used to refasten the copper panels to the roof deck in accordance with the design manual instructions. Deck material that has been compromised by moisture or other deterioration must be replaced in most cases.
3.9 Maintenance/Upkeep Guidelines
Standard maintenance practice requires periodic inspection for loose or damaged flashings, clearing the area of standing water, and removal of debris, especially that from gutters and associated drainage components. With proper installation and design, very little additional maintenance is required for the life expectancy of a copper roof or wall cladding system.
3.9.1 Cleaning Valleys
Valley areas should be kept clear of debris, and any foreign objects should be removed.
3.9.2 Algae, Moss, Dirt, Foliage
Copper roofs prevent the formation of algae and moss. Dirt and foliage should be removed from the roof surface and gutter areas, followed by a clean water rinse. Typically, any staining on the copper roof will blend into the surrounding area over time; however, additional cleaning with non-chlorinated Tri Sodium Phosphate (TSP) may speed up the process. Caution should be taken to lightly apply the TSP so the patina is not disturbed. A low-pressure power wash could be tested in a small area prior to treating a large area. This should be followed by a clear water rinse.
3.9.3 Power Washing
A low-pressure power wash should not disturb a copper surface’s current patina and may allow for removal of some dirt and debris. If some stains remain after washing, additional cleaning with non-chlorinated Tri Sodium Phosphate (TSP) can be done, followed by a clear water rinse.
3.9.4 Walking on Product
Metal roofing should not be considered a primary roof access walkway. If it becomes necessary to walk over the top of the roofing, footwear should be clean and non-scuffing.
3.9.5 Roof Penetrations and Skylights
Proper flashing is required on copper roofs around roof penetrations and skylights. Find basic details for roof penetrations at www.copper.org, or in the manufacturer installation instructions.
3.9.6 Flashings
Flashing is one of the more critical areas of copper roof system design. Find basic details for roof penetrations at www.copper.org,, or in the manufacturer installation instructions.
3.9.7 Recoloring of Roof
Unlike many other types of metal roofing, copper is rarely painted, rather its protective finish occurs naturally through patination. Painting of copper is very dependent on ambient temperatures and surface preparation. If painting is needed or desired, consult with the paint manufacturer for the most recent product offering and directions.
Occasionally, field patination is requested. There are many chemicals that can be found online and applied to a copper surface to change its color. Most of these treatments provide varying results, depending on the surface preparation, ambient temperature and application technique. Any field applications should be fully tested, or come with references of previous successful applications prior to starting the project.
Some copper sheet and coil manufacturers can provide pre-patinated brown or green copper, under various trade names. Other reputable metal treatment and restoration firms will field patinate the copper, providing an array of appearances. Field patination, especially over large areas, rarely approaches the same appearance of a naturally weathered roof.
3.10 Expected Product Life Cycle
Properly installed copper roof and wall cladding systems can last well over 100 years, withstanding hail, wind, heat and many other environmental conditions. Copper’s corrosion resistance, formability, ease of repair, and light weight make it a reliable choice for many projects.
4. Damage Issues
4.1 General Information
4.2 Identifying Damage
4.3 Determining Hail Damage
4.4 Determining Wind Damage
4.5 Determining Fire Damage
4.6 Determining Cold Weather Damage
4.1 General Information
4.1.1 Product Identification
The product is normally identified on the package shipped from the distributor or producing mill. Most manufacturers can trace a material’s production using a case, lot or heat number, which is typically noted on the package as well. Once installed, copper is easily identified by its appearance; the thickness of the copper can be measured and associated with an ounce weight. Continuous line marking or other identifiers are not normally available on architectural copper. If the installer maintained traceability records from the supplier, and the supplier has records to trace the source mill, the mill can provide test reports by tracking the production history of the original order placed with the supplying mill. Otherwise, once installed and weathered, it can be very difficult to determine the copper material manufacturer.
4.1.2 Product Selection or Material Ordering Description
Architectural copper is ordered by ounce weight or thickness and form of the product required, usually sheets or coils in varying widths. Here is a list of some standard materials used in architectural applications and in accordance with the ASTM B370 specification.
4.2 Identifying Damage
Visual indications of damage can include opened seams, laid-over standing seams, severe dents, and in some cases tearing caused by objects projected onto the roof surface.
4.2.1 Normal Shipping and Delivery Damage
Any material damage noticed at time of delivery should be reported to the delivery company. Any mill, transit, or handling damage should be documented in photos for the supplier. If possible, sign the delivery receipt, including a note of the damage. Minor dents will normally not be noticeable after the material has oxidized, and light scratches will eventually blend into the surrounding area. When exposed to water and/or chemicals during transit or once stored on site, copper will begin to weather. This should not be an issue as the copper will weather further, immediately beginning the patination process upon installation.
4.2.2 Temporary Fix
Soldering patches, some newer sealant products, and other techniques can be used for a temporary fix of a copper roof. Determining the cause of the damage will help in detailing a permanent fix. It is very important to ensure that a temporary fix will not complicate a more permanent effort at a later time. Maintenance personnel or roofing contractors will often attempt temporary fixes with sealant or membrane roofing material, which can be extremely difficult to remove or can otherwise compromise a more permanent solution.
