Insulation For Flat Roof Without Attic

While expensive the best insulation is polyiso rigid foam.

Insulation for flat roof without attic.

Because most flat roofs don t have an attic crawl space or venting the insulation must go underneath the roof s covering on the exterior of the home or be placed on the inside of the home. Rolls are easy to transport and can be cut to the length you need. It is top quality and the most cost effective product for your flat roof. 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.

This means lowering the height of the ceiling but may be a better option than insulating externally. Try a spray foam insulation kit to fill cavities gaps cracks expansion joints and other sources of air leaks. We recommend having at least 20 r value worth of material for optimal energy efficiency. Water is insulation s enemy.

This insulation strategy has not changed in recent code iterations and is not discussed in this article. For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence. 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. To insulate a flat roof internally using insulated plasterboard.

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. 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. Insulation on the floor of the attic figure 1.

For a 1 inch board equivalent of 6 r value. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Seal any roof vents into the parts of the attic that are not heated. New rules and practical interpretation.

Box out light fixtures. Leave a clear space between the top of the insulation and the underside of the roof sheathing to allow for roof ventilation.