Prevent Floor Buckling From Moisture in Slab

QUESTION: I would like to install a strip oak tongue-and-groove floor on top of an above-grade concrete slab. However, I’ve heard horror stories of costly wood floors buckling from moisture. How can I avoid problems caused by moisture that might accumulate in the area under the slab?

ANSWER: A hardwood floor can be installed on a concrete slab at or above grade. The Oak Flooring Institute recommends against below-grade installations.

Moisture is the chief culprit in hardwood floor buckling, so test the slab for dryness. Tape one square foot of clear polyethylene sheet to the slab, sealing its edges with plastic tape. If after 24 hours, no clouding or moisture droplets have formed under it, the slab is dry enough to install a wood floor.

To prevent moisture from reaching the underside of the hardwood floor, place a vapor barrier of either building felt or polyethylene plastic over the slab prior to installation.

Use Heat to Restore Contact With Formica

Q: Our Formica kitchen countertop is glued onto a fir plywood backing. Over the years, the contact cement has let go in spots. Formica is also glued tightly along the edges. Can a glue be injected between the Formica and the plywood to reglue them, even though old contact cement is still there?

A: Your countertop is probably loose because someone periodically places a hot pot on it. When the temperature goes above 150 degrees Fahrenheit, the contact cement softens and starts to let go. If the contact cement is not too old, it may be reactivated by heating the area with a gun-type hair dryer.

You need a temperature of about 200 degrees on the surface of the Formica to reactivate the cement. Then roll the area with a board clamped in place or weighted sufficiently to hold it in place and the contact cement resets.

If your contact cement is aging and cannot be reactivated, you can bore a tiny hole into the unstuck area from the underside of the plywood. Take special care to bore deeply enough to penetrate the plywood but not far enough to come through the Formica.

Inject white wood glue into the unstuck area. Then, push the loose section of the countertop up and down to spread out the glue. As before, cover the area with a board clamped or weighted to flatten the Formica until the glue dries completely.

Accumulated Paint Needs a Cleansing

Q: The outside of my home is covered with wood-grain aluminum siding. In a few areas, the bottom edges of the siding have developed a white chalklike substance. What is it, can I prevent it from spreading and how do I remove it?

A: The chalky substance is a layer of dead paint pigments along the bottom edges of the siding. It is not aluminum corrosion. Over time, the siding’s paint weathers, developing a dead pigment layer on the surface. Particles of dead paint are washed off by rain and accumulate along the siding’s bottom edges.

Wash the siding periodically with a solution of one-third-cup detergent, two-thirds-cup triphosphate (such as Soilax), 1 quart Clorox and 3 quarts warm water.

For further information on any home problem, write to Popular Mechanics, Readers Service Bureau, 224 W . 57th St . , New York, N . Y . 10019.