4.2.3 Estimated Costs per Square Installed
The cost of copper changes with the commodity market fluctuations, and component price must be calculated at the time of order entry or shipment. The installation cost varies greatly depending upon the details of the project, location, scaffolding requirements, and other factors. The type of seam—whether standing or batten, or flat locked and soldered—will also determine the installed cost per square foot. Generally, the flat locked and soldered seam projects involve more labor, and are higher in cost. Although the initial cost of a copper roof or wall cladding is often higher than more common materials, life cycle costs are often much less than other materials that have a shorter expected life. The cost of the copper material for a copper roof is generally not more than $8 per square foot, while the installed cost can range from $30 to $90 per square foot. It is very difficult to provide an estimated cost, therefore, because project design, local labor rate and site specific factors overwhelm material costs.
4.2.4 Weights of Material Charts
Architectural copper is ordered by ounce weight or thickness and form of the product required, usually sheets or coils in varying widths. Here is a list of some standard materials used in architectural applications and in accordance with the ASTM B370 specification.
4.2.5 Source of Testing Lab
4.3 Determining Hail Damage
Hail does not normally severely damage a copper roof. Figure 8.3-1 illustrates an 80-year-old roof which was exposed to multiple hail events. Many small cosmetic dents are visible, along with the outline of the boards, nails, and battens that were originally installed.
However, these dents are not detrimental to the roof in this and most hail events. In severe hail cases, standing or batten seam locks can be loosened, and can often be repaired by refolding the seam. In extreme cases, panels can be separated and will need to be replaced.
While these dents may be concerning to some, copper will continue to offer a long service life and replacement should not be required. If cosmetic concerns are an issue, there are no convenient repair methods, other than replacement.
Figure 8.3-1. Example of cosmetic hail dents on a copper roof. Outlines of boards, nails, and battens can also be seen.
Figure 8.3-1. Example of cosmetic hail dents on a copper roof. Outlines of boards, nails, and battens can also be seen.
4.3.1 Repair or Replacement
Repairs or replacements for hail damage are not often needed. In the rare event there is extreme hail damage that no longer allows the roof to shed water and the seams cannot be refolded, replacements may be necessary. Refer to Section 7.2 for further details.
4.3.2 Dents
Dents are normally cosmetic in nature and will not negatively affect the roof’s longevity. On rare occasions, large solid hail may tear the copper. Inspect for penetrations; if they exist, that area should be replaced.
4.3.3 Surface Coloring Issues
Natural metals will not be uniform in color, and there are many variables that will change the surface oxidation process and ultimately vary the color of exposed copper. See paragraph 2 section 7.1. In severe cases, hail can remove some of the patina/oxidation. With time and exposure, these areas will blend back into their surroundings. No repairs are required.
4.3.4 Installation Issues
Proper handling, storage, and installation of underlayment and roof deck are critical to proper installation of the roof and minimizing hail damage.
4.3.5 Underlayment
The use of a proper underlayment and roof deck is critical to minimizing hail damage.
4.4 Determining Wind Damage
Damage from wind uplift is often found around the perimeter of a roof. Other damage may occur from the penetration of flying objects. When assessing wind damage, look for unsecured flashing, penetrations from flying debris, roof panels that are disengaged from eave flashing or, in extreme cases, entire panels or deck assemblies that may be removed.
4.4.1 Repair or Replacement
Minor wind damage can often be easily repaired by pulling up the existing panels, adding additional cleats and re-forming the standing or batten seam. Flat locked and soldered areas with wind damage will need more evaluation and possible replacement.
4.4.2 Fastening Issues
Fastener pull out for copper roofs is a concern in wind-related events. Proper copper or 300 series stainless ring shank nails, or 300 series stainless steel or brass screws are required on copper projects. Generally, these fasteners fully penetrate a ¾-in. plywood deck and provide wind uplift resistance if placed 12 in. on center or closer, as system requires with two fasteners per cleat. Panels that appear loose should be removed, and the fasteners should be inspected and tested for pull out strength.
4.5 Determining Fire Damage
Copper will begin to melt at a temperature of 1,980°F. If a copper roof has visible fire damage other than soot or a color change, concern should be focused on the substrate and determination of structural damage. It is extremely unlikely that fire will alter mechanical characteristics of architectural sheet copper without destroying other key components to the roof system. Copper will not support combustion as it does not burn.
4.5.1 Repair or Replacement
Generally, the structure and underlayment sustain more damage than the copper roof in fire-related incidents. When the underlying structure is damaged, the metal roof must be replaced. In these cases, the copper should be recycled, and the deck rebuilt to current codes.
4.6 Determining Cold Weather Damage
Although copper is not susceptible to damage from cold temperatures, components of a roof system may be. Potential concerns include ice damming at eaves and sliding ice or snow that may remove hung gutters.
4.6.1 Repair or Replacement
If ice damming has occurred, the roof should be inspected for permanent damage. Torn copper, flattened seams, and damage to fascia and gutters are not uncommon. Tears and badly bent gutters should be replaced. Seams that have been flattened can often be bent back into shape, and fascia can be re-fastened.
4.6.2 Underlayment
Ice and water shield material that is rated for high-temperature metal applications is often helpful. Proper design and ventilation is key to preventing ice formation on the roof surface.
