Copper and its commonly used family of alloys of brass and bronze have been utilized for hundreds of years. They are one of man's oldest family of metals. Over this time period, many questions and much research has gone into this metal. CDA has collected some of these questions in an easy and clear format to allow quick response to the most commonly asked questions.
Should you have a question that is not included, please contact our Project Managers & Architectural Applications Specialists.
Where can I get help on copper design techniques?
CDA's Project Managers & Architectural Applications Specialists can assist you in a variety of ways from in-house seminars to project design assistance to document and specifications review to contractor recommendation. Project managers are currently available to assist architects, specifiers, contractors and owners involved in any type of copper project. See Project Managers & Architectural Applications Specialists for more information.
What is the availability of copper specifications?
CDA has published five architectural copper specification sections in the AIA Masterspec format. Please refer to the Copper in Architecture Specifications.
Can the naturally occurring green patina of copper be accelerated by artificial chemicals?
Due to the precise temperature, humidity and chemical requirements, it is generally not recommended that copper be artificially patinated in the field. However, there are field applied prepatination systems that, with proper training, have proven successful. Currently there are U.S. sheet copper fabricators who provide factory-and field-applied prepatination systems under controlled environments. The patina is produced using patented chemical processes result in true patina chemical conversion coatings that carry extensive warranties. The companies providing these finishes are listed in Sheet Copper Manufacturers.
Do you have information on distributor location and availability of products?
Copper products are sold by the manufacturers through a network of distributors. For a list of distributors in your region please call the manufacturers as listed in the list - Sheet Copper Manufacturers.
Who are the contractors in my area?
CDA has compiled a list of the best architectural copper contractors in the US and Canada into an interactive database. To retrieve a list of contractors for your particular location please refer to the Installation Contractors Database.
Where can I get copper or copper alloy samples?
Different alloys are fabricated by different manufacturers. If the alloy number is known then a search through CDA's literature is recommended. If the alloy number is not known, contact CDA. Alloy Sources and Specifications Index.
Are cedar shingles and copper flashing compatible?
Shingles, if installed in direct contact with metal flashing, will wick water through capillary action under the leading shingle edge. The water will tend to remain in contact with the flashing and build up in acidity. This acid-laden water will corrode flashing in a linear fashion leading to "line corrosion" or pinholes in the flashing. The correct detail is to raise the leading shingle edge on a cant thus breaking the bond between shingle and flashing. Extensive details are included in CDA's Copper in Architecture Design Handbook.
How can the staining of materials by copper be prevented?
The natural weathering of copper results in the formation of copper salts at the surface of a copper sheet. These salts are then mixed with rain water and if allowed to run on to other materials will cause the characteristic green stains. To prevent such stains, the use of overhangs, sloping of copper surfaces away from other materials, gutters, and drip edges are all recommended. The use of a clear, silicon-based coating on cementitious surfaces is also useful to help protect the surface during the initial and most aggressive weathering of the copper.
Have copper roof systems undergone any U.S.-recognized test procedures?
Testing of a standing seam and flat locked and soldered seam system have been completed. Both systems have received UL-90 designation and can be referenced in the UL Building Materials Manual under Construction #496 and #550 respectively. For information on additional ongoing tests, please contact your local Regional Manager.
What is galvanic corrosion and how can it be prevented?
Metals are rated according to their nobility ratings. When dissimilar metals are in contact with each other in the presence of oxygen and moisture, the more noble metal will corrode the less noble. Copper is one of the most noble of metals and must be separated from other less noble metals. Contact between dissimilar metals should always be avoided. If contact cannot be avoided, the adjacent surfaces should be painted with bituminous or zinc chromate primers or paints. Taping or gasketing with non-absorptive materials is also effective.
Care should be taken to prevent the wash from copper surfaces onto adjacent, exposed less noble metal surfaces, since the traces of copper salts carried in the wash can accelerate the corrosion of less noble metals.
Are sealants required with copper systems?
Most copper installations depend on self-flashed details requiring no sealants. Under some conditions, such as low roof slope situations, the use of sealants is recommended as a secondary waterproofing material. However it should be noted that copper will outlast most sealants and that in any details using sealants a regular maintenance and inspection program will become necessary. In general, butyl, polysulfide and polyurethane sealants are reasonably compatible with copper. Acrylic, neoprene and nitrile-based sealants actively corrode copper. Silicone sealants have a variety of success with copper, but their suitability should be verified with the manufacturer.
What is the role of solder in a copper system?
In roof and wall systems where water-tight seams are required, soldering is specified. A soldered seam will join two pieces of copper into a cohesive, watertight unit that will expand and contract as one piece. Well soldered seams are, in many cases, stronger than the original base material and will provide many years of satisfactory service.
What are the typical sizes for architectural copper products?
Copper products are available in three distinct forms: strip, sheet, coil, sized as follows:
- Strip Copper:
Weight in oz./sf: 16, 20, 24, 32, 48.
Width in inches: 10, 12, 14, 15, 16, 18, 20, 24.
Length in inches: 96, 120, coil.
- Sheet Copper:
Weight in oz./sf.: 12, 16, 20, 24, 32, 48.
Width in inches: 30, 36.
Length in inches: 96, 120, coil.
It should be noted that US copper is presently available in maximum widths of 36".
What are the environmental concerns regarding water run-off from copper roofs?
CDA, along with its sister organization ICA, is involved in extensive environmental testing and analysis of water runoff issues in various international locations. To-date, this information has been compiled in a summary report entitled Copper Roofs and Water Runoff.
Are there any copper shingle manufacturers?
Within the USA an Canada, there are at least 11 copper shingles manufacturers. These systems are manufactured from solid copper products with specific installation instructions and warranty systems. For additional information, see Copper Roofing Shingles Manufacturers.
Why does copper change color?
The natural weathering of copper is a direct consequence of the corrosive attack of airborne sulfur compounds. This leads to a gradual change in the surface color until equilibrium is reached and the change is stabilized. The final color is different and depends on the location and local weather. Salt, moisture, sunlight and orientation can effect the final color. In general, copper changes in hue from a natural salmon through a progression of russet browns, grays and finally to a blue-green or gray-green patina.
What are the advantages of using copper flashing?
Copper flashing offers beauty, low maintenance and a long service life. Unlike most other flashing materials, copper doesn't need to be replaced when the roof is replaced.
What is the service life of copper flashing?
Copper flashing, when correctly installed, can outlast the life of a house and far outlast the life of most roof systems. A service life of over 80 years has been common for copper flashing.
Is copper flashing expensive?
Copper is about equal in cost to galvanized steel and is initially somewhat more expensive than other shorter-lived materials. Copper flashing is well matched to high-performance roof systems and will not need replacement for the life of the roof. On a life-cycle-cost basis, copper flashing is the best choice.
What is the purpose of the lead in lead-coated copper?
Lead-coated copper is the copper industry's response for a strong, lightweight, durable, easy-to-install gray metal finish on a copper substrate. The material has been available since the early 1900s.
Lead-coated copper does not extend the life of a copper roof. Its purpose is to provide an alternative color to architectural copper applications. In addition, lead-coated copper runoff fulfills the objective of providing a metal whose runoff staining is compatible with light-colored materials such as masonry, marble limestone, stucco and light painted woodwork. The stains produced range from light to dark gray in color and resemble the natural atmospheric weathering of masonry or paint. In instances where the lead coating is porous, under exterior conditions, incomplete or pitted, rapid pitting corrosion of the underlying copper can occur due to galvanic action.