Why does the wall just above the ground fail first?

The strip of wall in the bottom three feet of a building fails before the rest of it because that is where the salt and the snow sit all winter. Plows and shovels bank it against the wall, it melts, and the salt water soaks into brick, mortar and concrete at exactly the height where nobody looks.

Two things go wrong from there. Water washes down off the pavement, tracks along the wall, and ends up in the parking garage below or inside the building structure. And the wall face itself fades and goes frail, which makes it absorb more moisture, which makes it crack harder on the next freeze. It compounds.

Liquid flashing is the repair for that strip: a coated band that seals the wall from grade up to about three feet.

What is actually failing in the bottom three feet of the wall?

The bottom three feet of a wall fails through salt saturation followed by freeze-thaw cracking. Salt water gets into the pores of the brick and the mortar, and when it freezes it expands and opens micro-cracks. Next thaw, more water gets in. The wall gets progressively more absorbent, so each winter does more damage than the one before.

Brick itself is durable — more durable than concrete. The problem is the mortar between the courses, which is considerably more porous than concrete is. So a brick wall does not fail at the bricks. It fails at the joints, and the bricks come loose and drop out after the mortar around them has gone.

A rule of thumb worth keeping: about one hundred freeze-thaw cycles is equivalent to twenty-five years of wall life.

That number is per elevation, not per building. A wall facing the sun thaws in winter sunlight even on a cold day and refreezes when the sun sets, so it racks up cycles a shaded wall never sees. The shaded elevation freezes in December and stays frozen. Wind adds to it too, both drying the material out and cooling the surface faster.

Which is why you get one wall of a building coming apart while another looks nearly new. On the three City-inspected rental properties we worked through this year, the damage concentrated hard on particular sides — driven by sun, by wind, by where cars drive past, by where the snow gets banked and how much salt that stretch of ground sees. It is almost like a multiple-to-multiple equation you are solving.

The practical part: once you can see it, fixing it now costs a fraction of what it costs later.

How is liquid flashing applied?

Liquid flashing is applied in five steps, and the order matters more than any single material in it.

1. Tape and burnish the top line. Tape goes on at the height the coating will finish, and it gets burnished down hard so nothing bleeds underneath it. That is what gives a clean straight termination instead of a wavy edge that reads as a repair.

2. Chip out everything loose. Any brick or concrete that has let go comes off. There is no point coating over material that is about to fall.

3. Rebuild the surface. Polyforce Plus adhesive, then polymer cement to bring the surface back. Where there is corrosion in the substrate we use Sika MonoTop 122, which handles the corrosion inhibitor and the bonding in one product — and comes in different consistencies depending on whether you are working on a floor, a wall or overhead.

4. Prime the whole area with a waterproofing epoxy primer. All of it, not just the patched parts.

5. Coat it. Two builds, depending on how bad the wall is. Light damage gets Deckhide, a polyurea by Superskin, straight over the primer — decorative finish and protective finish in one pass. Severely deteriorated wall gets a sheet of woven fiberglass laid into the adhesive first, then Deckhide over the top of that.

The fiberglass comes in four-by-ten-foot sheets and gets cut to size and applied as a single sheet rather than pieced together.

This is the same family of thin-patch concrete repair we use elsewhere, applied to a vertical surface with a coating over it.

Why does the coating have to run past the edge of the fiberglass?

The polyurea has to terminate past the edge of the fiberglass, not level with it, or the reinforcement curls and lifts. This is the single detail most likely to be got wrong, and we have seen it fail.

Where there was not enough waterproofing epoxy or Deckhide above the fiberglass edge, the edge starts to curl, it delaminates, and moisture gets in behind the coating — which is the exact failure the coating was installed to prevent. Terminated properly, over a razor-cut straight edge of woven fiberglass, with the Deckhide carried past that edge, we have not seen one let go. It adheres.