4.6.3 Snow Retention
Generally, snow retention systems on copper roofs are only needed to protect people from falling snow. There are a number of snow retention designs and systems that can be mechanically attached or soldered to the roof to retain snow. These systems are designed for predicted snow loads in various regions; the manufacturer of the system should be consulted for load and engineering data. Galvanic compatibility is a key concern for copper roofs, as copper is often more noble than the retention system, and the components of the snow retention system can be subject to galvanic corrosion from copper and copper runoff. Painting or anodizing less noble materials is often a solution, while a 300 series stainless steel clamp or guard is fully compatible. When considering a snow retention system, ensure that the attachment method will not restrict thermal movement of the copper roof.
4.6.4 Ventilation
For the protection of copper, backside venting is not required, while other roofing panels and components may require ventilation. In all systems, ventilation and moisture control is a key design criterion. If not properly designed, this can lead to early system failures. Improper moisture control damage may be visible from the attic, but often it is not seen until a failure occurs.
4.6.5 Ice Damming
A large build-up of ice on a roof can cause water to back up the roof and find its way into the building envelope. Proper design, ventilation, snow retention systems, and insulation can minimize the occurrence of ice dams. If damage to the roof deck itself occurs, replacement of the panels involved will be required and steps to prevent repeat occurrences should be taken. While the dam is in place, various melting techniques can be employed; however, none of them are very safe and they should only be performed by an insured professional.
5. Industry Resources
5.1 Industry Associations
5.2 Technical Bulletins/Installation Guides
5.3 Resource Center
5.4 Technical Support Contacts
5.1 Industry Associations
The Copper Development Association is the industry’s trade association. Visit www.copper.org for more information.
5.2 Technical Bulletins/Installation Guides
The “Copper and Common Sense” manual provides information about size selection, seam types, corrosion concerns, expansion concerns, and other topics.
5.3 Resource Center
Copper sheets and coils can be readily found at many building products distributors throughout North America.
Installer training is often requested, and can be general or project specific. Training is available for copper roofing, flashing and trim, gutters and downspouts or wall cladding.
Training modules can include:
Soldering Techniques, Standing Seam Roofing, Batten Seam Roofing, Flat Seam Soldered Roofing, Curving Techniques, Built-in Gutters, Flashing Techniques, and Flat Seam Wall Cladding.
5.4 Technical Support Contacts
Technical assistance can be found by searching www.copper.org or www.archcopper.com.
- General Product Information
-
1. General Product Information
Copper is a roofing, flashing, gutter and wall cladding material with an extremely long history of proven performance. It combines adequate strength with superior malleability and resistance to atmospheric corrosion with a desirable self-generating patina finish. Due to the potential for long service life, copper is often selected by building owners and architects who value life cycle financial benefits over low, initial material cost.
The following sections provide generalized guidance. We encourage professionals designing, installing or inspecting copper systems to refer to industry standard guides such as Copper in Architecture – Design Handbook for more thorough information.
1.1 Packaging and Storage
1.2 Roofing Categories
1.3 Product Manufacturers
1.4 Industry-Specific Standards, Codes Requirements, and Compliance1.1 Packaging and Storage
Packaging should not trap moisture or allow moisture to penetrate the coil or sheet. Desiccants inside the package are often used when the products are to be stored for longer periods of time.
While the material is being stored and prepared for installation, it must be protected from moisture and should not be left unprotected at any stage of preassembly. Care should be taken to prevent oils, handprints, dirt and debris from contaminating the surface. Stray acids or fluxes should also be neutralized, and exposure should be limited. Proper installation techniques are required, and following the design manuals previously mentioned should provide a long-lasting roof system.
1.2 Roofing Categories
There are many proven design methods for copper roofing systems. These include, in general order of commonality:
- Standing seam.
- Batten seam.
- Flat seam (unsoldered/high slope and soldered/low slope).
- Shingles.
- Horizontal seam.
- Custom (a combination of above methods).
Although through-fastened (such as corrugated) copper roofing systems are a possibility, they are rare and typically avoided because the metal is penetrated in the process, causing a potential leak point that will only grow when the roof material is subject to thermal stress.
The design methods for copper roofing systems are listed in “Copper in Architecture – Design Handbook,” Roofing Systems.
1.2.1 Roof Pitch Limitations
A minimum slope to shed water is required for copper roofs. Minimum slope is determined by climate, roofing system, roof geometry and other factors. General slope guidelines are listed in the “Copper in Architecture – Design Handbook,” Table 8.1A, Table 8.1B, and Table 8.1C.
In some cases, copper roofs may have been installed before building codes were in place, or may be subject to variances for historical buildings. For further information, refer to the manufacturer instructions and the authority having jurisdiction.
1.2.2 Substrates and Finishes
The most common substrate for copper is wood, usually 3/4-in. plywood. Other solid substrate materials may be suitable, but industry standard recommendations or specific roof panel manufacturer installation specifications should be considered to ensure adequate fastener pull-out strength and compliance with uplift requirements.
Sheet copper is generally installed with a bare, mill-finish surface and allowed to weather naturally. Alternatives include:
- Factory, pre-patinated copper – a product with chemically induced weathering.
- Metallic coated copper – a product coated at the factory with tin or tin/zinc alloy metal.
1.3 Product Manufacturers
Copper roofing panels, flashing, gutters and wall cladding are produced by a large number of brand name manufacturers. Such products are also often locally produced by skilled sheet metal roofing contractors.
