Let’s get the technicalities out of the way. There are more than two types of foundations. We are aware of this. These two broad categories cover most homes where we repair foundations in the Southeastern United States.
This is the newer category. However, they are growing in their use each year. They appear to be on track to become the majority of new homes built in our region.
A slab foundation is one where they build the house on a large concrete slab. Nothing is accessible under this concrete layer. Some plumbing and electrical may be in or under the concrete. But, the whole house sits on top of the concrete slab. Slab homes need a flat spot to pour the concrete, and then the house starts from there. The slabs are often reinforced with rebar, at least around load points. The concrete is thicker or “turned down” around the edges and under load-bearing walls.
Early wooden homes were constructed on masonry piers with wooden framing above them. These early spaces under the houses were kept open. Once we started poking lots of holes in the floors for plumbing, duct work, and electrical wires sealing these spaces became more critical. A crawlspace is an unfinished area under a house below the floor system and above the dirt. They tend to be shorter, and crawling is the only way to get around. Hence, their name.
The current building code requires 18″ between the bottom of the flooring system and the dirt. Yet, much shorter ones are not uncommon in older homes. We have seen them as tall as 16 feet on the side of steep mountains.
If you can get under the house, and there is no basement (that’s a third category that is more common in the north), you likely have a crawlspace. For our Northern transplants to the Southeast, think of the crawlspace as a short, dirty basement.
In a later post, we’ll discuss the pros and cons of each foundation category. We will also look at some common problems we see with each type.
One last thing before we move on. We always get asked, “What’s better, a crawlspace or a slab?” Our answer is there is not best; both have strong and weak points. A well-built foundation of either type is excellent, and a poorly built one will cause many problems.