Q)The stucco on my 23-year-old home, which is built on a concrete slab floor, is flaking away in an irregular line about 7 to 14 inches above the ground. I plan to repaint the house. Should I treat the flaked surface before I apply patching stucco and paint? -- J.B.

A)Any open cracks in stucco will tend to admit moisture beneath the surface. This is probably what is causing the flaking. Left unattended, this will lead to more problems, such as rotting wood underneath the surface or more loose stucco. Thin cracks and small damaged areas can be patched with premixed dry mortar mix (available at most hardware and lumber yards).

First, thoroughly clean any loose debris out of the cracks. Use a hammer and cold chisel to carve out the bottom portion of the cracks (so the bottom is wider than the top). This is called undercutting and prevents the mortar patch from falling out after it has dried. Mix the mortar and moisten each crack before applying it. Force the mortar into cracks with a triangular masonry trowel. Fill each crack to the level of the surrounding wall surface so it matches the texture of the wall.

If your flaking foundation has developed areas that need larger patches (up to a foot across) a different technique is required. As with smaller cracks, gouge and clean out all the loose stucco. If the damage is deep, you need to take it down to the wire mesh (about three layers deep). If the mesh is badly rusted, it should be cut out and a new section nailed in. There should be waterproof building paper behind the mesh and against the wood house wall. Replace the paper if it is damaged. The mesh should be nailed so that it's out about 1 1/2 inches from the wall surface. Special "lath nails" are made for this. The spacing allows the wet mortar to squeeze behind the wire.

Two coats of mortar will be sufficient to make the patch. Trowel on the first coat over the wire mesh and bring it to within one-half inch of the surrounding wall surface. Let set for an hour and then rough up the surface, making horizontal scratches with a long nail. The roughness provides the second coat with a surface to adhere to.

Allow the first coat to cure overnight (dampen it periodically to slow curing and add strength). Trowel on the finish coat, bringing it up to the level of the surrounding wall. After the surface sets for one hour, tool it to match the texture of the existing wall.

Dampen the finish coat several times a day for several days. When thoroughly dry, apply a sealer coat prior to painting. Be sure to select a sealer for masonry finishes.

To protect the lower walls of your home, make sure that there is adequate drainage away from the foundation, and that gutters carry water off the roof and away from the house. Avoid putting plants near the foundation that would require frequent watering.

Q)Four years ago I installed a dead-bolt lock using "one-way" screws. I need to replace the lock. How do I take out the screws? -- J.O.V.

A)If the screw heads are flush with the hardware, use a power drill with a drill bit that is slightly smaller than the screw head. Drill a pilot hole in the center of the screw head. Then insert an "easy out," a corkscrew type of tool that, when placed in the pilot hole, will tighten as you turn it counterclockwise and back the existing screw out. If the heads on the one-way screws are not flush, you may be able to get a firm grip on the heads with vice grips and back them out.

Q)An old and strong tree beside my parents' garage has grown so big that the roots have cracked the concrete driveway and have made it difficult to shut the garage door. I've been advised to dig a trench around the tree and put cement in it. Will this work? -- H.V.S.

A)I would not advise this. It is likely that this tree has a deep and extensive root system. Cracking concrete and foundation damage are common problems with trees that have been planted too close to houses, driveways or patios. Your best solution probably is to remove the tree before its roots cause more damage.

Q)Our custom-built home was completed in 1969. We have three American Standard Vent-A-Way toilets. They are beginning to malfunction and parts are difficult to get. Can these toilets be converted to conventional types? -- R.A.A.

A)You need to ask a plumber for an assessment. It would seem, however, that installing new toilets may be a less expensive and longer lasting solution than changing the old ones. Send inquiries to Here's How, Copley News Service, P.O. Box 190, San Diego, Calif., 92112-0190. Only questions of general interest can be answered in the column.