Warm Deck Flat Roof Insulation Thickness

The target should be to achieve a u value of 0 25w m2k or better.

Warm deck flat roof insulation thickness. Saint gobain insulation uk manufacture and supply glass mineral wool slabs and rolls along with rigid polyisocyanurate pir boards that can be considered suitable for a wide range of applications across flat roofs whether you re looking to insulate at joist level or above the roof deck in your flat roof construction. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. Thickness varies according to the manufacturer s specifications. 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.

Add to this the firring pieces for slope say 75 max. It should be of the maximum available thickness. The typical u value of an existing uninsulated flat roof is 1 5w m2k. To construct a mechanically fixed warm deck using epdm you will require.

18 thickness of deck. Roof deck minimum 18mm ply or osb3 oriented strand board deck new vapour barrier or leave the existing felt membrane in situ if this has not suffered water damage kingspan tr26 foil backed insulation or similar 9mm 11mm ply or osb3 board. The joist size depends on your span but assuming you are going out say 3m or so your joists would be about 150 deep.