Window Wells, Foundation Walls & Walkouts: Outdoor Concrete Wall Finishes Compared
Short answer: for outdoor concrete walls with soil behind them, grind them smooth, fill the holes, and finish with a clear water repellent plus a mineral concrete glaze. It keeps the concrete look, evens out the colour, and breathes, so it doesn't crack and peel like parging, paint or epoxy. Below is every option side by side, so you can pick what fits your house.
Why outdoor walls are different
A window well or foundation wall has wet soil on one side and Ontario weather on the other. Moisture moves through the concrete toward the open side, water and road salt soak in, and it freezes and thaws dozens of times a winter. Any finish that forms a sealed layer on top traps that moisture, and that's why parging cracks, paint peels and floor coatings blister on these walls.
The finishes that last are the ones that soak in and let the wall breathe. That's the thread through everything below.
All the options at a glance
| Finish | Looks | Outdoors, soil behind | Best for |
|---|---|---|---|
| Ground smooth + mineral glaze | Real concrete, smooth, one even grey (or a tint you choose) | Very good. Breathes, so it can't blister or peel; mineral colour doesn't fade | Window wells, foundation walls, stairwell walls |
| Ground smooth + clear water repellent | Real concrete, smooth. Patch spots and colour differences stay visible | Very good. Nothing on the surface to peel | When the concrete colour is already even, or the budget is tight |
| Parging | Smeared cement, often blotchy and uneven | Poor on walls with wet soil behind: cracks and falls off after a few winters | A quick cover-up, not a finish |
| Microcement skim coat | Plaster-smooth, soft trowel marks, no concrete texture | Risky. Can crack or pop off when water gets behind it | Covered or indoor walls |
| Epoxy or polyaspartic flake | Speckled, like a garage floor | On soil-backed walls the film traps moisture and can blister and peel | The stairwell landing and treads (with grip), not the walls |
| Quartz (coloured sand in resin) | Sandy, textured, very grippy | Same film problem as flake; the sand doesn't stay on a vertical wall | Outdoor steps and landings where grip matters |
| Decorative cement overlay (Jewelstone-type) | Faux stone or tile pattern, textured | Common on GTA porches and walkouts; needs resealing every few years | Steps and porches where you want stone instead of concrete |
Ground smooth + mineral glaze
We grind off the form lines and fins, fill the tie holes with a grey cement repair mortar, add a clear water repellent, then brush on two coats of a mineral concrete glaze (we use KEIM Concretal-Lasur). The glaze is a see-through stain for concrete: liquid glass plus mineral pigment. It soaks in and reacts with the concrete, so it becomes part of the surface instead of sitting on top of it.
What it fixes is the colour. Patches, pour lines and dark streaks blend into one even tone, while the concrete texture stays. You pick how strong it is on a test patch: thin lets more of the concrete show, thicker covers more.
- Looks
- Real concrete, smooth, one even grey (or a tint you choose)
- Outdoors
- Very good. Breathes, so it can't blister or peel; mineral colour doesn't fade
- Upkeep
- Low. No film to wear through; can be refreshed with another coat
Ground smooth + clear water repellent
Same grinding and patching, then a clear water repellent (a silane or siloxane). It's a clear liquid sprayed or brushed on that soaks a few millimetres into the concrete and makes water bead off. No film, no shine, no colour change, and the concrete still breathes. It slows the water and salt damage that makes outdoor concrete flake.
The catch: it's invisible, so whatever the wall looks like after grinding is what you get. Grey repair patches and pour-to-pour colour changes stay.
- Looks
- Real concrete, smooth. Patch spots and colour differences stay visible
- Outdoors
- Very good. Nothing on the surface to peel
- Upkeep
- Re-apply the repellent every several years
Parging
Parging is a layer of cement mortar troweled over the wall. It hides the rough pour for a while, but it dries patchy, and outdoors in Ontario it often cracks and lets go after a few freeze-thaw winters. Water and salt get behind it and push it off. If you're reading this because your parging is falling apart, that's the usual reason.
- Looks
- Smeared cement, often blotchy and uneven
- Outdoors
- Poor on walls with wet soil behind: cracks and falls off after a few winters
- Upkeep
- Patching and redoing
Microcement skim coat
A thin polymer cement troweled over the wall and sealed. It gives the most uniform, modern surface, but it's a separate layer on top of the concrete. On a wall with soil behind it, moisture and frost work against that bond. We'd only consider it where the wall stays dry. More on it in our microcement guide.
