Warm Roof Construction Insulation Thickness

The insulation material for a warm flat roof should.

Warm roof construction insulation thickness.

A major factor influencing the design of pitched roofs with insulation at ceiling level is the type of roof tile underlay chosen. 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. This is placed over the roof joists and an board normally external ply is laid on top. 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. It is possible to achieve very high levels of insulation in pitched roofs where the insulation is positioned at ceiling level because the insulation thickness is largely unrestricted by construction considerations. Our u value calculator is free and simple to use for calculating u values specific to your roof construction design. The roof insulation thickness will vary dependent on the required u value.

Tony1851 30 aug 2012. The thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. If you are draining the whole roof to one corner you can try putting the firring pieces diagonally 45 deg across the roof joists. Insulation in a warm roof.

An inverted roof construction sees the principal thermal insulation layer located above the roof structure and also above the waterproofing this method results in the waterproofing the structural deck and the support structure all being at a temperature similar to that of the interior of the building. 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. They increase in depth by a small amount each one say 1 8. Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam.

Warm flat roofs do not need to be ventilated as the insulation is. A warm flat roof or a built up roof bur is one where all the insulation is above the joists deck making them part of the warm fabric of the building. The insulation for a warm roof will usually be boards of extruded polystyrene or rigid compressed boards of glass fibre or rock fibre. The insulation is immediately below the waterproofing layer.

The sheets are laid at 90deg to the firrings. The vapour control layer is above the decking but below the insulation. A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck. These are can be supplied with rebated edges which interlock reducing the risk of uplift.