Insulation is necessary, but don’t go overboard

Insulation is a topic that can make your eyes glaze over. For most homeowners, it gets too nitty-gritty. After all, insulation can be foam that’s injected into walls. Or big batts made from materials like fiberglass or rock wool that can be rolled out in your attic. Or loose-fill material made of fiberglass, rock wool or cellulose that can be blown into spaces using pneumatic guns. It goes on and on.

So what is “good” insulation, and what type of insulation do you have? And when do you need to add insulation to an older house? And what is inside your walls anyway?

ON THE HOUSE

The basics

In the desert, homeowners mainly worry about having enough insulation to keep out summer heat, but insulation works year-round. Even in southern and central Arizo- na, we have temperatures that drop below 32 in winter. Good insulation can help keep you warm and keep your pipes from freezing. In addition:

» Insulation keeps your home quieter by absorbing outdoor noises.

» It protects during a fire because insulation stops air leaks that can make flames spread. That’s why insulation needs to meet fire-safety standards.

» It prevents a heating or AC crisis from getting worse. For example, a cooled-down, properly insulated house will heat up slowly while you’re waiting for that repairman to drive up.

To measure the quality of insulation, contractors use the R-value, which you will also find on packages of insulation. The higher the number the more resistant to heat transfer the product is, but just shooting for high R-values can be counterproductive.

According to the U.S. Energy Department, R-13 is the standard

for walls and R-38 for attics in central and southern Arizona, no matter what insulation you have. You can go higher than the recommended numbers, but the additional benefits would not be cost-effective. R-values should be higher in mountain areas and higher elevations.

If you think your insulation is not working very well, you can go up in the attic to inspect and measure its depth. Fall is a great time to climb the ladder and go up there.

Downstairs it’s trickier; you probably have to chop a hole in the drywall in an outside wall to see what you have and whether it is deteriorating.

That’s not likely to be something many of us want to do, so most homeowners obsess about their attics, which can be the primary culprit in an uncomfortable home or the biggest factor in high energy bills.

The best starting point: Hire a professional to do a whole-house energy audit.

There is still a small tax credit available from the federal government for installing insulation. Some utilities, such as SRP and APS, offer rebates for improving insulation as well.

Let the pros go up in the attic and check out the insulation; they’ll also run tests on your air ducts, windows and doors to find out what other energy leaks you might have. SRP and APS will help foot the bill for this service; check out their Web sites.

Frame construction

Inside the average frameconstruction Arizona house, you’ll find fiberglass insulation in walls and ceilings/attics.

Unless it was a custombuilt home where the owner wanted something else, fiberglass batts are the construction industry’s standard material.

Most framed homes built here in the past 20 years probably have sufficient insulation. But if your home is older than that, you could have issues to deal with. And as your home ages, insulation can age and deteriorate just like your carpet, your paint job and your kitchen appliances.

Fiberglass batts can be rolled out over existing insulation or loose-fill insulation can be blown in. It is important that insulation is in contact with the wall board that comprises the ceiling. If there is a gap, much of the insulation value is lost. There should be no spaces between the insulation batts, and the insulation should stretch all the way to the eaves. Any attic insulation must be properly ventilated.

Fiberglass insulation can also be blown into walls using pneumatic equipment, but that will be a bit more expensive and requires making holes and patching them afterward.

Masonry homes

But tens of thousands of homes in Arizona can have special problems. Back in the 1950s, ’60s and even ’70s, for example, many ranch-