Attic Insulation In Rafters Or Trusses

Ibc dictates acceptable placement and composition of roofing materials in chapter 15 but describes required thermal efficiency of the roof in chapter 13 which references the international energy conservation code iecc the minimum required thermal resistance varies.

Attic insulation in rafters or trusses.

Box out light fixtures. 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. In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face. Like many other building materials insulating spray foams for use on roof rafters and attic surfaces come with advantages and disadvantages.

Energy trusses are designed to allow greater insulation depths at the heel. Climb into the attic and measure the width between two roof rafters or trusses to determine the size of the rigid foam attic vents you will need to purchase. Water is insulation s enemy. Images courtesy simpson gumpertz heger.

Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. It can be cut to fit most joist spaces and is an affordable way to meet energy code requirements for air flow. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Most standard residential trusses can achieve r values r value referring to a rating that represents the insulation s capacity to resist heat transference from heated to non heated areas and vice versa of 11 or 13 near the sidewall.

Being lightweight they do not impose significant additional loads on existing structures. Where the insulation does not fill the total rafter depth the low emissivity foil facings can gain additional thermal benefit from the air spaces they face. The relatively costly application for example can also save money by lowering your energy bills and enabling you to add your own insulation with a contractor s help. The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs.

Use it between rafters to create an air channel through insulation to help keep air flowing freely in your attic. An attic conversion is a great way. Roof insulation configurations for unvented rafter truss assemblies.