1.3.1 Current Manufacturers
1.3.2 Industry Trade Associations
The trade association for copper roofing products is Copper Development Association, Inc.
1.4 Industry-Specific Standards, Codes Requirements, and Compliance
Sheet copper for roofing systems is typically produced to meet requirements in ASTM B370: Standard Specification for Copper Sheet and Strip for Building Construction.
1.4.1 Wind
Wind uplift code requirements and enforcement vary greatly by state and region. Roofing and gutter components shall be installed to meet design load limitations as determined by the ASCE 7-10 Components and Cladding (C&C) requirements.
Copper roofing has been tested to meet the most stringent wind uplift requirements, such as the Underwriters Laboratories (UL) 580 test procedure. Generally, design of copper systems for buildings potentially subject to higher wind loads should include:
- Sturdier edge connections.
- Thicker copper.
- Narrower panel width.
- More frequent attachment of cleats/fasteners.
1.4.2 Fire
The copper portion of a roof assembly does not support combustion. The assembly fire classification shall meet the minimum code requirements as determined by the authority having jurisdiction.
- Installation Guidelines
-
2. Installation Guidelines
Refer to the manufacturer installation instructions or the Copper in Architecture – Design Handbook for details.
2.1 Roof Weights/Re-roofing
2.2 Roof Support/Sheathing Materials Options
2.3 Underlayment Options
2.4 Installation Methods
2.5 Accessory Items
2.6 Attachment of Accessories
2.7 Climatic Recommendations
2.8 Eave Treatments
2.9 Ventilation
2.10 Anti-Ponding
2.11 Ridge Treatments
2.12 Valley Flashing Treatments
2.13 Penetrations
2.14 Insulation
2.15 PV/Solar Panel Installations2.1 Roof Weights/Re-roofing
The weight of a copper roof varies depending on the style of roofing, thickness of copper, seam spacing, and attachment cleat spacing. The weight per 100 sq ft is roughly between 190 lb (narrow, batten seam, 20-oz copper panels) and 123 lb (wide, standing seam 16-oz copper panels). Copper roof physical characteristics shall meet the minimum code requirements as determined by the authority having jurisdiction.
When re-roofing a building, older roofing materials and underlayment should be removed, and the substrate should be inspected and replaced if necessary.
2.2 Roof Support/Sheathing Materials Options
The most common substrate for copper roofing is wood, usually ¾-in. plywood. Other solid substrate materials may be suitable. Refer to industry standard recommendations or the specific roof panel manufacturer installation specifications to ensure adequate fastener pull-out strength and compliance with uplift requirements.
2.3 Underlayment Options
The most common underlayment for copper roofing is 30-lb felt underlayment (specified to the latest ASTM standards covered with a red rosin paper slip sheet. The rosin paper helps prevent adhesion on the back side of the copper and allows for thermal movement. Fully adhered, ASTM D1970 underlayment products are compatible with a copper roof system, provided a high-temperature rating (refer to the manufacturer) and the use of rosin paper. Substitutes for traditional 30-lb felt have recently become popular; however, long-term temperature, ultraviolet exposure, and other tests have not yet been standardized for these products. Since this research is ongoing, refer to the manufacturer of these products to determine if the product will function for the life of a copper roof.
2.4 Installation Methods
Proper design and installation techniques will commonly allow a copper roof to function properly for over 100 years. A number of installation manuals are available, and traditional-style standing seam, batten seam, or flat locked copper roof systems are installed using these time-proven manuals. The Copper Development Association’s Copper in Architecture – Design Handbook and Copper and Common Sense are just two of the North American manuals which help determine proper seam types for various slopes, fastener spacing, expansion and contraction concerns, and many other critical details including flashing and gutter design that need to be considered.
2.4.1 Fasteners
Most fasteners in a properly installed copper roof are all concealed, except in rare conditions. These include both nails or screws which hold fixed or expansion cleats to the roof deck. Ring shank copper or 300 series alloy stainless steel nails are common. 300 series stainless steel or brass screws are also suitable. Using non-compatible fastener materials can result in galvanic corrosion to the fastener in contact with the copper. Cleat spacing should be at least 12 in. on center for standing and batten seam systems with two fasteners used per cleat. A solid, smooth, nailable substrate with proper pull-out strength is required.
2.5 Accessory Items
Snow-retention, solar, ventilation, and air-handling systems are often added onto the roof. Provisions that allow the copper to expand and contract normally must be accounted for. Contact the accessory supplier for item specifications.
2.6 Attachment of Accessories
Mechanically attached accessories are most often used on copper roofing systems. Some components can be soldered to the roof deck. Ensure that accessory items and attachment methods are galvanically compatible with copper.
2.7 Climatic Recommendations
Copper can be used in all weather conditions. However, underlayments are rated for different temperatures, which must be verified for compatibility for their intended use with copper roofs. Refer to the manufacturer of the underlayment for temperature ratings.
2.8 Eave Treatments
Eave treatments vary slightly depending on the system, but generally secure the copper roof system while allowing for thermal movement.
Two examples of eave treatments are provided in the “Copper in Architecture – Design Handbook,” 8.2D. Eave Details.
