Warm Deck Flat Roof Insulation Thickness

U value of a flat roof.

Warm deck flat roof insulation thickness.

When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. 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. Reason i ask is because i m trying to work out whether my upstairs toilet waste pipe will be high enough to divert on top of the flat roof to the side of the house.

Install epdm rubber roof as per installation instructions. A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck. The target should be to achieve a u value of 0 25w m2k or better. To do this you will need to.

Flat roof u value 0 18 w m2k 2 warm deck flat roof the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications. Warm flat roofs do not need to be ventilated as the insulation is. To calculate u values and insulation thickness specific to your project use our free online u value calculator. Although i m sure this can differ considerably depending on insulation etc can anyone tell me what the approximate thickness of a warm deck flat roof will be including joists.

Overboard the insulation with a 9mm 11mm ply or osb3 board. What thickness of roof insulation to use in concrete deck warm roof construction the thickness of insulation required will be dependent on the u values you wish to achieve. Others would treat even steeper pitches as flat roofs. The required thickness of quinn therm flat roof insulation will depend on the desired u values.

The below u value table shows the required insulation thickness based on the typical warm flat roof construction outlined. In this warm deck construction the number and type of mechanical fixings can change the thickness of insulation required. Screw the 9mm board and insulation down into the existing roof joists. A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.

Cold flat roofs are typically avoided as you d need to install ventilation which can prove problematic for many reasons relating to space labour costs etc.