Flat Roof Dormer Insulation

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.

Flat roof dormer insulation.

The traditional cold deck flat roof system is to install the insulation between and under the joists with ventilation below the timber deck. They lose loads of heat and are prone to leaking causing the materials to deteriorate. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. 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 after taking some photos on the flat roof it is apparent there is already some kind of insulation present. Cold roof a very bad idea. We also have insulation boards suitable for more specialist roof applications for example inverted roof insulation and balcony insulation. When using the rigid form of insulation it is possible to place counter battens underneath the battens used for the tiles or slates.

We have a wide range of roof insulation products including flat roof insulation tapered insulation and pitched roof loft insulation. Tlx silver is a vapour barrier and this structure gives no risk of surface or interstitial condensation. The rigid insulation method requires the utilisation of 150mm thick insulation in between the rafters along with a 50mm air gap in order to avert cold bridging. Tlx silver can be used to reduce the thickness of additional insulation required between the joists to help ensure a ventilated gap is maintained between the insulation and the deck.

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 produce a hot roof rigid insulation is fitted outside above the weatherproofing. Now to the actual question how can you insulate a dormer roof. Insulating a dormer roof to insulate a new dormer the same three methods can be used however there are changes to the construction method that can be used.

This is then covered with a further weatherproofing layer. The photos suggest 25mm of mineral fibre on the underside of the roof.