White powder on the brick after rain, or every spring
You walk past the side of the house and the brick looks dusted with chalk. It wasn't there in summer.
That's efflorescence. The Brick Industry Association explains it simply: water with dissolved salts reaches the surface, the water evaporates, and the salts stay behind. It needs three things: salts, water to dissolve them, and a path to the surface.
The salt usually isn't from the brick. It more often comes from what touches the brick, like mortar, concrete or soil. It just shows best on darker brick.
It's often seasonal. The National Research Council Canada's digest on efflorescence notes that cool fall weather brings the salts out, and by summer they've generally gone.
What the white powder is telling you
New walls often bloom in their first year. On an older house it means something else.
The Brick Industry Association says efflorescence on an established building that used to be clean usually points to a new source of water. After the first year, it's generally down to water getting in or poor drainage. Where it shows up on the wall is a clue to where the water enters.
So read it like a map: under a downspout, near the ground, below a sill.
Is efflorescence dangerous?
Usually not to the wall. The Brick Industry Association calls it undesirable but usually not harmful to brick masonry. The NRC digest adds a caution: salt crystals growing near the surface can damage masonry.
The bigger worry is the water behind it. Water that keeps carrying salt out is also soaking the brick and the joints.
Two things make it worse, per the same Brick Industry Association note. Washing it off in cold weather puts more water in the wall and can bring up more salt. Sealing the face can trap the salts just under the surface, where they can push the brick face off. The City of Hamilton's Masonry Restoration Guidelines warn about sealers on old brick too.
Mortar that comes out like sand
Rub a joint with your thumb. If it sands out, or you can push a key into a gap between bricks, the mortar has worn through. Hamilton's Masonry Restoration Guidelines call mortar the sacrificial part of the wall. It's meant to wear over time, so old walls need their joints redone now and then. Usual causes, from the same guidelines: water getting in, wetting and drying, freeze and thaw, salt crystals, and earlier repairs with the wrong mortar.
A leak can do it in one spot. The US National Park Service's Preservation Brief 2 shows mortar washed out of a wall by a leaking downspout.
What's safe to check from the ground
Stay on the ground: no ladders, no chemicals.
- Walk the house after a rain. Note where the brick stays dark longest.
- Look up at eavestroughs and downspouts. Is water spilling over or dumping against the wall?
- Check where the white powder sits: under a sill, near a downspout, or along the bottom rows.
- Look for joints that are recessed, cracked or missing, and for bricks that look loose.
- Indoors, look for damp or damaged plaster on that wall.
A dry, stiff brush usually takes the powder off. That's as far as the DIY goes. If bricks are loose, cracked or flaking, stop there and send us a photo.
What repointing is
Repointing is the general name for this kind of repair. Preservation Brief 2 defines it as removing deteriorated mortar from the joints and replacing it with new mortar. Done well, it restores the wall. Done badly, it can damage the brick itself.
The mortar matters most. Both Preservation Brief 2 and the City's guidelines say the new mortar should be softer and more permeable than the brick. Then moisture leaves through the joints, not the brick. Hard mortar on soft old brick traps water, and the brick face can pop off.
When the joints are due
Not every joint needs work. The City's guidelines say to work only where mortar is loose or crumbling. If the joint is firm and still bonded on both sides, leave it.
The signs that a wall is due, from Preservation Brief 2: disintegrating mortar, cracks in the joints, loose bricks, damp walls, or damaged plaster inside.
The same brief is clear on the order. Fix the cause first, whether that's a leaking roof or eavestrough, water rising from the ground, or settlement. Otherwise the new joints wear out the same way.
If your house is a designated heritage property
The City of Hamilton's Masonry Restoration Guidelines cover houses designated under the Ontario Heritage Act or in a Heritage Conservation District. Before any work, you must consult the City's Planning and Economic Development Department. The work may need a building permit, a heritage permit, or both. If you're not sure whether your house is designated, ask the City first. Our permits page has more on Hamilton permits.
What we do
Albany Contracting Group does brick repairs on Hamilton houses. We look at the whole wall with you: where the water comes from, which joints are worn, which bricks are damaged. Then we fix the mortar joints and replace damaged brick. We'll also point out what to sort out first, like a downspout soaking the wall. It's all priced at the free in-home consultation, once we've seen the wall.
Bricks flaking too? Read why bricks flake. See our brick repair and masonry work.