- Looks
- Plaster-smooth, soft trowel marks, no concrete texture
- Outdoors
- Risky. Can crack or pop off when water gets behind it
- Upkeep
- Resealing every few years
Epoxy or polyaspartic flake
Flake is our main floor system: a resin base, coloured chips and a clear polyaspartic top coat. It's a sealed film, which is what you want on a garage floor, and exactly what you don't want on a wall with wet soil behind it: moisture pushes out, gets trapped behind the film and lifts it. On a walkout stair landing or treads it can work, with grip in the top coat, if the slab was poured over a vapour barrier. See our flake floor guide.
- Looks
- Speckled, like a garage floor
- Outdoors
- On soil-backed walls the film traps moisture and can blister and peel
- Upkeep
- Low on a floor; on these walls, repairs
Quartz (coloured sand in resin)
Quartz is coloured sand broadcast into wet resin and locked in with a top coat. It's one of the grippiest floor finishes there is, so it's a real option for walkout steps. On walls the sand falls off before the resin sets, and the resin has the same moisture problem as flake. More in our quartz flooring guide.
- Looks
- Sandy, textured, very grippy
- Outdoors
- Same film problem as flake; the sand doesn't stay on a vertical wall
- Upkeep
- Low on a floor
Decorative cement overlay (Jewelstone-type)
Jewelstone and similar products are acrylic-modified cement overlays, applied in a thin layer and finished to look like stone or tile. They're popular on GTA porches and walkout stairs. It's a different look, not concrete anymore, and it's a layer on top that needs regular resealing. Specialist dealers install these; we don't.
- Looks
- Faux stone or tile pattern, textured
- Outdoors
- Common on GTA porches and walkouts; needs resealing every few years
- Upkeep
- Reseal on a schedule
How we do the recommended finish
- Cover the windows. Grinding dust scratches glass and silicate products etch it, so windows and frames get plastic first.
- Grind. A diamond cup wheel takes off fins and form lines, then resin pads make the face smooth to the touch. Matte, not polished.
- Patch. Tie holes and bug holes get a fine grey cement repair mortar, ground flush once it cures.
- Clean and dry. Form oil and dust come off, and the wall dries fully. We check it with a moisture meter.
- Water repellent. A clear silane goes on until the wall stops soaking it up, including the flat tops.
- Test patch. You pick the glaze strength and shade on a small area.
- Two coats of glaze, 12–24 hours apart, worked corner to corner so there are no lap marks. Then it's kept out of rain and direct sun while it cures.
Timing: new concrete needs at least 28 days. The glaze goes on in dry weather between about 5 and 30 °C, out of direct sun (KEIM's application range), so in Ontario we book these for spring or early fall.
Walkout stairwells: walls and steps
The walls get the same treatment as window wells. The steps are different: they need grip, because they get wet and icy. A broom finish from the pour plus a clear water repellent is the simple, safe choice. If you want colour and texture, quartz or flake with grip in the top coat can work on the treads and landing, as long as the slab was poured over a vapour barrier and the work is done in warm, dry weather.
Building new? Ask your concrete crew for smooth plastic-faced forms and good vibration. Less grinding afterwards means a better finish for less money.
Questions homeowners ask
What's the best finish for concrete window wells?
If you want them to still look like concrete: grind them smooth, fill the tie holes, then a clear water repellent and a mineral concrete glaze. It evens out the colour, and because it soaks in and breathes, it doesn't peel the way paint, epoxy or parging does on walls with soil behind them.
Why does parging fall off foundation walls?
Water from the soil and from rain gets behind it, freezes and expands, and salt adds to it. After a few winters the bond breaks and it cracks or falls off in sheets.
Can you epoxy outdoor concrete walls?
On walls with soil behind them, we don't recommend it. Epoxy and polyaspartic are sealed films; moisture pushing out through the wall gets trapped behind them and can lift them. They work well on floors and on walkout steps poured over a vapour barrier.
What is a clear water repellent for concrete?
A clear silane or siloxane liquid that soaks a few millimetres into the concrete and makes water bead off. It leaves no film, shine or colour, and the concrete can still breathe.
When can new concrete be finished?
Wait at least 28 days after the pour. The glaze and water repellent go on in dry weather between about 5 and 30 °C, out of direct sun, so in Ontario that's usually spring or early fall.
Do I have to do the whole wall?
We start with a test patch on one wall so you can see the colour and strength of the glaze before we do the rest.
Get a price for your walls
Every wall job is quoted after we see it: how many walls, how rough the pour is and how many holes need filling. Send us a few photos and the rough size, and we'll text you back with the options that fit. We also do outdoor concrete coatings and concrete repair.