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Concrete sealing and coatings
You want to protect concrete, or you want a garage floor that does not look like a garage floor.
Sealers and coatings sit on or just inside the surface of concrete. Sealers are thin and largely about protection: reducing how much water and salt the concrete absorbs. Coatings are thicker film-forming systems — epoxy, polyaspartic, polyurea — that are as much about appearance and cleanability as protection. Both need something sound to bond to, which is why a surface that powders under traffic has to be resolved before either is worth buying.
Both are genuinely useful on the right slab. Neither is structural, and neither fixes anything that has gone wrong below the surface. Whether a sealer is even the right response depends on what the surface is doing, which is the question concrete pitting works through.
What sealing is for
Concrete is porous. Water gets into it, and in climates where that water freezes, it expands. Repeated cycles of that are a principal driver of surface scaling and spalling. Sealers reduce absorption, and in freeze-prone areas that is a real benefit on exterior flatwork.
Penetrating sealers soak in and change how the concrete absorbs water while leaving the surface looking largely unchanged. Film-forming sealers leave a layer on top, often with a sheen, and need reapplication on a cycle. Which suits you depends on appearance preference, slip considerations and how much maintenance you want.
Garage floor coatings
Epoxy and polyaspartic garage floor systems are the most common residential coating. Done properly they resist hot tyre pickup, tolerate automotive fluids, clean easily and last for years.
Done improperly they peel. Almost every failed garage floor coating failed at the bond, and almost every bond failure traces to preparation: coating over a sealed or contaminated slab, skipping mechanical profiling, or applying over a slab with a moisture problem. The single most useful question about a coating quote is what happens to the concrete before the coating arrives.
- Mechanical profiling — grinding or shot blasting — rather than acid etching alone.
- Moisture testing on slabs where vapour drive is plausible, particularly slabs with no vapour barrier beneath.
- Repair of cracks and spalls before coating, not after.
- A realistic cure schedule before vehicles return.
When a coating is the wrong answer
A coating over a slab that is spalling because of freeze–thaw damage does not stop the damage; it covers a surface that is still coming apart underneath it, and it comes off with that surface.
A coating over a slab with a moisture problem fails as vapour pushes through from below. A coating over a moving crack cracks. A coating on a slab that is settling is a nicely finished settled slab.
When sealing or coating makes sense
- New or sound concrete you want to protect before damage starts.
- Exterior flatwork in a climate with regular freeze–thaw cycling and de-icing salt exposure.
- A garage floor that is structurally sound and reasonably flat.
- Surfaces where cleanability and appearance are the goal.
When to fix something else first
- Concrete that is actively scaling, spalling or delaminating.
- Slabs with moisture coming through from below and no vapour barrier.
- Any slab that has settled or is settling.
- Concrete with active, moving cracks.
Alternatives worth pricing
- Resurfacing, where the surface is too far gone to simply seal.
- Repair of the underlying issue first, then sealing.
- Doing nothing, where the concrete is sound and unexposed — not every slab needs a sealer.
What moves the price
We do not publish national dollar figures. A single average applied across every site, method and market gives you a confident-looking benchmark that is wrong for your job in an unknown direction. What does transfer between jobs is the structure of the price:
- Square footage and system specified.
- Preparation required, which dominates on a contaminated or previously sealed slab.
- Repairs needed before coating.
- Number of coats and any decorative flake or colour.
- Whether the space has to be emptied and for how long.
Local quotes decide actual pricing. If you want to compare two of them properly, the quote comparison guide covers how.
What to ask a contractor
- How will the slab be prepared, mechanically?
- Have you tested for moisture, and what did you find?
- What product, what thickness, how many coats?
- What happens at the existing cracks and joints?
- How long before vehicles or furniture return?
- What does the warranty exclude — does it exclude peeling from moisture, or from bond failure?
- How often will this need reapplying, and what does that cost?
How we know what this page says
Each of these is something this page says. What follows is why we say it, what we had to assume, and what would change our mind — so you can weigh it rather than take it on trust. How we grade what we publish.
Sealing is a preventive measure rather than a correction of existing damage.
Established practice This is how the work is normally done, and it is not seriously contested among people who do it. It usually reflects material behaviour or long-standing method rather than opinion.
Evidence considered
- A sealer works by limiting what gets into the concrete, which is a preventive mechanism.
- Applying it over a surface that is already deteriorating does not reverse the deterioration.
- Its preventive role is not contested.
Still to establish
- Finish and sealer history — partly, on your own
- Whether damage is surface or full depth — partly, on your own
- Freeze exposure — partly, on your own
Why we say this, and when it may not apply
Sealer is inexpensive and widely sold, and it is regularly proposed for surfaces where the deterioration has already happened. Knowing which side of that line you are on determines whether the money does anything.
What we had to assume
- That the surface is sound enough for the sealer to do its job.
- That the exposure the sealer protects against is actually the exposure present.
When this may not apply
- On sound new concrete, sealing is straightforwardly worth considering on its own terms.
- Where the surface is already deteriorating, sealing is not the first question.
What would change it
- Establishing whether the surface is currently sound or already breaking down.
- What has previously been applied, which affects what will adhere.
- How much freeze exposure and de-icing that surface actually sees.
Established practice does not mean this: It does not mean the practice is right for your property, that any particular contractor follows it, or that following it guarantees an outcome. Established practice describes what is normal, not what will happen at your address.
Common questions
How often should exterior concrete be sealed?
It depends on the product, the exposure and the traffic, and the manufacturer's interval for the specific product is the figure that matters. Treat any single universal number as marketing. Ask the contractor for the product data sheet.
Why did my last garage floor coating peel?
Most often preparation or moisture. A coating applied over a slab that was not mechanically profiled, or was still sealed from a previous treatment, or has vapour moving up through it, will release regardless of how good the product was. That is why the preparation questions matter more than the brand.
Will sealing stop my concrete from cracking?
No. Sealing reduces water absorption, which helps with surface deterioration in freezing climates. Cracking is driven by shrinkage, loading, movement and jointing — none of which a sealer touches.
Work it out, or judge the quote
Related guides
Resurfacing and overlays
A new wearing surface over sound concrete — and the movement problems it cannot fix.
Read more →Garage floors
Interior slab, exterior abuse — coatings, cracks and the threshold step.
Read more →Spalling concrete
Surface breaking away in chunks, often with aggregate showing — usually water, freezing and salt.
Read more →Flaking and scaling
Thin layers lifting off the surface — a finishing, curing and freeze–thaw story.
Read more →Patios
Lightly loaded, highly visible — where appearance often drives the decision.
Read more →