Small and Medium Sub-area Upgrades

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Subareas—basements and crawl spaces—are a prime target for water damage, from both surface water infiltration and from condensation. These do-it-yourself projects can prevent or inhibit such damage.

Reducing Water Infiltration

Surface water resulting from rain, melting snow, and irrigation can wreak havoc on structures below ground. Basements that don’t leak are that way because the surface water is effectively directed away from the house at ground level or because the exterior surface of the basement walls and floor were waterproofed before the concrete was poured.

Because surface water is a major cause of leaks and floods in subareas, the abutting earth at ground level should be graded so that it slopes away from the subarea walls. Surface water will then flow away from the house, where it can soak into the earth without doing damage. You can also add a French drain to help keep water from entering the subarea.

The most cost-effective time to grade the earth and add a waterproof barrier is during construction. It is not practical once the walls have been completed and backfilled with dirt. Although waterproofing the inside surface is not as effective as waterproofing the outside in terms of stopping water, you can reduce moisture and humidity in the subarea with a coat of epoxy paint. Make sure that the walls are clean before you apply the paint (see the next section). Be aware, however, that hydrostatic pres sure can sometimes be so great that even epoxy paint will not hold back the water.

Cleaning Efflorescence Off Concrete and Wood

Efflorescence occurs when water passes through concrete, stone, or wood and leaves a powdery white residue of mineral salts on the surface as it evaporates. When found on masonry basement and sunken garage walls, the residue is mainly an aesthetic problem.

To clean efflorescence off concrete or stone, use a 10 per cent solution of muriatic acid (1 part acid to 9 parts water) and a stiff nylon brush.

Caution: Muriatic acid is caustic and should be used with plenty of ventilation, eye and hand protection, and protective clothing. Also, when mixing caustic chemicals, such as muriatic acid and lye, with water, follow the three-A rule of basic chemistry: Always Add Acid (to water). Never add water to a concentrated chemical—the re action can cause splattering, fire, and even explosions.

Efflorescence on wood, especially in a poorly ventilated subarea, indicates the presence of water and the possibility of fungus growth. Using an ice pick, prod any wood on which you see efflorescence. Soft wood indicates that fungus damage is taking place.

If you find efflorescence but the wood is still in good condition, a simple cleaning-and- treating project can inhibit further damage. First, use a wire brush to clean away the mineral salt. Then paint the cleaned area with a copper naphthenate preservative that will reduce the chance of fungus damage. As with any pesticide, follow the directions and handle with care.

Inhibiting Condensation and Mildew Growth

Damp, cold soil in the subarea can contain enough moisture to condense in large quantities on the subfloor and cause serious mildew and fungus damage.

If the soil in the subarea is cool and damp, cover the ground in the subarea with a layer of 6-mil plastic sheeting, either black or clear. Lay it as flat as possible against the ground, and tape all joints in the plastic together with 2- inch-wide duct tape. Also use the tape to seal holes where penetrations have to be made around plumbing pipes and concrete piers. Any vapor that's created will condense on the underside of the plastic instead of the subfloor.

Condensation is less apt to occur when the area is well ventilated. You can simply add more foundation vents, up to double the original number.

Nail-on foundation vent covers are available that will fit most floor-framing members; confirm available sizes prior to cutting. To install a vent, cut a rectangular hole at the point between the foundation and the wood floor at the perimeter of the house. Use a drill to make a hole at each corner of the rectangle to be cut, and then complete the cut with a reciprocating saw or a handsaw. Do not cut vents in the sup ports below window and door headers.

Preventing Subarea Pest Damage

The best way to keep pests such as mice and gophers out of a subarea and also make it less prone to fungus damage is to spread a thin layer of concrete on the ground throughout the entire subarea. The concrete should be poured over a layer of 6-mil plastic sheeting (see previous section) to pro vide a moisture barrier.

This upgrade is easiest and most cost-effective in homes with full basements or at least sufficient clearance between the earth and the underfloor; otherwise extensive digging is necessary, making this upgrade costly and time-consuming. You can use a pump to transport the concrete quickly and easily into the subarea; then spread the material evenly and smoothly over the ground with a trowel or wood block.

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Updated: Friday, March 11, 2011 0:34