An important decision that must be made early in the planning stage for any home or building is whether to build on a concrete slab or to install a full foundation.
Though they are both technically foundations, each of which can suffer from its own distinct foundation problems, there are pros and cons to each type to be aware of before building.
Concrete Slabs
Concrete slabs are just that; foundations made of a solid, poured slab of concrete on which the structure being built is supported.
There is no space between the building and the ground as the structure sits directly on the slab.
- Pros - Concrete slabs are faster, easier, and less expensive to build, more energy-efficient for keeping the building heated and cooled, require no stairways for entering the building, reduce infestations of rodents under the building, and are well suited for building on heavier soils that can hold more water.
- Cons - Since the building sits directly on the slab and close to the ground, foundation problems are more challenging to deal with and termite infestations are more likely.
Elevated Foundations
Elevated foundations are those constructed as a perimeter around the base of the structure and built up a few feet or more to hold the structure above the ground surface.
Crawlspace and basement foundations are the two examples of elevated foundations, which also have their own positive and negative points.
- Pros - Crawlspace and basement foundations provide additional usable space under the main structure depending on how tall they are, reduce the ability of termites to enter the structure as the floors are raised on a perimeter of concrete and block or brick, and can be used on sloped lots.
- Cons - Elevated foundations are more time-consuming and expensive to build, especially basements, which are usually at least 8 feet high, are not advisable in areas where the soil has a low water table and retains water as foundation problems like leaking and bowed walls can happen, and can increase the cost to heat and cool the building.
Overall, the biggest factor in deciding which type of foundation to use for a particular project must start with determining the soil type and water table, as this will tell you whether a slab or elevated foundation is more suited to the application while avoiding foundation problems.
Beyond that, it is just a matter of balancing the pros and cons and choosing the one that is most desirable.