Copper is very well suited for use as a roofing material. It has natural qualities which prevent corrosion and deterioration and is generally easy to work in thin sheets ranging in thickness from 0.5 – 1.5mm. When exposed to the elements copper develops a natural patina on its surface which acts as a barrier against corrosion and protects the underlying metal. This patina is also what gives copper roofing its characteristic green colour which develops over a number of years after initial installation.
Installation & Common Issues
A great example of traditional copper roofing techniques, the roof at Gort Glas is constructed of vertically laid sheets of copper approx. 700mm x 1800mm including joints and folded seams. A 60mm copper strip is installed on the ridges of the roof. The ends of the vertical standing seams are turned down and folded into welts at the ridge and gutter pipe level. The copper sheets are installed using the “Long Strip” method and joined along the vertical edges using the “Standing Joint” method without the use of solder. The horizontal joints where the sheets meet are joined with a single cross welt joint turned up in the centre to aid water runoff. This method of joining the ends of the long sheets is a very unique and seemingly effective technique. Typical issues arising with copper roofing include:
- Localised cracking of standing seams and cross-welts usually resulting from “work-hardening” of the copper during installation
- Corrosion and staining when in contact with other metals and moisture
- Pitting - small areas of the copper sheet may start to erode due to impurities in the material
- Wind damage – due to the large size of the sheets they are susceptible to a lot of movement in high winds which may lead to cracking or lifting of the seams
- Failure of soldered seams and joints
The copper roofing at Gort Glas is in very good condition for its age and is a very good example of the quality of craftsmanship in traditional copper roofing techniques of Ireland in the 1960’s.