When a Basement Floor Needs Replacing
A basement floor can crack, heave, sink or stay damp because it was poured thin, on poor soil, without a vapour barrier, or because water has been working under it for years. Patching works for small cracks; when the slab is broken up, uneven or damp across the room, concrete slab replacement is the lasting fix.
We remove the old floor, fix what is underneath — compacted gravel base, vapour barrier, optional insulation and drainage — and pour a new level slab, ready for finishing.
For floors lowered to gain height, see basement lowering; for structural foundation work, see foundation repair.
What Goes Under a New Basement Floor
Base
A solid base stops settling and cracking.
- Old slab broken out and removed
- Soil levelled and compacted
- Clear gravel base
- Drain lines checked while open
Moisture control
Keeps the new floor dry.
- Polyethylene vapour barrier
- Rigid insulation option for warmer floors
- Interior drainage tie-in if water rises
- Sump pit if needed
Concrete
Level, finished and ready for flooring.
- New concrete slab poured and levelled
- Floor drain set to slope
- Control joints to manage cracking
- Trowelled finish
Repair, Resurface or Replace?
| Floor condition | Usual fix | Typical price |
|---|---|---|
| A few cracks, otherwise sound | Floor crack repair | $300 – $1,200 per crack |
| Rough or worn surface | Resurfacing | $4 – $10 per sq ft |
| Uneven but solid | Concrete leveling | $5 – $15 per sq ft |
| Broken, sunken or damp throughout | Full slab replacement | Quoted by area |
| Floor too low for use | Lowering — see basement lowering | Per linear foot |
Approximate 2026 Toronto prices, not a quote.
Signs Your Basement Slab Needs Replacement
Wide or spreading cracks
Cracks that grow or have edges at different heights.
Sinking or heaving
Low spots, humps or a tilted floor.
Damp floor
Moisture coming up through the slab.
Water at cracks
Groundwater pushing through the floor.
Broken or crumbling concrete
Thin, old or poorly mixed slab.
Renovation planned
Best time to fix the floor is before finishing.
How We Replace a Basement Slab
Assessment
Floor condition, moisture, drains and the cause of damage.
Written plan
Repair or replacement, base, vapour barrier, insulation and price.
Remove the old slab
Broken out and hauled away.
Prepare the base
Soil compacted, gravel placed, drains checked.
Moisture layers
Vapour barrier and optional insulation.
Pour & finish
New concrete placed, levelled and finished.
Related Services
Concrete Floor Installation Alongside Other Basement Work
The floor is open only once — the best time to fix everything under it.
Interior weeping tile
Perimeter drain and sump pit set before the new pour.
- Stops water under the slab
- Ties into a sump pump
- Cheapest time to add it
Plumbing rough-ins
Drains for a future bathroom, laundry or kitchen.
- Set at the right slope
- Inspected before pouring
- Backwater valve if needed
Insulation and heat
Rigid insulation and in-floor heat sit under the concrete.
- Warmer floor
- Less condensation
- Plan height before you pour
Vapour and radon control
Poly vapour barrier and sealed penetrations.
- Keeps ground moisture out
- Radon rough-in pipe option
- Required for finished spaces
What Affects Concrete Slab Replacement Cost
Every basement is quoted after an inspection. These are the things that move the price.
| Factor | Why it matters |
|---|---|
| Floor area and thickness | More concrete, more removal and more labour |
| Access | Concrete removed and placed by hand through windows or stairs costs more than with a chute or pump |
| What goes under it | Weeping tile, plumbing, insulation and radon pipe add scope |
| Structural slab replacement | Slabs that carry posts or walls may need engineered footings |
| Finish | Smooth trowel finish for flooring vs a basic broom finish |
Permits and Building Code for a New Basement Floor
When a permit is needed
Lowering the floor, adding plumbing or changing structure needs a building permit; a like-for-like slab replacement often does not.
Under the slab
Code-compliant floors have a granular base, a vapour barrier and concrete of the required strength and thickness.
Plumbing inspection
New under-slab drains must be inspected before the concrete goes in.
Secondary suites
Basement apartments have extra rules for ceiling height and fire separation — plan the floor height around them.
What to Ask Concrete Floor Contractors
What goes under the slab?
A good concrete flooring contractor specifies the base, vapour barrier and insulation, not just the concrete.
How is the floor sloped?
Floors near drains should slope slightly toward them; the rest should be flat enough for flooring.
How is dust controlled?
Breaking concrete indoors makes dust — ask about plastic barriers and air scrubbers.
How long before I can use it?
You can walk on new concrete in about a day; flooring usually waits several weeks while it dries.
Basement Slab Questions
When should a basement floor be replaced instead of repaired?
When it is broken up, sinking, heaving or damp across large areas. Isolated cracks can usually be repaired.
How much does basement floor replacement cost?
It depends on the area, removal and what goes under the new slab. Floor crack repair is $300–$1,200 and resurfacing $4–$10 per sq ft; full replacement is quoted by area.
Do you install a vapour barrier?
Yes, a polyethylene vapour barrier goes under the new slab, with insulation as an option.
Can you add drainage under the new floor?
Yes. While the floor is open is the best time to add interior weeping tile and a sump pit.
Do I need a permit?
Usually not for a like-for-like slab replacement; lowering or structural changes need one.
How long does it take?
Most basement slabs are removed and replaced over several days, plus curing time before flooring.
Can I stay in my home during slab replacement?
Usually yes. The basement is off-limits during the work, and we seal off the area to limit dust in the rest of the house.
How long does basement slab replacement take?
Most basements take about one to two weeks from breaking out the old floor to pouring the new one, longer if drainage or plumbing goes in at the same time.
Can you replace only part of the slab?
Yes. Sections around a new drain, a sump pit or a damaged area can be cut out and replaced on their own.
Will a new concrete floor stop dampness?
A new slab with a vapour barrier and a drainage layer stops moisture coming up from the ground. Water coming through walls still needs waterproofing.
Get a Basement Floor Quote
Tell us what the floor looks like. We will check it and quote the repair or replacement.
Call now — Mon–Fri 7 AM – 4 PM(416) 992-5858Office: 58 Six Point Rd, Etobicoke, ON M8Z 2X2
Email: info@leaquida.ca
Licence No.: P94 4418977 (licensed contractor)