2.9 Ventilation
Backside ventilation is not required. However, proper ventilation of the building envelope may be advantageous and should be reviewed by a design professional with experience in such issues.
2.10 Anti-Ponding
A minimum slope to shed water is required for copper roofs. For flat-locked and soldered low-slope copper roof decks, the minimum slope is 0.125-in. rise per 12-ft run. Slope requirements for steep-slope copper roof systems are considerably higher, and they should never pond water. The “Copper in Architecture – Design Handbook,” Table 8.1A, Table 8.1B, and Table 8.1C., provides basic slope requirements for copper roofing systems.
2.11 Ridge Treatments
Ridge treatments are dependent upon the roof design. Details for various designs can be found in Copper in Architecture – Design Handbook and Copper and Common Sense, or in the manufacturer installation instructions.
2.11.1 Fastening
Refer to Section 2.4.1 for details.
2.11.2 Ventilation
Copper systems do not require backside ventilation to prevent corrosion. Some building owners, however, prefer to ventilate the system substrate to help prevent ice damming or to increase energy efficiency. Although other options are possible, the “Copper in Architecture-Design Handbook” presents a ventilated ridge flashing in Section 9.4B
2.12 Valley Flashing Treatments
As valley flashing collects water and geometry dictates a valley is at lower slope than adjacent roof planes, proper system design and installation becomes even more important. Examples showing the importance of valley flashing treatments are provided in the “Copper in Architecture – Design Handbook,” Section 8.2G.
2.13 Penetrations
Roofing penetrations are always an area of concern. It is very important to ensure that the penetration is watertight, while allowing thermal movement. Exact penetration design varies depending on the type of penetration. For example, a pipe boot penetration centered in a standing seam roof panel is considerably different from a large skylight that may span many seams. Examples of roofing penetrations are provided in the “Copper in Architecture – Design Handbook,” Section 9.9.
2.14 Insulation
There are no special design considerations for incorporating insulation within a copper roof system. If insulation is installed above the structural decking, ensure that the outer surface is not compressible. Cleats must be attached to or through a smooth planar surface.
2.15 PV/Solar Panel Installations
Photovoltaic or solar panel systems may be installed on copper roofing. As with all such attachments, it is very important to ensure that the mounting system does not restrict thermal movement and water and/or debris drainage and that adjacent materials are galvanically compatible.
2.15.1 Fastening
Refer to Section 2.4.1 for details.
2.15.2 Flashing
Flashing techniques for photovoltaics vary greatly depending on the system design. As with other flashing, it is very important to ensure that the flashings do not restrict thermal movement and water and/or debris drainage of the metal roof. (Refer to Section 2.12.)
- Repair & Maintenance Guidelines
-
3. Repair and Maintenance Guidelines
3.1 Natural Aging Vs. Damage
3.2 Repair or Replacement
3.3 Blending New and Old
3.4 Locating Product Sources
3.5 Disposal/Recyclability of Products
3.6 Dents and Paint Flaking
3.7 Color Fading
3.8 Fastener Failure
3.9 Maintenance/Upkeep Guidelines
3.10 Expected Product Life Cycle3.1 Natural Aging Vs. Damage
Copper roof systems often remain intact for over 80 years. Older details may have been used for these roofs and care should be taken to understand the original system. Although initial inspection can be done from ground level with binoculars, inspections are best done at roof level.
In most environments, copper will show a progression in color as it ages, ranging from bright shiny copper to black, gray, brown, and eventually green. This type of aging, known as patination, is the result of surface oxidation and the formation of copper oxide. As a copper surface matures, the oxide becomes thicker, which generally provides a natural brown or green oxide. When copper is newly installed, the surface appearance can be changed significantly with exposure to acids, fluxes, cleaning solutions, dirt and oil. Most of these changes are short-lived and the natural oxidation process will continue. Fully patinated copper will often require 25 years of exposure to the elements on a sloped surface. Patination/oxidation is aided by a sloped surface versus a vertical surface, along with higher humidity and temperature. Copper in arid regions will normally mature to a deep brown color. See the weathering color chart for a rough pictorial of typical oxidation in a northeastern U.S. climate. Time frame and ultimate color tone vary based on climate and exposure.
A proper inspection of a copper roof should include examination of the roof edges including ridge and hip areas. One area of concern is the connection of the roof to fascia or gable end. Separation in this area may indicate damage. Obvious signs like panels that have been pulled up off the roof deck can be spotted; the roof deck itself could also be damaged from debris. It is important to look at the roof deck assembly from inside the building. Proprietary copper roofing systems and panel systems may have different failure modes, and the original designing manufacturer should be consulted for specifications and inspection techniques.
It is difficult to damage a properly installed copper roof system; however, it does happen. Physical damage from maintenance, moving heavy objects, creating additional roof penetrations, dissimilar metal reactions, alterations which restrict thermal movement, and other events can cause damage and leaks. As an example, standing seams are often flattened or bent, but can often be straightened. However, the base of the seam may be subject to cracking after multiple cycles. If a puncture occurs, a small area can be deoxidized, tinned and soldered using a copper patch.
3.2 Repair or Replacement
If damage is limited to a few panels on batten and standing seam systems, it can often be repaired by removing and splicing in new panels. Taking advantage of copper’s malleability, seams can be opened relatively easily, and panels can be removed in the damaged areas, where new underlayment, roof panels, and proper fasteners can then be installed.
