Brick: Exterior Care and Cleaning

Few materials carry an air of permanence like brick. Fired clay stands up to sun, rain, fire and decades of weather with almost no attention, which is exactly why homeowners tend to assume there's nothing to attend to. But "nearly maintenance-free" is not the same as invulnerable, and when a brick wall does begin to fail, the brick is rarely the culprit.

Two things quietly decide how a brick exterior ages, and neither is the brick's toughness. One is the mortar between the bricks — softer, thinner, and far quicker to weather than the units it binds. The other is water, and specifically how it moves through the wall. Get those two right and brick will comfortably outlast the rest of the house; get them wrong and you can undo a century of durability with a pressure washer or the wrong sealer.

What actually fails first

Look at any old brick wall that's in trouble and follow the damage — it almost always runs along the joints, not across the faces. Mortar is designed to be the sacrificial, renewable part of the assembly. It weathers, it erodes, and eventually it needs replacing, a process called repointing. A hard-fired brick can outlive several generations of the mortar around it.

That hierarchy is worth keeping in mind everywhere brick appears, because the exposure varies by location. Full walls and veneer take ordinary weather; chimneys get it from every side at once and rank among the harshest-worn brick on any house; foundations and knee walls near grade stay damp from splashback and ground moisture; and steps, patios and garden walls collect standing water and organic growth in shaded spots. In each case, it's the joints and the wettest areas that show wear first — and when repointing does come due, the new mortar should be matched in hardness to the brick, because mortar that's too hard will damage softer historic brick rather than protect it.

Brick manages water — it doesn't repel it

Here's the point that reframes almost every brick problem: a well-built brick wall is durable because it manages moisture, not because it keeps every drop out. Small amounts of water pass into the masonry and evaporate back out as conditions change. The wall breathes. Trouble starts only when that cycle is blocked — when water gets in and then can't get out, whether because flashing and drainage failed, the wall stays saturated, or a non-breathable coating has sealed the moisture inside.

Trapped water drives the two classic brick complaints, and both are water stories rather than dirt stories. Efflorescence — the chalky white bloom that appears on the surface — is simply mineral salts left behind as moisture evaporates out of the masonry; it's cosmetic, but it's the wall telling you water is moving through it. Spalling — where the face flakes or pops off the brick — is the structural one, usually caused by trapped water freezing and expanding inside the unit, and it's most common on softer brick or behind a coating that locked moisture in. This is precisely why sealing brick with the wrong product backfires: it traps the very water it was meant to exclude. If you do seal, choose a vapor-permeable product and test a small area first. Our guide on efflorescence on brick goes deeper on the white bloom specifically.

Cleaning a joint-sensitive surface

Because brick is porous, it holds onto whatever lands on it — organic algae, moss and mildew on damp, shaded walls; general atmospheric grime, worst near roads and grade; rust streaks from metal fixings and railings; leftover mortar smears and paint; and carbonate runoff washing down from limestone or concrete above. The treatment depends on the stain: organic growth responds to gentle cleaning solutions, efflorescence brushes off dry, and rust or paint needs a targeted, masonry-safe remover used with care.

Whatever the stain, a low-pressure, chemistry-first routine does the job with the least risk:

1. Rinse loosely with plain water to knock off surface dust and wet the wall so it doesn't drink cleaner too fast.
2. Apply a masonry-safe cleaning solution suited to the stain — a mild detergent or dedicated masonry cleaner.
3. Agitate with a soft or medium bristle brush, working the joints and face. Never a wire brush, which scratches and leaves rust-prone metal deposits.
4. Let it dwell briefly per the product's guidance, without letting it dry on the wall.
5. Rinse gently from the top down.
6. Test any stronger cleaner on a small, hidden patch first, keeping acids and bleach off adjacent metal, plants and mortar.

A pressure washer sits firmly on the cautious end of that scale. The brick face is hard, but the joints are not — a concentrated stream held too close will carve out soft or aging mortar and force water deep into the wall, feeding the trapped-moisture problem you're trying to avoid. Sound, modern, hard-fired brick tolerates moderate pressure with a wide fan tip held well back and kept moving; old, historic, soft or crumbling brick should be soft washed instead. When unsure, start gentle. For a full walkthrough see how to clean exterior brick, for green growth removing algae from exterior walls, and for the pressure decision, pressure washing versus soft washing.

Keeping the water moving away

Brick asks for little, and most of what it does ask is about redirecting water rather than cleaning it. Confirm that gutters, downspouts and flashing send runoff away from the wall instead of onto it. Keep soil, mulch and sprinklers from constantly wetting the lower courses. Repoint failing mortar before joints crumble and open a path inward. Clear organic growth early, before moss mats hold moisture against the wall. And rethink any coating on brick that's already spalling, since it may be the thing trapping water.

The signs worth watching are, once again, mostly moisture clues.

Fine hairline surface marks are usually cosmetic. Stepped cracking that follows the mortar joints, bulging walls, or widespread spalling deserve a professional evaluation. On the whole, brick sits at the durable end of the exterior spectrum — its practical lifespan is limited not by the clay but by the joints and by water management. Keep the mortar sound and the water moving away, and brick will outlast the painted and organic materials on the same house by a wide margin. It shares that porous, water-managing character with concrete and stucco.

Related guides

• How to clean exterior brick
• Efflorescence: white residue on brick
• How to remove algae from exterior walls
• Pressure washing vs. soft washing
• Concrete: exterior care and cleaning
• Stucco: exterior care and cleaning