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Figuring out the attic insulation you need

(ran HP, HC editions)

Question: Our home is more than 20 years old. It was built well and has been relatively maintenance-free for the 12 years we have lived here, but, when I was up in the attic the other day, I noticed that there didn't seem to be much insulation there. Does this mean that my attic isn't properly insulated?

Answer: You can't always tell how much insulation is in place by looking at it. What appears to be a lot of insulation or a little insulation may really have no effect on its performance.

It is the R-value of insulation that means the most. R-value is the term used to measure the resistance of the insulation material to the flow of heat, and knowing the R-value of your attic insulation is how you know whether there is enough there.

The first thing you need to do is find out what the recommended R-value is for attics in homes in your climate, which can vary tremendously. If you live in Central Florida, then attic insulation with a rating of R-19 would probably bethe minimum level you would want, but, if you live in New England, then R-38 or higher would probably be the minimum for a home in that climate. Your local county extension agent, a building supply store or a building contractor can quickly tell you the recommended values for your area.

Here is why this makes such a difference in figuring out what you have. Several inches of one type of insulation can be different in R-value from the same amount of another type. An inch of loose-fill fiberglass, for example, has an R-value of around 2.2. The same amount of fiberglass batts and blankets would have an R-value of about 3.1 per inch. Each inch of rigid board expanded polystyrene insulation would be rated at 4.0, and foamed-in-place urethane insulation would be rated at 6.2 per inch. Other types of materials would have their own values per inch.

To find out if you have enough insulation, you first need to determine the appropriate R-value for your area, then measure how much insulation there is and figure out its R-value.

Odds are good that much of what was installed in your attic 20years ago has settled a lot by now, opening up breaks throughout the material. Any time insulation gets compressed or settles too much, it starts to lose its effectiveness.

To work properly, insulation needs to give a continuous layer with no gaps, cracks or pathways for air to get through. Insulation can easily lose half its R-value if it gets compressed during installation or over time.

Plug up the leaks

Question: I would like to do home maintenance soon and have been reading labels on caulking material. I don't see any big holes or cracks in our walls anywhere, but I have read enough to know that openings are there and air must be flowing into and out of the house. How do I find these places?

Answer: I would start by checking out the usual suspects _ anywhere in your home where wires or pipes come in from outside, on exterior walls where things have been installed, on ceilings where there are recessed lights or other openings.

For example, take a close look around ceiling fans, water lines,switches and outlets. Check around exhaust fans in the kitchen and bathrooms. Look at penetration around the chimney.

Take a close look at the attic access door. Walk around the home, noting all the places where pipes and TV antenna wires go into the house.

Seal around these openings, and you ought to see a drop in your power bill the next month. Your house will be more comfortable too.

Energy tip

Use the appliances best suited for the job. If you want to toast some bread, for example, do it in the toaster rather than the oven. You will use three times more energy using the oven.

Think about times you have cooked something in the oven that could also have been cooked in the more efficient toaster oven or microwave and remember that the next time you do some cooking. It can make a huge difference in power usage.

Ken Sheinkopf is associate director for the Florida Solar Energy Center. Write to him at the Florida Solar Energy Center, 1679 Clearlake Road, Cocoa, FL 32922.