Q: I painted my entire apartment about five years ago and the living room ceiling started peeling shortly after. Last year I scraped off what I could, plastered the entire surface, then painted with an alkyd base point. Now large patches are peeling off again, including the plaster. What can I do to repair this old surface and make paint adhere?

A: Plastering over the entire ceiling was a mistake that will continue giving you trouble unless you get that thin layer of plaster off. For cracks or shallow defeats you should have used spackling compound, not plaster, and even then you shouldn't have covered the entire ceiling. Now you will have to scrapte it all off, as well as most of the old paint. Something underneath was causing the original problem, so as long as some of the old paint is left you are bound to have trouble. One way to eliminate the need for getting all the old paint off is to scrape off as much as you can, then have the ceiling lined with canvas. You can then paint over this just as you would over plaster.

Q: I have noticed moss growing on our newly laid brick patio floor - in the sun as well as in the shade. What can be done about this?

A: There are several ways you can get rid of this type of growth. One is to use one of the various chemical preparations sold in garden supply stores for killing weeds and other types of plant life. Another is to buy one of the fungicides sold by swimming pool supply houses to treat swimming pools and surrounding areas that are troubled with moss. In both cases, follow directions on the package, and keep pets and children away from the area after it is treated.

Q: We recently purchased a ranch house that is about 25 years old and the basement has a very pungent mildew odor. What can we do to rid ourselves of this smell, and is there anything we should do to keep it from coming back in the future?

A: An odor such as you describe means there is a problem with dampness which is causing the mildew. First inspect every part of the basement to see if there is anything damp or water-soaked stored thre. If the walls are paneled, look behind them, even if it means removing one or more panels. Then check for the sources of dampness and make sure you take the steps necessary to keep moisture from coming in. To get rid of the odor you will also need plenty of ventilation. On dry days open all the windows and use a fan to circulate the air. An electric dehumidifier will also help - as will mild heat to help dry things out. Baking soda spread around in shallow aluminium tins is also a great odor abosorber.

Q: The metal panel on the back of my refrigerator is held on with self-tapping metal screws. Several of them are losse and won't hold, so the panel vibrates when the refrigerator runs. I don't want to drill larger holes for bigger screws because I am afraid to drill into the box. Do you have a suggestion?

A: You don't have to drill larger holes to replace the screws with larger one. Just take the old screw to the hardware store and buy one just one size larger in diameter. Then screw this into the smae holes. It will take a bit more pressure on the screwdriver handle, but after pressing hard you wil find the screw ill enlarge the hole without too much trouble.

Q. Two years ago we put flock wallpaper in our bathrooms. Within six months mold started to grow. I washed the paper with a mild Clorox solution, but within a short time th mold was growing again. We installed exhaust fans to rid the bathrooms of humidity, but the mold continues to grow. I want to replace the paper, but am afaid the same thing will happen again. Do you have any suggestions?

A. Flock wallpaper is a poor choice for a bathroom because it tends to absorb and hold moisture, but chances are the trouble is being caused by the paste used to hang your wallpaper. If the paste used was not mildew-resistant, the mild started growing behind the paper and worked its way to the surface. I advice taking all the paper off, then scrubbing the walls with a solution made of one part fresh Clorox with three parts water. Add some powdered detergent, then scrub on and allow to set for a few minutes. Rinse with clean water. When hanging you new paper, use a vinal base paste that is resistant to mildew.

Q. My home in eastern Long Island faces the water and has a cedar deck about five years old that has never been treated.It is starting to crack and splinter. I have been advised to treat it with linseed oil by some, while others recommended a wood preservative. What treatment do you recommend to help preserve the wood?

A. I would not advise linseed oil - it tends to darken, and accumulates dirt and mildew. A wood preservative is your best bet. You can use it clear or add a pigment if you want to stain the wood or restore some color.

Questions about home repair should be addressed to: Home Imporvement Department, The New York Times, 22 West 43rd St., New York, N.Y. 10036. Only questions of general intrest can be answered in this column.