Warm Flat Roof Insulation Thickness

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay.

Warm flat roof insulation thickness. The chosen insulation laid on top of this should be able to take the weight of anything put above it on the roof without compression or protected from compression by further sheeting. These are can be supplied with rebated edges which interlock reducing the risk of uplift. However if we do not include removal of old roofing you are looking at about 7 50 to 9 00 per foot of roofing plus about 2 50 to 3 00 per foot of 5 thick insulation say about 10 12 per square foot. Warm deck the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck. Insulation in a warm roof. It should be of the maximum available thickness.

A cold roof has the insulation placed below the structural deck which thus remains cold. 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. Ventilation is required for these roofs. The typical u value of an existing uninsulated flat roof is 1 5w m2k.

This means that the insulation should be highly resistant to water absorption for example an extruded polystyrene based product which will not be affected by water or repeated freeze thaw cycles. There are two basic categories of roof design. Cold roofs and warm roofs. This is placed over the roof joists and a board normally external ply is laid on top.

Inverted roofs are a type of warm flat roof where the insulation is above the waterproofing layer. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. The waterproof layer is above the insulation and a vapour control layer is placed below the insulation. 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.

The insulation material for a warm flat roof should. Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation. Warm flat roofs do not need to be ventilated as the insulation is. A warm roof has the insulation above the structural deck which is thus kept warm.

Flat roof insulation thickness. There are two types of flat roof.