These two types of foundation are common in different states. Their structural integrity depends on a number of factors including the home’s age, the ground on which it stands, the general area, and recent severe weather. Let us look at each type.
1. Pier and Beam (aka Raised Foundation)
This foundation is built on a series of concrete posts driven vertically into the ground (piers.) The beams are horizontal posts lying across the piers, and on which the property is built. The space between the ground and the floor is the crawlspace. Crawlspaces have advantages and disadvantages.
- The space under the floor is where the electrical cables, plumbing lines, and underfloor HVAC ducts are found.
- This makes inspections and repairs easier just because an inspector or contractor can easily get in and do their job.
- Vermin, insects, and burrowing creatures can make the crawlspace their home.
- Dust and spores often accumulate resulting in allergic reactions.
- Rainwater can seep in encouraging mold and can make repair work difficult if the ground is sodden or flooded.
2. Slab Foundation
Builders often choose slab because it is easier and cheaper. There are two types of slab:
- Basic flat concrete.
- Wafflemat. This has a flat top and the underside looks like a waffle. The spaces in the “waffle” allow for soil expansion and contraction, so cracking in walls should be less common. The criss-cross ridges deliver stability. If possible, an investor should know how far apart the criss-crossing is. The builder will know, if you can make contact, or get a copy of the blueprint. If the spaces are too wide there is less stability.
- A well-built home by a reputable builder should be structurally sound.
- It is a lower-cost construction system, so the home may cost less to buy.
- If the criss-cross is too wide, the foundation will be less stable and may encourage cracking. The soil-type and general weather conditions will also affect stability.
- Plumbing lines are underneath the floor and encased in concrete. Any repairs, therefore, mean holes have to be drilled into the foundation before repairs can be made.
The wise investor will research the foundation type to see what it is. A long-term resident may know what damage there has been over the years, as will public records if permits were needed to correct a failure. It is impossible to estimate potential repair costs but the better the original work, the higher quality the materials used, and the ground on which the property stands, the general location and recent weather phenomena (flooding, etc.) will all affect likely future repair costs.
Investors should hire a well-qualified inspector who knows the locale to assess structural issues, and a WDO (pest) inspector, particularly to look at the crawlspace.