DIY Quick Tips

HOW TO PAINT EXTERIORS

SURFACE PROBLEMS

A house exterior takes quite a beating from nature-UV rays, high winds, freezing temperatures blistering heat-and the one thin film that protects and preserves the surface is paint. Moisture, in various forms is constantly present in the atmosphere and tends to accumulate beneath a coat of paint. It is responsible for blistering, peeling staining and mildew.

1. BLISTERING AND PEELING
Excessive moisture in the wood surface is the culprit. The moisture can come from: Uncaulked cracks and joints, Worn or crumbling caulking, Ice or debris-filled gutters, condensation on interior of a cold exterior wall.

SOLUTION
Eliminate the source of the moisture. Examine the house exterior and make repairs to gutters, roofs, windows trim, joints and siding, etc.
Proper caulking is important; it is important to apply new caulk to a dry, primed surface. If you do not seal the wood with a coat of primer; it will absorb the caulking vehicle (that ingredient that allows it to be pliable and spreadable) and cause the caulk to dry out.

2. CHECKING AND CRACKING
Checking and cracking develop when paint begins to lose its elasticity. Checking results in a pattern of short narrow breaks on the top layer of paint; cracking occurs later as these breaks deepen and split. The split in the film allows moisture to enter and loosen the paint. Newly applied, paint is remarkably flexible and can expand and contract with changes in temperature and humidity. On older homes with numerous coats of paint, the underlying paint layers become brittle with age and are no longer flexible. As the wood swells, stress breaks the bond between layers to form checks. More activity widens the breaks to form cracks.

SOLUTION
Remove as much loose paint as possible. Sand rough surfaces. In some cases, it is best to remove all the paint down to the bare surface to avoid the unevenness that results with the removal of many layers of paint in some areas and none in others.

3. MILDEW
This fungus grows in almost any climate; however, mildew is most active where humidity is high and temperatures are warm. Thick shrubbery close to the house blocks out sun and allows dampness to create a mildew-friendly environment. To be certain you are treating mildew and not dirt, soak a small cloth in household bleach and dab it on the surface without wiping. If it's mildew, the spots will bleach out in a few minutes; if it is dirt, it will be unaffected by the bleach.

SOLUTION
Mildew spores must be removed completely or they will grow through the new paint. Remove using a solution of 1-cup powerdered detergent (do not substitute ammonia-containing detergents), 1 quart 5% sodium hypochlorite (household bleach) in 3 quarts of warm water. Spray the solution onto the surface and leave it for five minutes. Thoroughly hose surface with clean water. Repeat if necessary. The surface can also be power washed.