8. Roofing Systems


Copper offers a character and durability that no other metal roof can match. Its appearance can complement any style of building, from the traditional to the modern. Its warmth and beauty make it a preferred material for many architects.

The use of copper is based upon traditional practices proven over many years. There are numerous examples of copper roofs which have been in place one or more centuries. Copper's resistance to the elements ranks among the highest of modern roofing materials.

When properly designed and installed, a copper roof provides an economical, long-term roofing solution. Its low life cycle costs are attributable to the low maintenance, long life and salvage value of copper. Unlike many other metal roofing materials, copper requires no painting or finishing.

Through its natural weathering process, the warm bronze tones can be expected to lead to the elegant green patina finish. There are also a number of methods available to retard or accelerate the weathering process. These methods are currently under study, with results to be issued in subsequent updates. See Finishes Section for current information, or contact CDA.

The ductility and malleability of copper make it an easy material to form over irregular roof structures. Domes and other curved roof shapes are readily handled with copper.

In recent years, new tools and installation methods have been introduced that aid in the quick, proper, and economical installation of copper roofs.

Typical Requirements

  • Decking Requirements:
    Different roofing systems have different fastening requirements. In general, they can be divided into two categories: those systems that use cleats secured to battens and those whose cleats are fastened directly to the roof deck.

    Batten systems may be applied over any type of decking. On concrete, gypsum, or steel decks, the wood battens may be secured by thru-bolts, expansion inserts or similar anchoring devices.

    For systems that use cleats secured directly to the deck, it is imperative that the holding power of the deck is adequate to sustain design wind conditions. If the surface to receive the roofing is other than wood or a nailable deck, nailing strips or inserts must be provided to secure the cleats. Nailers should, in general, be installed transverse (perpendicular) to the seams rather than parallel to them since variations in the widths of finished pans make it impossible to assure proper alignment of seams over parallel nailers for an entire roof.
  • Materials:
    Copper roofing is typically constructed using 16 oz. or 20 oz. cold rolled copper sheets. Sheets can be either preformed or formed in the field into pans. Pans up to 10 feet long are considered short pans. Roofs using pans longer than 10 feet should be designed to accommodate additional movement at the ends of the pans. For additional information, see Roofing Systems–Long Pan.

    The copper pans rest on 4 lb., minimum, rosin-sized smooth building paper. The underlayment is typically 30 lb., minimum, saturated roofing felts. Other materials may be substituted in specific applications. See the specifications and manufacturers' recommendations.
  • Surface Preparation:
    The surface preparation for copper roofing systems is similar. The deck should be thoroughly dry, smooth, and free from projecting screws, nail heads or other imperfections. The entire surface should be covered with an approved underlayment secured with copper nails and washers. The underlayment, which is often saturated roofing felt, acts as a cushion, as well as providing temporary weather protection for the roof deck.

    A sheet of building paper must be applied over the felt. Because copper has a tendency to conduct heat, elevated temperatures can cause asphalt in the underlayment to bond the copper to the roof deck. This inhibits the movement of the copper roof and can result in premature fatigue. The building paper acts as a slip sheet to prevent such bonding.
  • Equipment:
    A variety of power pan formers and power seamers are available to assist in the construction of copper roofs. Power pan formers can take flat or coiled, sheet or strip copper and produce roofing pans on site. They result in high quality, uniform pans whose length is limited only by the contractor's ability to transport and handle the material (pan lengths should not exceed the recommendations in the Roofing Systems–Long Pan). Pan formers typically have the ability to produce pans of varying width with 1" high standing seams.

    Power seamers are used to produce finished standing or batten seams. The seamers are engaged onto an unfinished seam and propel themselves under electrical power the length of the seam. They can form seams of virtually any length.