Q: We have bought a house that is about 70 years old. One of the problems we found is peeling paint on the large, multisectioned radiators. These have been painted many times, apparently first with metallic paint and then with many coats of other kinds of paint. This is all chipping. How can I remove the old paint, and what is the best way to repaint the radiators so they look respectable?

A: The only way to get the old paint off is with chemical paint and varnish remover. Choose a semipaste, water-wash type. The job is messy, so cover nearby walls and floor with plastic drop cloths. Brush the remover on in thick layers, allow it to soften the old paint, then scrape or wash it off according to the directions on the container. (The job will be much easier if you disconnect the radiators and work on them in the garage.) When all the old paint is off, apply one coat of metal primer, then paint with a flat or low-luster paint in the color of your choice.

Q: I know that gypsum wallboard should be treated before wallpaper is hung for the first time to prevent damage to the wallboard when the time comes to remove the wallpaper. Can you tell me how to do this?

A: Almost any type paint applied to the wallboard in a uniform coat will do the trick because it will seal the surface so the paper sticks to the paint rather than to the paper facing the gypsum board. However, in practice most professionals find the best kind of paint is interior primer sealer made for use on walls and ceilings. You could use latex but this would mean waiting at least a month or two before you can safely hang the wallpaper over it -- and even then there may be problems. I recommend an alkyd or oil-base primer sealer.

Q: We have renovated and decorated every room in our house, but I cannot seem to find any help with the problem of changing the color of the plastic counter tops in our kitchen. I'm told nothing can be done short of putting in new counter tops. Can the color be changed any other way?

A: You can paint them, but this means periodic redoing, and you will have to be careful about cutting or scratching the painted surface. A good epoxy paint will stand up for quite a while if treated with care, and that is what I suggest. Be sure to clean and sand thoroughly before painting, and follow directions on the can exactly.

Q: We have an elderly dog who has had several accidents during the night in the past few weeks. As a result we now have dark brown stains on our wood floor where the dog's urine has soaked into it. Is there any way to remove these stains?

A: A lot depends on how old the stains are, and on the finish that was on the floor. Try washing the floor with a dilute solution of ammonia and water (about 4 to 1) and then rinsing with plain water. If the stains are still there, try washing them with a solution of half vinegar and half water and then rinsing. If neither of these methods works, I am afraid you will have to scrap off all the finish and resand the floor. If penetration has been quite deep, the dark stains may have to be bleached out with wood bleach after sanding.

Q: The cedar shakes on our 16-year-old house seem to be worn in spots. The top portion of each shingle where it is overlapped by the one above has become paper thin. Do you think it is necessary to replace these shakes to prevent leaks, or is this how they normally weather?

A: Wood shingles and shakes do not wear the way you say yours are wearing. They may split, crack or curl, but they don't get thinner and thinner. I think the shingles are much the same thickness they were when installed. I don't think you need worry about leaks. Shingles are only the first line of defense when it comes to keeping out water, most of which is kept out by the waterproof building paper or sheathing material under the shingles.

Q: In my backyard I recently had an expensive redwood deck built. This was treated with wood preservative, then a coat of urethane varnish was applied. What should I do to protect the deck during the winter? Should I cover it with heavy plastic?

A: The best protection is to keep the finish in good condition. In other words, touch up the varnish and sealer as soon as they show signs of wear. I don't think covering with plastic will help. In fact, it may do more harm than good because it will trap moisture underneath and not permit the wood to dry when it gets wet on the underside. An overhead awning or similar covering will help, or you can build a framework over the floor and cover this with opaque canvas or plastic -- the framework will allow air to circulate underneath.

Q: I want to insulate part of the floor of my house where it is over the unheated portion of my basement. The basement has a finished ceiling of sheetrock. Rather than take down all the sheetrock so that I can install the insulation, would it be practical for me to open the ceiling at the ends and pull the insulation between the joists so it is lying on the gypsum board with the vapor barrier facing up?

A: There is nothing wrong with this method of slipping insulation above your ceiling, but problems sometimes arise in trying to slide insulation in from the end -- it snags and tears on projecting nails, ragged edges of exposed beam ends or other lumber, and even on large splinters. There may also be a problem with wiring or plumbing that is in the way. It is worth a try, but in case you run into trouble you may find it worthwhile to either remove the ceiling in the basement and then replace it after the insulation is in place, or call a professional to blow insulation into the spaces between the joists.

Q: How can we remove rust stains left on a concrete patio by a piece of machinery that was left standing in one place too long?

A: Sometimes you can remove the stains by soaking with a saturated solution of Oxalic acid crystals (sold in paint stores). Mix with hot water until no more will dissolve, then mop on over the stain and allow to dry. If it seems to be working, repeat, then rinse off. If this treatment does not work, try using liquid rust remover (sold in hardware stores). Spread on liberally, cover with paper towels, then pour more on. After 15 or 20 minutes wash off with water and repeat if it seems to be working.

Letters from readers with problems should be addressed to Bernard Gladstone in care of The New York Times Syndication Sales Corp., 200 Park Ave., New York, N.Y. 10017.