Single Ply Flat Roof Installation









The Sarnafil single ply membrane is a strong flexible PVC material that can either be mechanically fixed or adhered to an underlying surface.  The membrane is installed without naked flames, hot bitumen, multiple layers or resins. It ‘s simply secured to the roof using the most appropriate method (including metal look alike standing seams or batten rolls if you wish) specified by our Roof Assured registered installer. The roof consists a structural deck, a loose laid vapour control layer, insulation and finally either the mechanically fastened or adhered single-ply membrane.

NEW – Self adhered membraneInstallation times can be cut by up to 50 per cent, with no need for the use of adhesives on site, courtesy of the new Sarnafil self adhered membrane. This multi layer synthetic roofing membrane is a premium quality PVC material with an inlay of glass, non-woven for dimensional stability, and with a self adhesive polyester fleece backing. The membrane contains ultraviolet light stabilisers which assist weathering in direct exposure and is flame retardant.

Steel edge trims can be added to provide strong weather resistant roof edges. There’s also the option of decorative profiles that simulate a leaf “batten roll” or a zinc or copper “standing seam” effect, to maintain the traditional look of a heritage property. This metal effect is particularly liked by self builders and renovators who are looking for the ‘natural architectural’ appeal of a metal roof without the cost or maintenance.

Flat Roof Insulation

Insulating a flat roof can deliver real benefits; a warm comfortable room, lower energy bills and improved energy ratings. Building regulations can also mean insulation is compulsory. Specifying Sarna Therm insulation, a Sarnafil branded polyisocyanurate foam insulation board, ensures that the insulation is also covered under the Sarnafil product guarantee.

 Cold Deck

This is a common roof construction but can be the least thermally efficient an done of the most problematic. This roof design can be prone to the manifestation of condensation within the roof void. From the room ceiling up the build is as follows: the ceiling is attached to the roof joists that support the roof construction. A polyethylene vapour barrier is laid into the roof void and mineral insulation is loose laid between the rafters. The roof deck is then fixed to the rafters and the water proof membrane is then installed. In most cases this construction will have to be ventilated to avoid condensation.

Warm deck

This is the most modern method of construction and is recommended where possible (although not all situations are able to accommodate this design).


From the room ceiling up the construction is as follows: The roof joists support the roof construction the internal ceiling is attached to these. On top of the joists the roof deck is fixed. A vapour barrier is laid on to the deck and the appropriate thickness of insulation is fixed to the roof deck. The waterproof roof cover is then installed.

This method of insulating the roof alleviates the condensation forming in the roof void (subject to the correct design & condensation risk analysis) and complies with the current building regulations.










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