The typical roof system includes a roof covering, roof sheathing and supporting roof frame. Nonstructural lightweight coverings, such as timber or asphalt shingles usually behave well during an earthquake. Other types of roof coverings, which are heavy, tend to not stand up so well and are also susceptible to sliding or falling off the roof during an earthquake.
What lies under the roof covering is what gives the roof its strength. Plywood substrates give strength to the roof regardless of the roof style. Roofs fully covered with structural grade plywood tend to provide the greatest stability to the overall structure.
Re-roofing with shingle products is made easy by utilising the existing roof purlins or battens or by fixing the plywood directly to the trusses.
Tim Newsham from Marlborough Shingle & Shake Roofing, Blenheim has just completed a re-roof on the St Andrews Church Building in Blenheim using South Pacific Shingles Owens Corning Duration Premium Asphalt Shingles in the Estate Grey colour.
St. Andrews Presbyterian Church, Blenheim was designed by Sir Michael Fowler and built about 37 years ago by local firm T H Barnes. Original three tab shingles had stood up well for what were probably 20 year shingles.
Tim re-roofed two faces eight years ago on the fifty degree pitch and went over old shingles except on southerly face where the tabs were cut off. Total reroof including skips and scaffolding was under $40,000.
For specifications and technical drawings please view the online resource.