Same rule applies at the bottom of the run near the ground. The application finishes with Deckhide or epoxy. It never finishes with exposed fiberglass.

Woven fiberglass or non-woven geotextile — does it matter?

Woven fiberglass is the correct reinforcement for this detail and non-woven geotextile is not, and the reason is thickness.

Woven fiberglass is about the thickness of a sheet of paper, maybe two sheets. Non-woven geotextile is roughly four to five times that. Geotextile is specified by weight per square metre, and the range you do not want here is 150 to 300 grams per square metre. At the light end it behaves like a fleece: hard to lay flat, it smears and curls, and it does not offer much protection because it will not sit still as a sheet. At 300 grams it comes out a couple of millimetres thick, which is thicker than this detail needs by a factor of six or seven.

And that thickness is itself the failure mechanism. A thick non-woven mat absorbs a large volume of coating, which builds a heavy edge, and the heavy edge is what delaminates.

	Woven fiberglass	Non-woven geotextile
Thickness	One to two sheets of paper	Four to five times that
Coating absorbed	Minimal	High
Behaviour during application	Lies flat, holds a cut edge	Smears and curls
Edge behaviour over time	Stays bonded	Prone to delamination

Woven stays thin, takes up very little material, and still gives a surface that is close to impossible to penetrate. It also survives hot salt spray testing, and it stays soft enough that a mechanical knock bridges rather than cracks.

How long does it take, and why does the speed matter?

A liquid flashing run on a mid-size rental building takes about three days start to finish, and the coated wall is back in service within ten hours.

On one of the rental properties this year we ran liquid flashing along roughly fifty per cent of the building perimeter, concentrated where the building runs alongside an above-ground ramp. Runoff was collecting at the bottom of that ramp and doing real damage to the wall there. Three days total: a day and a half of preparation, then the application straight after.

Production rates, with a full crew: about fifty feet long by three feet high of grinding in a day, and around fifty square feet a day of chipping and patching where the wall has already gone loose.

The speed is not a sales point. It is a technical requirement, and the reason is the weather window.

If you prep a wall and it rains, you cannot apply — the wall is wet. If you prep and apply and the coating cures slowly, rain arrives before it sets and ruins the work. A three-day job with a ten-hour cure fits between rain events in a Toronto autumn. A slower system does not.

The work also sections cleanly. A crew can prep and coat one stretch in a single day and move to the next, and the sections bond into each other without forming a cold joint at the seam. So the schedule bends around the forecast instead of breaking on it.

What do property managers say about how it looks?

Property managers pick the colour, and in practice every one of them has chosen light grey, which reads as a deliberate trim band rather than a repair. Matching the coating to the brick is possible if a building wants the band to disappear, though no one has asked for that yet.

We have had no pushback on the appearance, and there is a straightforward reason for that. Once a brick has fallen out of a wall you cannot glue it back in. You need a patch of some kind no matter what. And at the point where the brick or the concrete has deteriorated that far, the wall needs a protective coating anyway — both to stop it happening again and to reinforce a face that has already gone absorbent. It is more requested than not.

The old method for this was aluminium cladding at grade. It cost more, protected less, and took considerably longer to install.

What to do before the next freeze

Walk the perimeter of your building and look at the bottom three feet, particularly on the elevations that face the sun and the ones where the plow banks snow. You are looking for faded, chalky-looking brick, missing units, and mortar you can pick out with a key.

If you find it, the repair happens above plus five degrees Celsius — so it is a spring or autumn job, not a February one. Same constraint that governs concrete stair and railing repair on the same buildings.

We have done this work on rental buildings, condos and exterior facade restoration across Etobicoke, where a 1950s brick wall needed the mortar rebuilt before anything could be coated. If you want the bottom three feet of your building looked at before winter, we will walk it with you and tell you what it needs.

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This article draws on repairs carried out on Toronto rental properties inspected under the City of Toronto’s RentSafeTO apartment building standards programme.