Healthy Home Basics - Foundations, Decks, and Garages

22. What is the healthiest type of foundation?

There are four basic foundation types: concrete slab, crawl space, basement, and pier. In general, pier foundations are the easiest to build in a healthy manner because they lift a house up off the ground. When a house is well separated from the soil, it’s more difficult for radon , subterranean termites, and ground moisture to get into the living space. Pier foundations are often used on hillside lots or in hot/humid climates.

Actually, any foundation can be healthy—if constructed and maintained carefully. You need to be concerned with moisture (both liquid water and relative humidity) which can lead to mold or rot, radon (a cause of lung cancer), subterranean-termite control (toxic chemicals should be avoided whenever possible), energy savings (to minimize heating/cooling expenses, and reduce the potential for condensation), and selecting materials that are inherently healthy.

23. Don’t concrete slab foundations tend to be damp and moldy?

No, not if they’re constructed correctly. We’ve built healthy concrete slabs several times and like them because they can easily be surfaced with a covering of low-tox ceramic tile. If you’re on a very tight budget, a colored concrete slab decorated with natural-fiber area rugs can be an attractive choice. And, it can still be covered with tile later, when you have some extra cash.

Actually, we’ve found that very few sensitive people react to concrete. This is especially true if no chemicals (usually called admixtures) are used in the basic concrete mix. You should also avoid chemical curing compounds—misting water on a slab will keep it moist so it will cure slowly and naturally.

24. I want to use concrete foundation walls for a basement or crawl space. Is there a healthy form-release agent and dampproofing material?

Contractors usually coat wood or metal foundation forms with a petroleum-based oil so they won’t stick to the concrete. However, the oil often contaminates the concrete enough to bother sensitive people. Although it costs a little more, some people have had success by simply using a vegetable cooking oil instead. But if the forms are already saturated with petroleum-based oil from past jobs, a better solution is to first line them with polyethylene plastic sheeting. That way, after they've been filled with concrete, which has then cured, and the forms removed, the plastic can be easily peeled off.

Dampproofing coatings are often black, odorous, tar-like compounds. Because they’re on the outside of the foundation wall, they aren’t directly exposed to the living space , so they usually don’t often affect the indoor air quality. But in rare instances, they can, so sens...