With a big increase in the use of western cedar shingles for roofing projects, Professional Builder has asked Marley Eternit to create an overview for installing them.
Things you need to know before you start
• Choose Blue Label shingles, as Red, Black and Green Label shingles are not suitable for roofing or cladding in the UK.
• Look for the Certi-Grade quality assurance label.
• Use online calculators to estimate the amount of bundles required. By way of example, one bundle will cover 2.28m2 for roofs between 22 and 89 degrees where the maximum gauge is 125mm.
• JB ShingleFix can reduce installation costs by up to 65 per cent for low-pitched roofs (95mm gauge) and up to 50 per cent for standard roofs (125mm gauge).
• JB Shingles are treated with a clear preservative treatment, MicroPro, to retain the natural look of cedar
The shingles should be fixed at the appropriate gauge directly onto roofing battens. A double course of shingles should be used as a starter course at the eave.
The shingles should project at least 38mm beyond the eave protection or if a gutter is used at least to the centre line of the gutter. They should extend 38mm over the verge or gable moulding/bargeboard.
The shingles shall be spaced 6mm apart and be nailed or stapled twice; the nails/staples should be fixed 19mm in from the edge and 38mm above the butt of the course above.
Joints in any one course should have a side lap of no less than 38mm from the joint in adjacent courses and in any three courses, no two joints should align.
Battens should be strong and stiff enough to withstand the proposed loading and provide adequate fixing and alignment.
• Spend some time selecting the best face of the shingles and then nail a double starter course, separating shingles approximately 6mm apart.
• Use timber roofing battens such as JB Red and counter battens with a membrane to allow adequate air flow if necessary.
• Use two 31mm x 1.8mm silicon bronze nails per shingle.
• Use four 45mm x 2.65mm silicon bronze nails for hip and ridge capping.
• For speed and to simplify installation, use preformed hips and ridges. When installing, start at each edge and work towards the middle.
For more information visit www.marleyeternit.co.uk