Flat Roof Ceiling Insulation

There are two main types of flat roof that require different approaches to installation.

Flat roof ceiling insulation.

With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top. The typical u value of an existing uninsulated flat roof is 1 5w m2k. In fact it may cause damage in the long term. Insulation is placed in between the joists underneath the roof surface.

For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence. It s what s called the cold roof principle. Your two best options are spray foam insulation on the underside of the roof sheathing an installation which will require the ceiling to be removed at least partially or the installation of rigid foam on top of the existing sheathing. We recommend having at least 20 r value worth of material for optimal energy efficiency.

Vapor barriers are usually made from polyethylene film asphalt laced building paper or paper backed aluminum. It should be of the maximum available thickness. It makes no difference which way the heat flows through it. You can expect to pay about 55 100 sq ft.

Flat roof insulation thickness the chosen insulation laid on top of this should be able to take the weight of anything put above it on the roof without compression or protected from compression by further sheeting. 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. Can a flat roof be insulated from inside from the ceiling of the area below. While expensive the best insulation is polyiso rigid foam.

Flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options. This system was often used in the past but is not recommended nowadays. The correct method for a flat roof is under the current regulations to have a warm roof.

As a matter of fact thermal resistance works the same way. Flat roofs or low slope roofs should be unvented. Insulation material is placed on top of the roof rather than in between the ceiling and the decking. Insulating a roof from inside is technically feasible.

The air pockets inside the insulation traps the heat. For a 1 inch board equivalent of 6 r value. Ceiling insulation is excellent for resisting convected and conducted heat. It is top quality and the most cost effective product for your flat roof.