Insulation

QUESTION: My house has a 4-foot crawl space surrounded by lattice, with 6-inch paper-backed insulation in the ceiling. It is very cold in the winter, so I was thinking of putting up a plywood to stop any air movement into the house. Would that work?

ANSWER: Yes, it will work. The porch will still be cold because it has no heat, but it may make it easier to heat. A less expensive material to use it Tyvek. Stable it securely to the joists. The plywood will ass a little to the insurance value and will be a definite air stop.

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Question
I am insulating my attic floor. The joists are 2-by-6s, which means they are 5 ½ inches high. Everywhere I shop, the fiberglass insulation is 6 ¼ inches thick. If I put the insulation between the joists and then put down floor boards, would the compression of the insulation affect the insulation value? Rock wool is between the joists, nearly to their tops, and I do want to keep about half of the floor boards in the attic for storage space.

Answer
It is hard to measure the fluffy fiberglass, and the insulation you have is really 5 ½ inches thick, designed to fit snuggly between 2-by-6s but not too loosely nor too tightly. Any minor compression will make no difference in insulating value. But hold everything! That rock wool is OK to keep, so you can take up the floor boards in space that you don't need for storage. Then take off the paper backing from the insulation and lay it at right angles to the joists. Make sure there is no insulation in the eaves. If there is, take it out. This done, you will be in fair shape for insulation on the attic floor. Of course, be mighty careful where you walk.

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Question
I have installed through-the-wall air conditioners in three bedrooms, and they work nicely. I don't want to take them down in the winter, and was wondering how to insulate them both inside and out during cold weather.

Answer
Stores carry many kinds of weatherproof, insulating covers for the outside of the units. On the inside, if you cannot find a big cover, make a box frame big enough and deep enough to clear the unit. Then nail a Styrofoam cover on the box, fit the box over the unit and caulk it in place. You must cover the Styrofoam with plasterboard or other fire-resistant material.

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Question
I am insulating my turn of the century, three level Victorian. What is the best stuff to blow into the walls? The third floor is finished but not occupied, but it may be in the future. Should I do just the first two floors or the entire house?

Answer
A good blown-in insulation for the cost of cellulose, with fiberglass a close second in insulation value. Even better is a new foam called Iceynene, but is quite bit more expensive. By all means do the whole house.

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Question
Just how would you go about insulating a 1916 house with no insulation? It is aluminum sided.

Answer
I would remove the aluminum siding, and try to sell it. Blow cellulose into the walls. Then insulate the attic floor with 12 inches of fiberglass. Next, I would put up white cedar shingles that I would not have to be painted or stained in any way for the next 40 years.

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Question
My bungalow attic has a low overhead and knee walls about 5 feet high. I would like to insulate the knee walls, but the studs are only 2-by 2's, too small for standard fiberglass insulation. Is there something I can fill the space with that will give a reasonable insulative value?

Answer
Yes, Rigid insulation. One is Styrofoam, the other polyisocyanurate, a modified urethane that has two brand names: High R sheathing and Thermax. Install 2 inches of either material between the studs for a snug fit.

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Question
My attic floor has only 1 to 2 inches of cellulose between the joists. Would it be okay to roll our fiberglass insulation on top of that?

Answer
Well, it is and it isn't. It has to do with a vapor barrier. Sometimes insulation is put on an attic floor without a vapor barrier, and heat can be lost through the insulation and into the attic. Your first priority is to check under the cellulose to see if there is vapor barrier ( craft paper, foil or polyethylene). If there is, then put down the rolled fiberglass, If there isn't, put down backed fiberglass (insulation backed by a vapor barrier) If you really want to do it right, take up the cellulose and put down 6 inch backed fiberglass rolls or batts. It will also help cool the house.

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