Warm Flat Roof Insulation Thickness

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 roof insulation thickness.

Our u value calculator is free and simple to use for calculating u values specific to your roof construction design. 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. There are two types of 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. 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. The typical u value of an existing uninsulated flat roof is 1 5w m2k. The roof insulation thickness will vary dependent on the required u value.

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. It should be of the maximum available thickness. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity.

U value of a flat roof. Insulating a flat roof with recticel powerdeck u recticel s powerdeck u offers 0 024 u value for thicknesses 120mm or more so it s a great thermal insulator as well as a strong and stable board for structural integrity. A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value. Inverted roofs are a type of warm flat roof where the insulation is above the waterproofing layer.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. To comply with part l of the building regulations 2010 all roofs to rooms except those in unheated buildings should be thermally insulated to a maximum u value of of 0 18 w m k. The target should be to achieve a u value of 0 25w m2k or better. Kingspan and recticel are the two of the most well known flat roof insulation brands and they re firm favourites of insulation superstore customers.