There are many types of insulation. The most common type is batt, or blanket-type insulation (typically fiberglass). This is the least expensive, but requires careful installation to ensure 100 percent coverage. Blown types, such as fiberglass, cellulose (made from recycled newspaper) and foams are more easily installed and do a good job at filling in gaps, cracks and areas around pipes and wiring. Foams have an added benefit: They air seal all the gaps and cracks in the walls for more of an airtight outcome. Below is an insulation checklist.
• Insulation should be installed to be in full contact with the air barrier (the Sheetrock to the inside and the sheathing to the outside) to provide continuous alignment of the insulation with the air barrier.
• Insulation should be installed to fill 100 percent of every cavity.
• Insulation should be cut to fit around all plumbing, heating, electrical penetrations and other obstacles. This should fill all cavity spaces and gaps, while not compressing the insulation.
• If batts are used, they should be split to go behind and in front of wires and plumbing.
• The space behind electrical boxes needs to be fully sealed and insulated.
• If faced (Kraft or paper) batts are used in walls or cathedral ceilings, the flanges must be stapled to the face of the studs or rafters, not the side of the surface facing into the cavity.
• Attic insulation should extend to the exterior edge of the top plate of the wall below. Roof-framing details, such as raised-heel trusses or oversized trusses, must allow for this.
• Insulation baffles or other air barrier should be installed to prevent overblow into soffits and to prevent wind washing through the insulation. This means that baffle height must be no less than the thickness of the insulation.
• Attic-access openings (hatches or pull-down stairs) should be insulated to at least R-30 and weather-stripped to prevent air movement between the attic and the living space. The insulation must be glued or stapled to prevent misalignment. This is a great application for rigid foam.
• Floor insulation must be in continuous contact with the subfloor above. Floor insulation shall be installed so as to provide continuous coverage, with no compression of the insulation and with no gaps. Batt insulation must be cut to fit around pipes, blocking and bridging and other obstacles, so as to provide the full R-value in all spaces.
• Band joists are insulated to at least the level of exterior walls and cover the entire band-joist area.
• Walls between conditioned space and attic space, such as knee walls in bonus rooms, should always have a rigid material on the attic side, preferably rigid foam insulation, which will prevent air flow through the wall cavity and allow the R-value of the wall insulation to perform as intended. This rigid material must be sealed with caulk or spray foam at all connections to the framing.
• Use single-ply headers where possible to allow for insulating headers above windows and doors. It is possible to insulate headers by using foam sheathing instead of plywood or oriented strand board as a spacer, either between or on one side (preferably the exterior) of double headers. All headers should be insulated with rigid foam insulation (minimum R-3, i.e. half-inch foam board between two two-by-tens).
• Ladder “T-walls” should be used at partition connections on exterior walls in order to maximize the area of insulation on that exterior wall.
• Outside and inside corners: Two-stud corners or “California corners” should be used to decrease lumber use and increase possible insulation levels, compared to typical practice. Wood nailers and/or drywall clips should be used for ease of installing exterior and interior finishes.
Sources for this checklist included Advanced Energy System Vision Guidelines, Southface Energy Institute Technical Bulletins, HealthyBuilt Homes program guidelines and Energy Star guidelines for homes and indoor quality.