Flat Roof Build - Ups

A flat roof is a type of roof design that has a low pitch or no pitch at all, resulting in a horizontal or nearly horizontal surface. Flat roofs usually have a slight slope to allow for water runoff. They are commonly used on:

• Commercial buildings

• Residential structures

• Modern architectural designs

EPDM rubber membranes are suitable for use in most flat roof systems. EPDM is durable, waterproof and low maintenance, making it a great choice for this type of roofing system. The finished EPDM flat roof should have a fall of at least 1 in 80 (1.25%) as recommended by Single Ply Roofing Association (SPRA) to ensure water runoff. There are two main roof build-ups for a flat roof, a warm roof and a cold roof.

Warm Roof

A warm deck roof is the more modern roof build-up and preferable where possible. It is called a warm deck roof because the insulation is above the joists and main deck, meaning the entire roof structure is insulated (and warm). The benefit of this is that the chance of condensation within the roof structure is reduced. Unlike cold deck roofs, there is also no need to vent the roof void. If you are installing a warm roof over an existing roof, it is possible to leave the original roof covering in place to act as the vapour barrier as long as it is in good condition. Here are some benefits of a warm roof:

• Heat retention

• Reduced condensation risk

• Energy efficiency

• Enhanced comfort

Cold Roof

Cold deck roofs are the most common and traditional method of roof build-up and can be retrofitted where it is not possible to build a warm deck. Cold decks are so-called because the insulation is placed directly above the ceiling boards, and a cavity left between this and the roof deck. The air in this area is essentially outside and cold, so must be well ventilated to avoid condensation occurring.

Flat roofs offer many advantages. Compared to sloped roofs, they require less materials and labour making them largely more cost-effective to install. Many modern architectural designs feature flat roofs as they provide a more sleek and minimalist appearance, complementing the overall contemporary aesthetic. Flat roofs can also be used to maximise space. For example, additional storage or even to create a rooftop garden!

Discover our wide range of EPDM supplies here. From handy walkway pads to our all-in-one roof kit, we’ve got everything you need to complete your flat roof project!