Attic Insulation In Rafters Or Trusses

This board forms the bottom member of each rafter and of course the ceiling of the space below.

Attic insulation in rafters or trusses. The are similar to trusses in this regard. Insulating below the rafters normally people use mineral wool or insulation boards to insulate the rafter space. The joists might then be covered with osb or plywood to form an attic floor for storage. If you ve measured your attic space and feel you have enough room to accommodate living space chances are you have rafters or you have special trusses called attic trusses which create a large open space under the peak of the roof.

Insulation on the floor of the attic figure 1. 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. If you re considering turning your attic into conditioned storage or living space it s worth changing tactics to insulate between the rafters and wall joists instead of the floor. This is because the effects of thermal bridging are limited which also results in the elimination of melt lines on the roof surface in cold climates.

Insulation stops also known as attic baffles or rafter vents are designed to provide adequate air flow from the soffit vents to the gable or ridge vents in a home s attic. You can use rigid foam panels or do as tom silva does with nearly all houses these days. Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials. Ibc section 1203 3 outlines the only circumstances when a roof may have an unvented attic or enclosed rafter truss assembly.

Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. In unfinished space an attic insulation is typically laid between the joists. In the case of a cold roof structure the insulation is placed between or between and under the rafters or at ceiling joist level and the roof is ventilated by leaving a 50mm gap above the insulation which vents air to the outside. Encapsulating the rafter or top truss chord roof framing members with spray foam will improve the energy efficiency of the attic space.

By contrast conventional trusses have supports called webbing that zigzag through the attic space. If you are planning to use wool then it is imperative you wear protective clothing goggles and a face mask since the wool is an irritant. Hire a pro to install spray foam insulation. Attics are fresh air ventilated so provisions must be made to reroute the attic s ventilation through the rafter spaces and the rafters must then be insulated.

Although not expressly. This insulation strategy has not changed in recent code iterations and is not discussed in this article. New rules and practical interpretation.