Q: the stone above our fireplace is blackened after much use. What can we use to clean the stone, and is there a sealer we can put on to protect it without giving the stone a sheen?

A: You can clean the stone with a strong solution of hot detergent and water, scrubbing it on with a stiff bristle brush and then flushing the dirt away with water. There are various stone sealers you can buy from stone dealers and paint stores, but these will all darken the stone slightly (as it appears when wet), and will often leave a slight sheen on the surface.

Q: Can I insulate my hot air ducts so that I will get more heat upstairs with two-inch fiberglass and a vapor barrier? If so, do I put the vapor barrier next to the ducts or on the outside?

A: Insulating your hot-air ducts where they pass through unheated areas is definitely a good idea to conserve heat -- but you don't have to use the kind that has a vapor barrier. Most installers do use insulation with aluminum foil on the outside, but this is not really because a vapor barrier is needed -- the aluminum does keep the mineral wood from absorbing moisture, but its main function is to protect against shedding and absorbing dirt, as well as moisture. The insulation is normally installed by wrapping and securing with tape or wire, but where ducts fit between beams, the insulation can be stapled to the beams on each side.

Q: The grooved shingles on our house were originally a light tan and we subsequently stained them a dark green. The trim is white. We would now like to have the whole house light gray, but have been told that we cannot do this with stain, that we would have to use a paint. Is this true?

A: It is true that with a wood stain you cannot apply a light stain over a dark one and have it cover successfully. However, many companies, including the brand you have already used, make what they call a "heavy body" stain. This is a more highly pigmented stain that is actually somewhere between a paint and a stain. It will cover dark colors, even though a lighter shade is being applied, but you will probably need two coats. You can then get a matching paint for the trim.

Q: I have an air conditioner in the wall that I would like to take out; I would then close the opening. My house has three coats of plaster on the inside walls, and shingles on the outside. What material do I use to close the opening?

A: Start by framing out the opening with extra 2-by-4s or 2-by-6s, whichever is needed to equal the thickness of the existing wall. On the inside you can then cover this framework with pieces of plaster board or gypsum board after nailing thin shim strips of wood underneath it if needed so that the inside face will come flush with the plaster walls. The seam between the plaster and the new board can then be filled with joint cement and perforated tape.On the outside it may be hard to get matching shingles, and it is difficult to fit them in so they will match perfectly with the old one.

But if you want to try, you can buy shingles from the lumber yard. You will have to pull a few of the old shingles off above the opening so you can slide now ones in from underneath. A much simpler method would be to cover the outside with exterior plywood, then paint this to match the shingles.

Q: My house is about 40 years old and is built on a cement slab foundation. The floors are hardwood, supported by 2-by-4s on top of the slab. What can I do about squeaks that have developed in these floors since the recent spell of cold weather?

A: The squeaks are caused by boards that move up and down slightly. As they rub, they make the squeaking noise you hear. In your case, if it is only the actual finished flooring that is loose (some boards may have buckled or shrunk slightly), then the cure is simple: Locate the specific boards that squeak, then drive additional nails in at an angle along the joints. Use a nail set to countersink the heads. However, if the 2-by-4s underneath have worked loose, you may have to rip some of the flooring up to get to them.

Q: The paint is peeling from the wood shingles around the outside of my house. The shingles were originally stained by the builder. The last time a latex paint was sprayed on. I contacted the paint manufacturer who said the peeling was caused by moisture. The manufacturer said I should scrape to the bare wood, then prime the shingles and repaint.

The painter who did the job said priming was not needed. He has agreed to re-do the job for half the price if I pay for materials. Which way should it be done?

A: If you're going to repaint again, I would recommend a primer, but only if a thorough job of scraping is done.I would also recommend brushing instead of spraying -- the brush will rub the paint into the grooves of the shingles better in most cases. The best way to minimize peeling, however, is to use stain -- but this means getting all the paint off first.