Are single ply flat roof membranes suitable for use on pitched roofs?

Posted on January 10, 2022 by IKO-Team

A single ply membrane can be used to provide the waterproofing finish for a pitched roof, and there is no limit on the slope of the roof for which it can be used. BS 6229:2018, the code of practice for flat roofs with continuously supported flexible waterproof coverings, even advises that many of its recommendations can also be applied to pitched roofs.

A pitched roof is defined as being a roof with a pitch greater than 10 degrees. While a roof with a pitch of, say, 12 or 15 degrees would be considered a pitched roof by this definition, it would inevitably have many of the hallmarks of a flat roof, so it is clear to see why a single ply membrane flat roof system would remain suitable for such a design.

Why are single ply flat roof systems less commonly used on steeper pitched roofs?

Slate, and clay and concrete tiles, are part of the UK’s building heritage, and remain the ‘go to’ solution for many pitched roof projects. Generally speaking, the lowest pitch for which roof tile and slate solutions are available is around 15 to 22.5 degrees.

Consider also that pitched roofs are rarely insulated in the same way as a warm flat roof, with the insulation installed over the roof structure and the waterproofing directly over the thermal insulation. However, if factored into the design from an early stage, there is no reason why a single ply flat roof system cannot also be used on steeper pitched roofs too.

IKO Polymeric’s technical support team are on hand to offer more advice about designing for the use of single ply membranes on pitched roofs.