Unfinished-Attic Insulation Upgrade
Seal air leaks first, then blow in extra insulation for an energy-saving improvement that offers a great bang for the buck.
Synopsis: Although it’s easy to think of big things when you’re looking for places to cut energy costs (replacement windows, anyone?), the first steps to take involve insulation in your home. FHB contributing editor Mike Guertin guides you through some relatively low-cost techniques for upgrading your home’s insulation. He begins by sealing air leaks, such as the gaps around recessed lights and electrical boxes, plumbing or electrical chases, framing and a chimney, and more. Guertin includes a guide to finding the best air sealant for the job. He then recommends tuning up existing insulation, whether fiberglass batts or loose-fill cellulose. In conclusion, Guertin outlines the process for blowing in loose-fill insulation, which he says is a two-person job.
Magazine extra: Watch Mike use the Owens Corning AttiCat system to blow fiberglass insulation into his own attic during an energy upgrade.
Do you want to keep your heating costs from going through the roof? It’s easy: Keep your heat from going through the roof. Saving money on heating-fuel costs is a lot simpler than negotiating with OPEC or your local utility. On a recent upgrade in the attic of a 1950s-era house (one of two projects shown here), I air-sealed and spread a 12-in.-deep layer of cellulose throughout 1500 sq. ft. of space in about a day. Coupled with other energy-saving improvements made to the home, the result was that the owner saw his heating and cooling costs reduced by half compared to the previous year, even in the face of higher electricity and heating-fuel costs.
I typically focus my efforts to improve the energy efficiency of an attic on two main areas: sealing air leaks in the ceiling and increasing the amount of insulation.
The payback period for tightening a leaky ceiling can be as short as a month. Adding insulation might take a few heating or cooling seasons to pay off, but the wait is relatively brief. I estimate the payback for air-sealing and upgrading attic insulation to be realized in three years.
On these projects, I also chose to install a radiant-reflective membrane. Besides reducing radiant-heat gain from the roof, the membrane makes the attic more attractive and dust-free for storage use, and it keeps the blown-in insulation from blocking the rafter bays. While they can reduce peak attic temperatures by 10°F to 30°F, the barriers haven’t proved to be cost effective in all geographic regions, or in attics that are adequately insulated, that are air-sealed, and that have well-insulated, wrapped air-handling equipment and ductwork. You are probably better off spending the money on more insulation and air-sealing than on a radiant barrier.
Stop the air leaks, stop losing heat
Air leaks can account for 30% of a home’s energy loss, so it pays to seek out and seal every penetration between the living space and the attic before adding insulation. Don’t leave any batt unturned when hunting down air leaks. Dust deposits in leaking air stain insulation brown or black, so you can start by looking for discoloration in the insulation.
I treat the drywall ceiling as the air barrier and seal all penetrations, joints, and holes. The open framing for soffits and chases is a highway for air leaking from wall cavities into the attic. Another gaping hole is the attic-stair bulkhead.
I install an insulated and gasketed cover for the attic access panel or pull-down stairway. you can buy a ready-made access cover, or you can make your own. The cover can be fit within the riser or on top of it. When the cover sits on top of the riser, apply the gasket material (usually adhesive-backed foam tape) to the cover (not the floor) so that it’s not damaged when someone accesses the attic.
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