There are two basic categories of roof design.
Warm deck roof insulation thickness.
The vapour control layer is above the decking but below the insulation.
Set the quinn therm qrfr ply insulation boards onto a wide 30mm bead of vapour resistant sealant applied to the upper surface of all the joists and cross noggins.
Add to this the firring pieces for slope say 75 max.
The insulation is immediately below the waterproofing layer.
Cold deck roof a cold deck roof is where the insulation is placed between the joists rafters or in.
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 can be adhered mechanically fixed or loose laid.
No ventilation is required for these types of roofs.
The waterproof layer is above the insulation and a vapour control layer is placed below the insulation.
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.
They lose loads of heat and are prone to leaking causing the materials to deteriorate.
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.
How to install insulation in a flat roof with timber deck insulated above the joists.
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.
Ventilation is required for these roofs.
Warm deck flat roof insulation is now the standard way to insulate a flat roof click to enlarge flat roofs for example on extensions bathrooms and dormer windows are not the best of ideas.
18 thickness of deck.
Min 125 thickness of insulation board then finish on top.
A flat roof where the insulation sits below the waterproof membrane and above the structural deck is a warm roof deck.
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.
Warm deck roof a warm deck roof is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation.
