Insulating A Flat Roof From Outside

Reduce extreme temperature fluctuations inside your home.

Insulating a flat roof from outside.

Unfortunately too many dwellings suffer from this problem. Many properties use this option as there are no additional costs for scaffolding or organising how to gain safe access to the roof exterior. 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. 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.

Why its important to insulate your flat roof. Like other roofs insulating a flat one requires ample ventilation a vapor barrier and sealed bypasses. Whatever new flat roof covering you choose epdm rubber kemper. Materials used to make insulation in these three types include mineral wool fiberglass cellulose fiber vermiculite styrofoam polystyrene and polyurethane.

However most cathedral ceilings and low slope flat roofs are insulated roof assemblies. They lose loads of heat and are prone to leaking causing the materials to deteriorate. Use rigid foam insulation panels on your flat roof before applying the final roof covering or inside the house before adding sheetrock or paneling. 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.

Insulated roof assemblies can be vented or unvented. Rigid foam panels are available in thickness. The material that works best depends largely upon preference in a given situation. Fur down the rafters for more r value after evaluation air seal insulate and control the vapor diffusion.

You would only do this however if replacing the roof covering on top and you have the height above the roof to do this. A roof over a vented unconditioned attic does not need to include any insulation. Cold roof a very bad idea. With this kind of roof the insulation follows the slope of the roof.

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. The correct method for a flat roof is under the current regulations to have a warm roof. The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and insulation. I explain problems with insulating a roof using the warm and cold roof construction methods.

This is then covered with a further weatherproofing layer. When you have an un insulated roof you have to live with.