Thickness Of Insulation For Warm Flat Roof

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.

Thickness of insulation for warm flat roof.

One of the main benefits you will receive from installing a warm flat roof is condensation will not become an issue because of the positioning of the insulation. Inverted roofs are a type of warm flat roof where the insulation is above the waterproofing layer. Warm flat roofs do not need to be ventilated as the insulation is. Insulation in a warm roof.

It should be of the maximum available thickness. Thickness varies according to the manufacturer s specifications. The insulation for a warm roof will usually be boards of extruded polystyrene or rigid compressed boards of glass fibre or rock fibre. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same.

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

This is placed over the roof joists and a board normally external ply is laid on top. Ventilation is required for these roofs. 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. Flat roof insulation thickness.

At least 100mm of rigid board insulation must be positioned on top of the vapour control layer the vapour control layer stops any moisture within the building. 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. 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. 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.

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