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Handyman on call

Adding attic insulation to a house from the 1960s

By Peter Hotton
Globe Staff / May 13, 2010

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Q. I have a ’60s-era house with 1 1/2 inches of insulation in the attic floor under plywood. I’d like to keep half the attic for storage. Would it help to add insulation to just half the attic? In the half that I use for storage would it help to take out the old and add 3 1/2 inches?

MIKE, in Hotton’s chat room

A. It’s strange that a ’60s house has such little insulation. But that was before the first big energy crunch in the late ’70s. For adequate insulation, you should add a minimum of 6 inches of insulation. To do that, take off the plywood and add 8 inches of fiberglass insulation (it’s called Polywrap) to the insulation between the joists. Put the plywood back where you want storage space. Then add up to 24 inches of fiberglass to the rest of the floor. Do not allow insulation to go into the eaves. Insulation in the eaves can cause significant moisture problems.

One more thing. To do a better job, find out if there is a vapor barrier (foil or a Kraft paper) under the insulation. If there is, then go ahead with what I just said. If there is not, take out all the insulation and lay down a polyethylene vapor barrier between the joists, then add the insulation.

The insulation alone will make a big difference in your heating bills. Adding a vapor barrier will be even better.

Q. I have ants in my kitchen, only one here and there, but they are a nuisance. I see a few in other rooms, as well. How can I keep them away? Ant cups were not much help.

FRAN, from Arlington

A. They are nothing to worry about. Just sweep them up and toss them outdoors. They are looking for food and warmth. The ant cups may have done more good than you think, so keep using them, but renew them every month. Or sprinkle a bit of boric acid along the baseboards, as little as practicable.

Q. Is reglazing an old bathtub a good way to bring back the finish? It’s a cast-iron tub, pretty sad and soiled looking.

CONCERNED A. That tub is the best you can get, and the porcelain enamel finish is not gone, but dulled by many years of scrubbing with abrasives like the old Ajax and the old Comet. Reglazing is done by applying an epoxy finish, so it is not really reglazing but covering the finish. Reglazing is a legitimate service, but try this first: Wet the surface with hydrogen peroxide, then sprinkle lots of cream of tartar (sold in grocery stores) on the wet surface, and wait overnight. Then scrub and rinse. You can make a paste of the materials, then apply it to the surface of the tub, wait overnight, then rinse. If that works, you have saved several hundred dollars. If not, then consider the epoxy finish.

Q. I would like to put down a floating hardwood floor on my concrete slab on grade, but there are differences in the levelness of the slab of 1/8 to 1/4 inches. Can I put the underlayment leveling compound on vinyl-asbestos tiles?

MIMI

A. The leveling compound might work because the non-asbestos part of the tiles has a cement-like consistency, and makes up most of the tile. But wait, you might be able to put the floor down without any leveling compound because those differences are very minor. The floor may depress a bit while walked on, but that is minor, just as are the differences in levelness.

Q. How often should I have my hot air ducts cleaned? I am a clean freak and can see a thin film of dirt on everything. The ducts have not been cleaned since 1989.

GUEST, in Hotton’s chat room

A. Clean them once a year, if it makes you feel better. Once every five years is a more sensible time schedule. If you are getting an odor from the ducts, such as mold, that is definitely cleaning time. If you clean the ducts, I’ll bet you will still get a film of dirt.

Globe Handyman on Call also appears in the Sunday Real Estate section. He is available 1-6 p.m. Tuesdays to answer questions on house repair. Call 617-929-2930. Hotton (photton@globe.com) also chats online about house matters 2-3 p.m. Thursdays. Go to www.boston.com