Warm Flat Roof Insulation Thickness

Ventilation is required for these roofs.

Warm flat roof insulation thickness.

Cold roofs and warm roofs. 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. 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.

Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. The insulation for a warm roof will usually be boards of extruded polystyrene or rigid compressed boards of glass fibre or rock fibre. 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. Cold deck this is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. Inverted roofs are a type of warm flat roof where the insulation is above the waterproofing layer. In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. Flat roof insulation thickness.

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. A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck. Thickness varies according to the manufacturer s specifications. 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.

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 types of flat roof. The typical u value of an existing uninsulated flat roof is 1 5w m2k. Insulation in a warm roof.

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. These are can be supplied with rebated edges which interlock reducing the risk of uplift.