On soldered seam systems, do not attempt to simply resolder the seams. Old copper can be soldered; however, the material must be fully deoxidized, pre-tinned, and fluxed properly. This generally limits the ability to repair larger areas of the roof and replacement of those areas should be considered. For flat locked and soldered roof areas, replace the roof sections where a natural slope transition or expansion battens are present.
3.3 Blending New and Old
Distributors will not be able to match the color or oxidation of an existing roof with new bare and bright copper; given time, the new material will oxidize based on its environment. Some specialty products are available from manufacturers that attempt to mimic the oxidation process. Other alternatives for changing copper’s color include various chemicals which can be applied on-site to turn copper a range of colors. Because of the number of variables involved, chemically induced patinas are prone to lack of patina adhesion, excessive staining of adjacent materials, and inability to achieve reasonable color uniformity over large surface areas. These potential shortcomings should be considered when specifying such treatments. Unless the affected area is small, it is generally best to allow new material to weather naturally.
3.4 Locating Product Sources
Copper sheet and coil, along with copper-related accessories like nails, cleats and 300 series stainless steel fasteners, can be found at building product distributors that handle other roofing related products. A list of mills that produce sheet copper can be found at www.copper.org.
3.5 Disposal/Recyclability of Products
Architectural copper, generally produced from recycled product, is fully recyclable when the roof or wall system has reached its end of life. Copper is one of the most recycled architectural products and retains its value over time. Copper material should be segregated and free from other debris, and returned to a local scrap dealer for credit, which is usually determined by the COMEX or LME trading value at that time.
3.6 Dents and Paint Flaking
Generally, minor dents do not pose a problem for copper. If the surface patina is disturbed, it will re-oxidize with time and blend back into a natural appearance. While inspecting dents, look for any areas of penetration that may have been caused by a pointed or sharp object. If there are areas of penetration, replace or repair that section.
3.7 Color Fading
Natural oxidation and exposure to the elements will change the appearance of copper over time. Changes usually occur more quickly in a warm, moist environment and less quickly in arid environments. Low-slope surfaces will tend to oxidize more quickly than high slope or, slower yet, a wall cladded with copper. These color/patination changes will never be uniform like a painted material, and areas of a roof facing north versus south, areas subject to runoff, and areas with vegetation will have different appearances that are most noticeable in the early stages of oxidation. A weathering color chart shows the natural progression of color changes from bright shiny copper color (red, brown, or tan) copper to a fully patinated green.
Copper in very arid regions or areas not exposed to rainfall may only reach a deep brown/black color, perhaps with limited amounts of dark green.
3.8 Fastener Failure
Fasteners used on properly installed copper roof and wall cladding systems are concealed. Signs of fastener failure are usually panel uplift or pull off. The most common reason for failure is the use of less noble fasteners that corrode. If the roof is not severely bent or destroyed, proper copper, brass or 300 series stainless steel fasteners can be used to refasten the copper panels to the roof deck in accordance with the design manual instructions. Deck material that has been compromised by moisture or other deterioration must be replaced in most cases.
3.9 Maintenance/Upkeep Guidelines
Standard maintenance practice requires periodic inspection for loose or damaged flashings, clearing the area of standing water, and removal of debris, especially that from gutters and associated drainage components. With proper installation and design, very little additional maintenance is required for the life expectancy of a copper roof or wall cladding system.
3.9.1 Cleaning Valleys
Valley areas should be kept clear of debris, and any foreign objects should be removed.
3.9.2 Algae, Moss, Dirt, Foliage
Copper roofs prevent the formation of algae and moss. Dirt and foliage should be removed from the roof surface and gutter areas, followed by a clean water rinse. Typically, any staining on the copper roof will blend into the surrounding area over time; however, additional cleaning with non-chlorinated Tri Sodium Phosphate (TSP) may speed up the process. Caution should be taken to lightly apply the TSP so the patina is not disturbed. A low-pressure power wash could be tested in a small area prior to treating a large area. This should be followed by a clear water rinse.
3.9.3 Power Washing
A low-pressure power wash should not disturb a copper surface’s current patina and may allow for removal of some dirt and debris. If some stains remain after washing, additional cleaning with non-chlorinated Tri Sodium Phosphate (TSP) can be done, followed by a clear water rinse.
3.9.4 Walking on Product
Metal roofing should not be considered a primary roof access walkway. If it becomes necessary to walk over the top of the roofing, footwear should be clean and non-scuffing.
3.9.5 Roof Penetrations and Skylights
Proper flashing is required on copper roofs around roof penetrations and skylights. Find basic details for roof penetrations at www.copper.org, or in the manufacturer installation instructions.
3.9.6 Flashings
Flashing is one of the more critical areas of copper roof system design. Find basic details for roof penetrations at www.copper.org,, or in the manufacturer installation instructions.
3.9.7 Recoloring of Roof
Unlike many other types of metal roofing, copper is rarely painted, rather its protective finish occurs naturally through patination. Painting of copper is very dependent on ambient temperatures and surface preparation. If painting is needed or desired, consult with the paint manufacturer for the most recent product offering and directions.
Occasionally, field patination is requested. There are many chemicals that can be found online and applied to a copper surface to change its color. Most of these treatments provide varying results, depending on the surface preparation, ambient temperature and application technique. Any field applications should be fully tested, or come with references of previous successful applications prior to starting the project.
