By: Barry Stone
Dear Barry,
My house is about 12 years old, and I'm having problems with the patio concrete. The surface becomes white and powdery, and the top layer of the cement peels off. What could be causing this? -- Florence
Dear Florence,
The powdery substance on the concrete is called efflorescence. It consists of mineral salts from the soil or from the concrete itself and is the result of slow moisture seepage through the pavement. Efflorescence is common and generally not indicative of a significant problem, unless it occurs inside the dwelling.
Peeling of the concrete finish is not a common condition and may indicate that the original concrete mix was faulty or that it was poured during freezing weather. If this condition is only occurring at the pavement, not in the house, it is likely to be a minor defect.
At this point, your primary concern is to determine whether these conditions are affecting the dwelling. If your home is built on a slab foundation, you can have the interior checked by rolling back the carpet. If the building is on a raised foundation, the subarea should be checked for moisture and ventilation. The best way to do this is to hire a qualified home inspector. Check with a few real estate offices in your area to determine who is experienced and thorough in this field.
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