Concrete Leveling in Seattle
Concrete leveling, also called slab lifting, raises an outdoor slab that has sunk by pumping mudjacking slurry or polyurethane foam into the void beneath it; it doesn't resurface an interior floor or grind concrete away. Settled concrete slabs are common in Seattle: driveways that have dropped toward the garage, patio sections that hold standing water, walkway panels with a raised edge at the joint. Seattle’s clay-heavy soils and high annual rainfall (37–50 inches) accelerate the void formation beneath slabs that causes settling. Concrete leveling lifts the existing slab back into position — without demolition, without new concrete curing time, and at a fraction of replacement cost. Typical prices are in concrete leveling cost in Seattle.
Free on-site estimate · Call (206) 552-9998 or request a quote
Leveling an interior basement or garage floor for new flooring? See concrete floor leveling.
Why concrete settles in Seattle
The glacial lake sediments and marine clay soils common across Seattle, Bellevue, and Renton shrink and expand significantly with moisture changes. Every wet season saturates the subbase; every dry summer dries it out. That cycle creates voids beneath slabs over years. Poor subbase compaction during original installation accelerates the process. Tree roots, utility-line trenches that weren’t properly backfilled, and steep lots with active surface runoff are other common causes in this region.
Mudjacking (slabjacking)
A slurry of portland cement, water, and soil is injected under the slab through 1.5–2 inch holes drilled at intervals. Hydraulic pressure fills the void and lifts the slab. Holes are patched with matching concrete after lifting. Mudjacking is the most economical option for large-area settled slabs — driveways, patio fields, garage floors — and the cured fill material is durable and stable. Cost: $3–$8/sqft depending on number of injection points.
Polyurethane foam lifting
Two-part expanding polyurethane foam is injected through smaller holes (5/8 inch) and cures in minutes rather than days. It is lighter than mudjacking material, which reduces additional load on a subbase that has already shown weakness. Foam is the right choice when quick turnaround is critical or when the slab is at risk from the weight of mudjacking slurry. Cost: $5–$12/sqft — more expensive than mudjacking but often faster and less disruptive.
Mudjacking vs. polyurethane foam at a glance
| Mudjacking | Polyurethane foam | |
|---|---|---|
| Injection holes | 1.5–2 inches | About 5/8 inch |
| Fill material | Cement, soil and water slurry | Two-part expanding foam |
| Weight added to the soil | Heavy | Light |
| Back in use | Same day after patching | Usually within 15–30 minutes |
| Typical cost | $3–$8/sqft | $5–$12/sqft |
| Best for | Large settled areas on firm soil, tight budgets | Weak or wet subgrade, quick turnaround, smaller visible patches |
Neither method fixes the reason the soil washed out. The downspout, gutter overflow or broken drain line that created the void has to be corrected at the same visit, or the slab will drop again. For full price ranges by surface and slab size, see mudjacking vs. foam cost in Seattle.
Choosing a concrete leveling contractor
Concrete leveling companies range from foam-only franchises to general concrete crews, and the quotes can look very different for the same slab. Questions worth asking before you hire:
- Which method do you recommend for this slab, and why that one rather than the other?
- How many holes, where will they go, and how will the patches match the existing concrete?
- How do you find the extent of the void, and how do you avoid over-lifting or cracking the slab?
- What is causing the settlement, and is fixing it (downspouts, drainage, a leaking line) part of the quote?
- Will the joints and the gap between the slab and the house be sealed afterward to keep water out of the base?
- What happens if the slab cracks during the lift, or settles again?
A contractor who also pours new concrete can tell you honestly when a slab is too broken to lift; see leveling cost vs. replacement for that decision.
Not the same as interior floor leveling
Slab lifting raises concrete that has dropped. It does not flatten a basement or garage floor that is sound but wavy. That job uses self-leveling underlayment or grinding, covered on our interior floor leveling and concrete grinding pages.
Leveling vs. replacement — how to decide
Level it when the slab is structurally intact, cracks are narrow and stable, and the settling is caused by a void that can be filled. Replace it when the slab is crumbling, heavily cracked with visible displacement between panels, or so thin it will fracture during lifting. As a general rule, leveling costs 25–50% of what a new pour would cost for the same area.
Typical leveling projects in Seattle
Driveway panels that have settled toward the street or garage apron. Patio slabs creating trip hazards at control joints. Sidewalk sections heaved by tree roots (root pruning first, then leveling or replacement). Garage slabs and garage aprons that have dropped as a unit. Stoops and landings that have pulled away from the house.
Frequently asked questions
How much does concrete leveling cost in Seattle?
Mudjacking runs $3–$8/sqft; polyurethane foam lifting runs $5–$12/sqft. A typical settled driveway panel (50 sqft) costs $150–$400 for mudjacking or $250–$600 for foam lifting, including injection, hole patching, and cleanup.
How long does lifted concrete last?
A well-executed lift on stable, well-drained soil typically lasts 5–15 years. If the underlying drainage issue is not addressed — a downspout discharging near the slab, for example — the void reforms faster.
Is leveling cheaper than replacement?
Usually 25–50% of replacement cost. But if the slab is thin, repeatedly settling, or severely cracked with active movement, replacement often delivers better long-term value. We give an honest recommendation at the estimate.
Can all concrete be leveled?
No. Slabs thinner than 3 inches, heavily fractured slabs with multiple displaced sections, or situations where the soil is still actively eroding are not good candidates. We assess the slab condition before recommending a method.
How long does concrete leveling take?
Most jobs are complete in a few hours. Mudjacking holes can be walked on the same day after patching. Foam-lifted slabs are usable within 15–30 minutes of completion.
What should I ask a concrete leveling company before hiring?
Ask which method they recommend and why, how many holes they will drill and how the patches will look, what caused the settling and whether fixing it is included, whether joints will be sealed afterward, and what happens if the slab cracks or settles again.
Should the joints be sealed after a slab is lifted?
Yes. Sealing control joints and the gap between the slab and the house with a flexible sealant keeps rainwater from running into the base, which is how most voids form in the first place.
Service areas
We handle slab lifting and leveling across King, Snohomish, Pierce, and Thurston counties, including in Kent, Auburn, Sumner, Puyallup, and Enumclaw. See all service areas.
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