Some copper sheet and coil manufacturers can provide pre-patinated brown or green copper, under various trade names. Other reputable metal treatment and restoration firms will field patinate the copper, providing an array of appearances. Field patination, especially over large areas, rarely approaches the same appearance of a naturally weathered roof.
3.10 Expected Product Life Cycle
Properly installed copper roof and wall cladding systems can last well over 100 years, withstanding hail, wind, heat and many other environmental conditions. Copper’s corrosion resistance, formability, ease of repair, and light weight make it a reliable choice for many projects.
- Damage Issues
-
4. Damage Issues
4.1 General Information
4.2 Identifying Damage
4.3 Determining Hail Damage
4.4 Determining Wind Damage
4.5 Determining Fire Damage
4.6 Determining Cold Weather Damage4.1 General Information
4.1.1 Product Identification
The product is normally identified on the package shipped from the distributor or producing mill. Most manufacturers can trace a material’s production using a case, lot or heat number, which is typically noted on the package as well. Once installed, copper is easily identified by its appearance; the thickness of the copper can be measured and associated with an ounce weight. Continuous line marking or other identifiers are not normally available on architectural copper. If the installer maintained traceability records from the supplier, and the supplier has records to trace the source mill, the mill can provide test reports by tracking the production history of the original order placed with the supplying mill. Otherwise, once installed and weathered, it can be very difficult to determine the copper material manufacturer.
4.1.2 Product Selection or Material Ordering Description
Architectural copper is ordered by ounce weight or thickness and form of the product required, usually sheets or coils in varying widths. Here is a list of some standard materials used in architectural applications and in accordance with the ASTM B370 specification.
4.2 Identifying Damage
Visual indications of damage can include opened seams, laid-over standing seams, severe dents, and in some cases tearing caused by objects projected onto the roof surface.
4.2.1 Normal Shipping and Delivery Damage
Any material damage noticed at time of delivery should be reported to the delivery company. Any mill, transit, or handling damage should be documented in photos for the supplier. If possible, sign the delivery receipt, including a note of the damage. Minor dents will normally not be noticeable after the material has oxidized, and light scratches will eventually blend into the surrounding area. When exposed to water and/or chemicals during transit or once stored on site, copper will begin to weather. This should not be an issue as the copper will weather further, immediately beginning the patination process upon installation.
4.2.2 Temporary Fix
Soldering patches, some newer sealant products, and other techniques can be used for a temporary fix of a copper roof. Determining the cause of the damage will help in detailing a permanent fix. It is very important to ensure that a temporary fix will not complicate a more permanent effort at a later time. Maintenance personnel or roofing contractors will often attempt temporary fixes with sealant or membrane roofing material, which can be extremely difficult to remove or can otherwise compromise a more permanent solution.
4.2.3 Estimated Costs per Square Installed
The cost of copper changes with the commodity market fluctuations, and component price must be calculated at the time of order entry or shipment. The installation cost varies greatly depending upon the details of the project, location, scaffolding requirements, and other factors. The type of seam—whether standing or batten, or flat locked and soldered—will also determine the installed cost per square foot. Generally, the flat locked and soldered seam projects involve more labor, and are higher in cost. Although the initial cost of a copper roof or wall cladding is often higher than more common materials, life cycle costs are often much less than other materials that have a shorter expected life. The cost of the copper material for a copper roof is generally not more than $8 per square foot, while the installed cost can range from $30 to $90 per square foot. It is very difficult to provide an estimated cost, therefore, because project design, local labor rate and site specific factors overwhelm material costs.
4.2.4 Weights of Material Charts
Architectural copper is ordered by ounce weight or thickness and form of the product required, usually sheets or coils in varying widths. Here is a list of some standard materials used in architectural applications and in accordance with the ASTM B370 specification.
4.2.5 Source of Testing Lab
4.3 Determining Hail Damage
Hail does not normally severely damage a copper roof. Figure 8.3-1 illustrates an 80-year-old roof which was exposed to multiple hail events. Many small cosmetic dents are visible, along with the outline of the boards, nails, and battens that were originally installed.
However, these dents are not detrimental to the roof in this and most hail events. In severe hail cases, standing or batten seam locks can be loosened, and can often be repaired by refolding the seam. In extreme cases, panels can be separated and will need to be replaced.While these dents may be concerning to some, copper will continue to offer a long service life and replacement should not be required. If cosmetic concerns are an issue, there are no convenient repair methods, other than replacement.
Figure 8.3-1. Example of cosmetic hail dents on a copper roof. Outlines of boards, nails, and battens can also be seen.
Figure 8.3-1. Example of cosmetic hail dents on a copper roof. Outlines of boards, nails, and battens can also be seen.
4.3.1 Repair or Replacement
Repairs or replacements for hail damage are not often needed. In the rare event there is extreme hail damage that no longer allows the roof to shed water and the seams cannot be refolded, replacements may be necessary. Refer to Section 7.2 for further details.
4.3.2 Dents
Dents are normally cosmetic in nature and will not negatively affect the roof’s longevity. On rare occasions, large solid hail may tear the copper. Inspect for penetrations; if they exist, that area should be replaced.
