Insulation For Flat Roof Without Attic

This means lowering the height of the ceiling but may be a better option than insulating externally.

Insulation for flat roof without attic.

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. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. For a 1 inch board equivalent of 6 r value.

It is top quality and the most cost effective product for your flat roof. Rolls are easy to transport and can be cut to the length you need. Insulation on the floor of the attic figure 1. Leave a clear space between the top of the insulation and the underside of the roof sheathing to allow for roof ventilation.

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. 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. For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence. While expensive the best insulation is polyiso rigid foam.

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. It helps resist moisture that can lead to mold or mildew and provides increased sound and thermal insulation. 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. To insulate a flat roof internally using insulated plasterboard.

We recommend having at least 20 r value worth of material for optimal energy efficiency. Water is insulation s enemy. 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. 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.

Seal any roof vents into the parts of the attic that are not heated. Box out light fixtures.