H.L., Ocala, Fla.

A. Styrofoam under the roof will probably prevent that condensation, but as a rule Stryofoam, being flammable, should be covered by a fire-resistant material such as plasterboard, and that is impractical.

A viable alternative is not as expensive, if the roof is open at the pool level: Put a ridge vent on that gabled roof. Or, put a large vent at the peak of one gable end and install a fan to exhaust the moist air and keep the air moving. The way the roof is now, warm and moist air gets trapped under the ridge, and as it cools it creates condensation. Even if the gable ends are open, the air can be trapped and has to be moved.

Q. I have peculiar stains on the concrete apron around my indoor pool. They could be algae or a fungus of some kind, but they are brownish cream and about the size of a quarter. I tried full-strength bleach and Triple Action20, which did no good. How can I remove the stains, and with luck, keep them from coming back?

BILL JABLONSKI, Braintree

A. They may be stains from leaves and other organic matter left on the concrete for too long a time. But why they are quarter-size is a stumper. At any rate, try this: Sand the stains with coarse sandpaper and, if they come off, seal all the concrete with a masonry sealer or a semitranparent stain. The sealer should be renewed once a year, while the semitransparent stain may last and be an effective sealer for three to five years.

If you don't like the idea of sanding concrete, then try muriatic acid and water. The acid attacks lime in the concrete, which may remove the stains. Then seal the concrete. Mix equal parts acid and water, and always pour the acid into the water. Wear skin and eye protection -- and extra care -- when working with bleach.

Q. The concrete deck around my pool is getting badly pitted. What can I put on it to smooth it out and make it look better? It is quite an extensive deck, some 500 square feet, so any repair work would be a lot of work.

J.M., Lynnfield

A. There are several things you can do: Anything you do will be a lot of work on an extensive deck around the pool. In other words, there is no easy way, unless you pay for it.

1. Trowel on a layer of Top 'n Bond, a special mortar designed to go on in thin layers, up to 1/2 inch thick. If you use this material, be sure to give it a rough, anti-skid surface. To do this, float it with a wood float 15 minutes or so after laying the mortar. Floating means rubbing the surface with a wood trowel, called a float. If you did this with a metal trowel, you will get a smooth and very slippery surfaces.

2. Apply a bonding agent to the concrete, then cover it with two inches of standard concrete, then wood float it. This won't work without the bonding agent, which is a sort of glue designed to hold the two components together.

3. Have an epoxy covering applied professionally. This might be slippery.

4. Build a cedar boardwalk over the concrete. This is the biggest job but may in the long run be the most satisfactory. It would require installing 1 x 4 cedar sleepers on the concrete, spaced 12 inches apart, then applying cedar floor boards on the sleepers, spaced enough for drainage, and parallel to the length of the deck. With luck this will last 15 years. Or, use Trex or other artificial ``wood'' made of ground-up wood and ground-up plastic milk cartons. It is more expensive than the cedar but is likely to last longer. Neither the cedar nor the artificial wood needs staining, sealing, or painting. This wood deck would raise the deck by 1 1/2 to 2 inches or so, but you might be able to live with that.