Attic Insulation – Do You Need More?

Adding attic insulation is the single, lowest cost, major project you can do to improve your home’s insulation. A constant temperature makes your home a more pleasant environment, saves substantially on short and long term heating and cooling costs and increases home resale value.

Before you forge ahead with what sounds like a great idea, determine if you home needs more attic insulation and, if so, how much. There are about three ways to answer that question.

The first is the common sense or intuitive method. If your house temperature fluctuates a lot, always seem cold and the furnace is constantly going on and off, better move to the next step.

That next step is a do it yourself energy assessment or energy audit.

The third option is to get a professional energy audit. There are professional companies that do this, or some community utility companies will actually do this for you. Your local power company may do an energy audit for a nominal fee and of course.

Let’s assume that you’re going ahead with the project and you’ve done the prep work, sealing plumbing vent pipes, fan exhausts and chimneys inside and out, as close to air and water tight as possible. Also confirm that any air leaks between room and closet ceilings and the attic and vents and soffits protruding into the attic have been air sealed. The DOE reports that 40% of lost heat leaves your home through tiny air leaks. Think of it as money going out through the roof.

To answer the question of how much insulation you need and what kind, you’ll need to know what’s up there now. The energy audit procedure will help with this.

If you’re doing this yourself, measure the depth of the old insulation in about half a dozen places. If you have fiberglass or rockwool batts or blankets, the R value will be printed on the facing. If they’re layered, add them up.

If you find blown in cellulose (looks gray, like crumbled pebbles and feels like dryed newspaper), or blown in rockwool (grayish, fibered with black spots and looks and feels fuzzy or like dirty cotton), then you’ll have to get the depth and do the calculation yourself.

DOE rough R value guidelines are:
Blown in loose fiberglass R= 2.5/inch.
Blown in cellulose R= 3.7/inch.
Blown in rockwool R= 2.8/inch.
Fiberglass batts or blankets R= 3.2/inch.
Sprayed in foam (no values given), Iceynene foam generally R= 3.9/inch.
Sprayed in polyurethene, generally R= 6.3/inch.

How much additional insulation you’ll need depends on a number of factors like airflow and windows, type of heating and the climate you live in. Look at the United States DOE website guides. Input new of existing home, type of house heating and the follow with your home’s zip code for their suggestions for attic insulation, wall insulation, for basements, and such. Their information considers both cold and heat.

Keep in mind when you’re planning,a  home energy audit is well worth the time and money. A large amount of airflow across or out a large number of windows, especially if they’re single pane, may be causing far more energy loss than your attic.

If fire resistance is a priority in your choice of an insulator, you can scratch off rigid foam boards and cellulose.

If during inspection, you find old perolite or vermiculite granual insulation, it could contain asbestos.

Precut fiberglass batts or four or eight foot blankets are an excellent choice for the novice and can be install by you as the homeowner, but compare if they cost more in your area than installed cellulose. With either choice, suit up in protective clothing.

Installed Icynene and polyurethane foam is another choice. Urethane is more dense, structurally figid, and has a higher R value. This sprayed foam professionally installed can cost more per square foot than others and is very messy to install. But either foam is superior to other insulations on a number of factors.

The energy audit will help you estimate material costs and energy savings over time. That information can also be found from some manufactures as well as the government.

An attic insulation DIY project is worth the effort. Count on spending time doing the prep work and air sealing. Some investigating and shopping for lowest prices is involved. But any homeowner knows how to do that.

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