Insulation For Flat Roof Without Attic

Try a spray foam insulation kit to fill cavities gaps cracks expansion joints and other sources of air leaks.

Insulation for flat roof without attic.

While expensive the best insulation is polyiso rigid foam. It is top quality and the most cost effective product for your flat roof. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Depending on your climate you ll need r 30 to r 49 to meet code which is 5 to 8 1 2 inches of polyiso rigid foam which is r 6 per inch.

This insulation strategy has not changed in recent code iterations and is not discussed in this article. Seal any roof vents into the parts of the attic that are not heated. Leave a clear space between the top of the insulation and the underside of the roof sheathing to allow for roof ventilation. Box out light fixtures.

In most cases it should be possible to insulate each rafter space all the way down to the eaves and over the top of the exterior wall. To insulate a flat roof internally using insulated plasterboard. It is important to note when insulation is on the floor of the attic the space between the insulation and the roof deck must be vented to the exterior. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.

Water is insulation s enemy. This means lowering the height of the ceiling but may be a better option than insulating externally. Insulation on the floor of the attic figure 1. New rules and practical interpretation.

But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used. Rolls are easy to transport and can be cut to the length you need. We recommend having at least 20 r value worth of material for optimal energy efficiency. You probably don t have to meet code of course retrofitting insulation on a funky old house but it s not a bad thing to strive for.

It helps resist moisture that can lead to mold or mildew and provides increased sound and thermal insulation. For a 1 inch board equivalent of 6 r value.