Insulating A Flat Roof From Outside

Rigid foam panels are available in thickness.

Insulating a flat roof from outside.

Materials used to make insulation in these three types include mineral wool fiberglass cellulose fiber vermiculite styrofoam polystyrene and polyurethane. Many properties use this option as there are no additional costs for scaffolding or organising how to gain safe access to the roof exterior. While insulation for a flat roof is expensive and can account for as much as 25 of the total installation cost there are a number of important benefits to having it in place. A roof over a vented unconditioned attic does not need to include any insulation.

The correct method for a flat roof is under the current regulations to have a warm roof. Like other roofs insulating a flat one requires ample ventilation a vapor barrier and sealed bypasses. Why its important to insulate your flat roof. Insulated roof assemblies can be vented or unvented.

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. Cold roof a very bad idea. Unfortunately too many dwellings suffer from this problem. When you have an un insulated roof you have to live with.

Whatever new flat roof covering you choose epdm rubber kemper. Reduce extreme temperature fluctuations inside your home. Not cheap but needs to be done right either way. They lose loads of heat and are prone to leaking causing the materials to deteriorate.

However most cathedral ceilings and low slope flat roofs are insulated roof assemblies. To produce a hot roof rigid insulation is fitted outside above the weatherproofing. I explain problems with insulating a roof using the warm and cold roof construction methods. Fur down the rafters for more r value after evaluation air seal insulate and control the vapor diffusion.

In a nutshell you would sandwich 130mm of solid insulation between two decks allowing to place a vapour barrier on top of the first deck. Or insulate partially on the exterior side of the roof sheathing with an air control layer insulate in the rafters bays control the vapor diffusion and re work the fascia soffit etc. This is then covered with a further weatherproofing layer. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation.

Use rigid foam insulation panels on your flat roof before applying the final roof covering or inside the house before adding sheetrock or paneling. The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and insulation.