Why Huntsville foundations move
The Geological Survey of Alabama says many areas of the state, particularly north Alabama, are underlain by carbonate rocks such as limestone that dissolve and form caves and sinkholes. It lists sinkhole triggers including a drop in the water table from drought or nearby well pumping, heavy construction or weight at the surface, drainage problems and excessive rainfall. Alabama's caves lie in three main regions, one of them the Tennessee River Valley. Add about 40 freeze-thaw cycles a year at the Huntsville/Madison station, and foundations here need watching.
Step 1: Document
- Photograph each crack with something for scale.
- Mark crack ends with a pencil and date.
- Note sticking doors, gaps at trim and sloping floors.
- Recheck monthly.
Step 2: Fix drainage
Drainage problems are on the Geological Survey's list of sinkhole triggers. Make sure gutters are clean, downspouts discharge well away from the house, and soil slopes away from the foundation. Look for plumbing leaks.
Step 3: Watch for sinkhole signs
A sudden depression, a hole near a downspout or drain line, or a slab section that drops quickly needs prompt professional attention. Keep people away and do not fill it with loose soil or debris.
Step 4: Get an independent evaluation
A structural engineer who does not sell repairs can tell you whether movement is active and what is causing it. On karst ground, ask whether a geotechnical investigation is needed.
Step 5: Compare proposals
Ask each contractor for the cause, the method, the number of piers and their depth or load criteria, permits, warranty and whether it transfers.
Step 6: Licensing
In Alabama, building, remodeling or repairing a residence when the job costs more than $10,000 needs a license from the Home Builders Licensure Board. Many foundation repairs cross that line. Ask for the license and look it up.
Step 7: After the repair
Keep drainage working, recheck marked cracks and fix cosmetic damage once the structure is stable.
Insurance
Many homeowner policies exclude earth movement, and sinkhole coverage varies. Read your policy and ask your agent what applies before you need it.
Records
Keep the engineer's report, contract, permit and warranty together.
Questions to ask an evaluator
Ask whether movement is ongoing or historic, whether water is the likely driver, and whether the site warrants a geotechnical study. Ask what monitoring they recommend over the next year and which signs would mean the plan should change.