A warm flat roof is a construction which has an insulation layer above the rafters which is based immediately below its weatherproof membrane. This type of roofing has many benefits over a traditional ‘cold roof’ with it being a breathable roof construction which allows moisture to escape and prevents damp and any decay problems. A warm roof allows heat to be conserved inside a property without needing a ventilation system. Jacob James Roofing provide warm roofs that are thermally efficient and cost-effective and are now commonly accepted as the best roofing structure for properties across the UK.

Understanding Structural Loads for Pitched Warm Roofs

Structural loads on a pitched warm roof need to be considered differently than those on a traditional cold roof. For cold roofs, the weight is supported directly by the rafter. Whereas for warm roofs, the weight is taken up by counter battens that are laid on top of the insulation. The counter batten forms part of a composite rafter above the insulation and effectively becomes a structural member that tile batten can be fixed, plus at the same time holds down the insulation against wind suction.

What is a Sliding Load?

Insulation thickness will increase over time meaning sliding or bending loads are imposed on the counter batten. The laid weight of the roof covering and the roof pitch can affect the sliding load. The heavier the tile and the steeper the roof, the greater the load becomes. A consequence of the sliding load based under the weight of the roof covering the insulation can compress which lowers its thermal performance.

Wind Suction

The counter batten needs to be thick enough to grip the roof covering the fixing method which enables it to resist the wind uplift. It must not buckle under the sliding load between fixings plus it must be wide enough to meet the manufacturers requirements for clamping the insulation. Wind suction is affected by the anticipated wind speed, the height of the building, the site exposure and the local topography.

Talk to the Flat Roofing Specialists

If you are looking for trusted installers of warm flat roofs, get in touch with Jacob James Roofing for a no-obligation quote.