Insulation For Flat Roof Without Attic

Box out light fixtures.

Insulation for flat roof without attic.

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. Water is insulation s enemy. 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. For a 1 inch board equivalent of 6 r value.

Insulation on the floor of the attic figure 1. This means lowering the height of the ceiling but may be a better option than insulating externally. It helps resist moisture that can lead to mold or mildew and provides increased sound and thermal insulation. We recommend having at least 20 r value worth of material for optimal energy efficiency.

Rolls are easy to transport and can be cut to the length you need. 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. It is top quality and the most cost effective product for your flat roof. This insulation strategy has not changed in recent code iterations and is not discussed in this article.

You can expect to pay about 55 100 sq ft. New rules and practical interpretation. Seal any roof vents into the parts of the attic that are not heated. To insulate a flat roof internally using insulated plasterboard.

While expensive the best insulation is polyiso rigid foam. Try a spray foam insulation kit to fill cavities gaps cracks expansion joints and other sources of air leaks. 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. Leave a clear space between the top of the insulation and the underside of the roof sheathing to allow for roof ventilation.

It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence.