Application
Polyurethane foam injection explained
Polyurethane concrete lifting uses a two-part foam pumped through small holes. As the components react they expand, fill voids and — when injected in controlled stages — exert upward pressure on the slab.
Why it settles
- Voids and weak soil beneath slabs
- Settled backfill
- Erosion from water
Often suitable
- Intact slabs needing lift or support
- Void filling where access is limited
Usually not suitable
- Broken or deteriorated concrete
- Heaved slabs
- Situations where the underlying soil problem is ongoing and unaddressed
Risks, drainage and other considerations
- Different foam densities are used for lifting versus void filling — ask which product is proposed and why
- Product data sheets list properties; ask for them
- Cure and return-to-use times depend on product, temperature and site
Lift or replace?
Lifting keeps the existing concrete, so it makes sense only when that concrete is worth keeping. If it is broken up, deteriorated or heaved, replacement is usually the better route. See lifting vs replacement and what affects cost.
Check before you ask
Use the free slab self-check, the area calculator or the photo checklist, then send the summary with your request. See also the visual guides.
Questions
Is the foam waterproof?
Closed-cell polyurethane foams used for lifting are generally water-resistant. Ask for the manufacturer’s data sheet for the specific product.
Request an assessment
Other applications
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