A foundation repair contractor
Can look at the problem and propose a repair. They sell the repair, so ask what else could explain what you see.
A Sunken Garage or Basement Slab
This guide does not diagnose your foundation. It helps you decide who to call and what to ask.
Garage and basement floor slabs usually sit on the ground inside the foundation walls. A slab can crack or sink on its own without the foundation walls moving.
Repairs range from lifting or levelling the slab to replacing it. If the walls or the house above are also showing changes, ask for a wider assessment first.
Get it looked at soon if
- The slab keeps sinking or the gap at the wall keeps growing.
- Foundation walls near the slab are cracking or moving too.
- A post or column sitting on the slab has moved.
If you think there is an immediate safety risk, leave the area and contact your local emergency services.
Who can assess it
A structural engineer
Independent of any contractor. Can assess whether there is a structural problem and write a repair scope that contractors then price.
A home inspector
Looks at the whole house and points out what needs a closer look. A general inspection is not a structural assessment.
Services that may come up
Questions to ask every contractor
- Is this only the slab, or is anything under or around it involved?
- Do you lift the existing slab or replace it? Why?
- Will an engineer be involved? Who hires them?
- Who applies for any permit and books inspections?
- What is included, and what would cost extra if you find more damage?
- What does the warranty cover, for how long, and does it transfer to a new owner?
What to record
- Take dated photos from the same spot, with a tape measure or coin for scale.
- Mark the ends of any crack with a pencil and the date, so you can see if it grows.
- Note when it happens: after rain, during snowmelt, or all the time.
- Keep every estimate, report and invoice in one folder.
Slow down if you hear
- Pressure to sign today or lose a price.
- A large deposit before any work or materials arrive.
- A scope that does not say what is included.
- Claims of a grant or rebate you cannot confirm yourself.