Warm Deck Flat Roof Insulation Thickness

A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck.

Warm deck flat roof insulation thickness.

The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof. The typical u value of an existing uninsulated flat roof is 1 5w m2k. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. The target should be to achieve a u value of 0 25w m2k or better.

Others would treat even steeper pitches as flat roofs. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. To calculate u values and insulation thickness specific to your project use our free online u value calculator. Warm flat roofs do not need to be ventilated as the insulation is.

The required thickness of quinn therm flat roof insulation will depend on the desired u values. It should be of the maximum available thickness.