4.3.3 Surface Coloring Issues
Natural metals will not be uniform in color, and there are many variables that will change the surface oxidation process and ultimately vary the color of exposed copper. See paragraph 2 section 7.1. In severe cases, hail can remove some of the patina/oxidation. With time and exposure, these areas will blend back into their surroundings. No repairs are required.
4.3.4 Installation Issues
Proper handling, storage, and installation of underlayment and roof deck are critical to proper installation of the roof and minimizing hail damage.
4.3.5 Underlayment
The use of a proper underlayment and roof deck is critical to minimizing hail damage.
4.4 Determining Wind Damage
Damage from wind uplift is often found around the perimeter of a roof. Other damage may occur from the penetration of flying objects. When assessing wind damage, look for unsecured flashing, penetrations from flying debris, roof panels that are disengaged from eave flashing or, in extreme cases, entire panels or deck assemblies that may be removed.
4.4.1 Repair or Replacement
Minor wind damage can often be easily repaired by pulling up the existing panels, adding additional cleats and re-forming the standing or batten seam. Flat locked and soldered areas with wind damage will need more evaluation and possible replacement.
4.4.2 Fastening Issues
Fastener pull out for copper roofs is a concern in wind-related events. Proper copper or 300 series stainless ring shank nails, or 300 series stainless steel or brass screws are required on copper projects. Generally, these fasteners fully penetrate a ¾-in. plywood deck and provide wind uplift resistance if placed 12 in. on center or closer, as system requires with two fasteners per cleat. Panels that appear loose should be removed, and the fasteners should be inspected and tested for pull out strength.
4.5 Determining Fire Damage
Copper will begin to melt at a temperature of 1,980°F. If a copper roof has visible fire damage other than soot or a color change, concern should be focused on the substrate and determination of structural damage. It is extremely unlikely that fire will alter mechanical characteristics of architectural sheet copper without destroying other key components to the roof system. Copper will not support combustion as it does not burn.
4.5.1 Repair or Replacement
Generally, the structure and underlayment sustain more damage than the copper roof in fire-related incidents. When the underlying structure is damaged, the metal roof must be replaced. In these cases, the copper should be recycled, and the deck rebuilt to current codes.
4.6 Determining Cold Weather Damage
Although copper is not susceptible to damage from cold temperatures, components of a roof system may be. Potential concerns include ice damming at eaves and sliding ice or snow that may remove hung gutters.
4.6.1 Repair or Replacement
If ice damming has occurred, the roof should be inspected for permanent damage. Torn copper, flattened seams, and damage to fascia and gutters are not uncommon. Tears and badly bent gutters should be replaced. Seams that have been flattened can often be bent back into shape, and fascia can be re-fastened.
4.6.2 Underlayment
Ice and water shield material that is rated for high-temperature metal applications is often helpful. Proper design and ventilation is key to preventing ice formation on the roof surface.
4.6.3 Snow Retention
Generally, snow retention systems on copper roofs are only needed to protect people from falling snow. There are a number of snow retention designs and systems that can be mechanically attached or soldered to the roof to retain snow. These systems are designed for predicted snow loads in various regions; the manufacturer of the system should be consulted for load and engineering data. Galvanic compatibility is a key concern for copper roofs, as copper is often more noble than the retention system, and the components of the snow retention system can be subject to galvanic corrosion from copper and copper runoff. Painting or anodizing less noble materials is often a solution, while a 300 series stainless steel clamp or guard is fully compatible. When considering a snow retention system, ensure that the attachment method will not restrict thermal movement of the copper roof.
4.6.4 Ventilation
For the protection of copper, backside venting is not required, while other roofing panels and components may require ventilation. In all systems, ventilation and moisture control is a key design criterion. If not properly designed, this can lead to early system failures. Improper moisture control damage may be visible from the attic, but often it is not seen until a failure occurs.
4.6.5 Ice Damming
A large build-up of ice on a roof can cause water to back up the roof and find its way into the building envelope. Proper design, ventilation, snow retention systems, and insulation can minimize the occurrence of ice dams. If damage to the roof deck itself occurs, replacement of the panels involved will be required and steps to prevent repeat occurrences should be taken. While the dam is in place, various melting techniques can be employed; however, none of them are very safe and they should only be performed by an insured professional.
- Industry Resources
-
5. Industry Resources
5.1 Industry Associations
5.2 Technical Bulletins/Installation Guides
5.3 Resource Center
5.4 Technical Support Contacts5.1 Industry Associations
The Copper Development Association is the industry’s trade association. Visit www.copper.org for more information.
5.2 Technical Bulletins/Installation Guides
The “Copper and Common Sense” manual provides information about size selection, seam types, corrosion concerns, expansion concerns, and other topics.
5.3 Resource Center
Copper sheets and coils can be readily found at many building products distributors throughout North America.
Installer training is often requested, and can be general or project specific. Training is available for copper roofing, flashing and trim, gutters and downspouts or wall cladding.
Training modules can include:
Soldering Techniques, Standing Seam Roofing, Batten Seam Roofing, Flat Seam Soldered Roofing, Curving Techniques, Built-in Gutters, Flashing Techniques, and Flat Seam Wall Cladding.5.4 Technical Support Contacts
Technical assistance can be found by searching www.copper.org or www.archcopper.com.
