How To Insulate A Flat Roof From The Outside

The foam insulation can be put directly over the shingles or the shingles removed if there is a weight consideration.

How to insulate a flat roof from the outside.

To make installation of the foam easiest screw a board over the very bottom of the existing roof edge. The correct method for a flat roof is under the current regulations to have a warm roof. This is then covered with a further weatherproofing layer. Lots of traditional flat roofs are of the cold roof construction type.

Cold flat roof insulation. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. Warm flat roof insulation. With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top.

This means there is a vapour control layer in the ceiling and cross ventilation at the eaves or the top of the walls. If you want ventilation channels between the top of the insulation layer and the underside of the upper layer of plywood roof sheathing an unnecessary step in most cases but useful in some climates to reduce the chance of ice dams a problem that does not generally affect standing seam roofs the usual method would be to create a ventilation channel by installing 2x4s on the flat 16 inches or 24 inches on center from soffit to ridge in other words the 2x4s are perpendicular to the. To produce a hot roof rigid insulation is fitted outside above the weatherproofing. 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.

Thermalwall ph rigid eps insulation board for insulating the exterior walls of homes. This is probably the most popular method for commercial roofs but can be utilized for residential flat roofs also. Insulating on the exterior roof surface. This will enable the airflow to circulate freely.

The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and insulation. Bypasses are anywhere that there is a break in the insulation. Just make sure there is no rot in the roof deck before closing that all in with nice warm insulation. This is done by applying a strong adhesive to the foam board laying it down on the roof surface and securing with washer head nails.

If insulation is being added to an older building then it is common practice for the ceiling itself to be taken down. You would only do this however if replacing the roof covering on top and you have the height above the roof to do this. This may help with condensation but causes such a loss of heat that it has been banned in scotland. This could be a hole crack or other kind of unprotected space that the insulation does not cover such as around a light fixture.