Niche Adaptive
Subfloor Leveling: Grinding, Patching or a Pour
July 1, 2026 8 min read By Fort Worth Flooring Co
Subfloor levelling is the line item that makes cheap quotes cheap, because leaving it out is invisible until the floor is down. It is also the line item people most often assume is padding. Here is what it actually is.
What you are correcting, and to what standard
Flatness is not the same as level.
Level means horizontal. Almost no floor in a house that has been standing for decades is perfectly level, and it very rarely matters.
Flatness means free of local deviation — no dips, humps or waves within a given distance. This is what flooring cares about, and it is what every manufacturer specifies.
The tolerance is the flooring product’s, not a general standard:
- Most floating and resilient floors: about three sixteenths of an inch over ten feet
- Large-format tile: about an eighth of an inch over ten feet
- Wide-plank hardwood: tighter than narrow strip, because a long board bridges a dip
You can measure this yourself. Lay a ten foot straightedge across the floor in several directions, including diagonally, and measure the biggest gap underneath it. Then compare against the tolerance for whatever you intend to install.
Why it matters more here than in a lot of places
Fort Worth sits on a geological boundary and it changes how much of this work a house needs.
West and north of the Trinity — Benbrook, Aledo, Saginaw, White Settlement — the Fort Worth Prairie is shallow soil over Goodland and Walnut limestone. Slabs move very little. Preparation is frequently a morning of grinding.
East and south — Arlington, Mansfield, Crowley, Burleson — Eagle Ford and Woodbine clays are strongly expansive. The same age of house on that ground can need a full levelling pour.
Neither is knowable from an address. And flatness is a present-tense measurement: a slab that was flat when the house went up in 1998 frequently is not now, so the builder’s original specification is not evidence about today.
The three interventions
Grinding. Diamond grinding takes high spots down. Fast, dust-contained, and by far the cheapest option. Typical market range around $1 to $4 per square foot.
This is the answer when the floor has localised humps, a slab crack that has developed a lip, or adhesive residue that needs removing along with a small amount of surface.
Patching. Filling localised low spots with a trowel-applied compound, feathered into the surrounding surface. Usually done alongside grinding rather than instead of it.
A self-levelling pour. A flowable cementitious underlayment poured across an area and allowed to find its own level. Typical range $2 to $8 per square foot, and the spread is almost entirely depth — a quarter inch skim and a one and a half inch pour are genuinely different jobs in material, labour and cure time.
This is the answer when the deviation is too broad or too deep for grinding, or when the floor dishes gradually across a large open plan.
What a pour is not
A self-levelling underlayment corrects a surface. It lifts nothing, it stabilises nothing, and it has no structural function whatsoever.
If a slab is moving differentially — settling unevenly rather than simply sitting unevenly — pouring over it produces a flat floor above a moving substrate, and the movement comes back through. That is an engineer’s question, and a flooring contractor who offers to pour over it without raising the distinction is not doing you a favour.
Telling the two apart is part of the assessment. Signs worth mentioning to whoever quotes: doors that have started sticking, cracks in drywall above door frames, and gaps opening between skirting and floor in one part of the house only.
Cure time is schedule, not labour
A pour has to reach both its strength and its moisture specification before anything goes over it. Deeper pours take longer.
This is a real gap in the programme rather than a few hours, and it is worth knowing at the quoting stage because it affects when you get your rooms back. Installing over an underlayment that has not reached its stated moisture level is one of the quieter ways to fail a floor from below.
Wood subfloors
Everything above is about slabs. Over joists, the equivalent work is re-decking, sistering joists, adding blocking, or laying a plywood overlay.
Deflection matters here as much as flatness. It is commonly held to L/360 for most floors and L/720 under stone or large-format tile — a tile floor over a springy span will crack regardless of how well it was set, and no amount of levelling compound addresses that.
How to read your quotes
Ask each bidder what they measured, with what, and what they intend to do about it. A contractor who has not put a straightedge on the floor has priced the material rather than the job.
And be equally suspicious in the other direction. If someone has quoted a substantial pour on a Benbrook or Aledo house sitting on prairie limestone, ask to see the survey that justifies it.
The ranges in one table
Everything above, gathered in one place. These are typical North Texas market ranges rather than our quote.
Refinishing, repair and preparation
| Item | Typical range |
|---|---|
| Sand and refinish hardwood — 3 coats Species, how many previous sandings the boards have left in them | $3 to $6 per sq ft |
| Screen and recoat — no sanding Only worth it above bare wood; winter heating also opens gaps a recoat cannot fill | $1 to $3 per sq ft |
| Dustless sanding surcharge Containment matters more in an occupied historic home than an empty one | Usually folded into the sq ft rate |
| Board replacement — matched and woven in Matching a 1920s longleaf pine board is the expensive part, not the labour | $100 to $400 per board |
| Water damage repair — after a burst supply line How long the water sat, and whether the subfloor delaminated | $400 to $1,800 per room |
| Subfloor repair or replacement Joist condition in a pier-and-beam house is only knowable once it is open | $3 to $9 per sq ft |
| Slab grinding and flatness correction How far out of tolerance the slab reads against the material's spec | $1 to $4 per sq ft |
| Self-levelling underlayment pour Depth. A 1/4 inch skim and a 1.5 inch pour are not the same job | $2 to $8 per sq ft |
Typical North Texas market ranges, gathered from published contractor pricing. Not a quote.