Brick faces spalling or flaking off: why it happens and what replacement costs

Brick faces that pop off in sheets, flake like a pastry, or crumble to red dust are spalling: water got into the brick, froze, and blew the fired skin off. The units themselves get cut out and replaced at $20 to $40 per brick, with small spot repairs running $300 to $900. The important part is that spalling is almost always a symptom. Something is keeping those bricks wet, and until that is fixed the new brick does the same thing.

Check this first (fifteen minutes, from the ground)

1. Map where it is. Photograph every spalled area. Spalling clusters. A vertical stripe means a downspout or a valley above. A band at the bottom two or three courses means splashback or a grade problem. A patch under a window means the sill.
2. Compare the joints beside the failure. If the mortar joints are hard, grey, and standing proud of the brick while the faces are gone, someone repointed soft brick with hard modern mortar and the brick has been taking the freeze-thaw damage ever since.
3. Feel the depth. Lost skin only, maybe an eighth of an inch, is a slow problem. Units eaten back half an inch or more are structural loss in that unit.
4. Look for paint or a sealer. Painted or sealed brick that is now spalling is a trapped-moisture failure. The Indiana DNR’s brick guidance names painting and sandblasting as the two treatments that ruin historic brick, and Evansville has a lot of both from the 1970s.
5. Check inside. Damp plaster, blistered paint, or white powder on the interior wall opposite a spalled area confirms the wall is wet through.

What is usually wrong

Full ranges are on the pricing page, and the brick repair page explains how a matched unit is sourced and set.

Why Evansville brick spalls

A brick is fired clay with a hard skin and a softer, more porous middle. Break the skin, or hold water against it, and Evansville’s winter does the rest. NOAA’s 1991-2020 normals for Evansville Regional Airport count 92.6 nights a year at or below 32 degrees but only 15.5 days that stay frozen, which is roughly 77 freeze-thaw cycles a year. Add 45.31 inches of annual rain, with 4.60 inches in March and 5.14 in April while freezing nights are still happening, and any saturated brick face gets worked loose.

The second driver is chemistry. The National Park Service’s Preservation Brief 2 is blunt: repointing mortar must be softer and more vapor permeable than the masonry units, because moisture has to leave the wall through the joint rather than through the brick. Type S mortar tests around 1,800 psi and Type N around 750, against Type O at 350 and Type K at 75. Put 1,800 psi mortar into a wall of 1880s Evansville brick and the joint will not give, so the brick face becomes the sacrificial part. That single mistake, repeated across Riverside, Goosetown, Bayard Park, and the West Side since the 1950s, is behind most of the spalled brick in this city. The mortar page has the whole comparison.

When it is structural, not cosmetic

Face loss is a durability problem. It becomes structural when the loss goes past the face into the body of the unit across many bricks, when a unit moves under hand pressure, when a whole wythe has separated, or when the wall bulges. Those cases are on the loose or fallen bricks and bowing brick wall pages, and both are worth a look before anyone quotes you a cosmetic repair.

What to expect on the call

Photos first: a wide shot of the elevation, close-ups of the spalled area with a coin for scale, and a shot straight up showing the gutter and downspout above it. Expect to be told the water source before the brick count. Matching matters: a hand-molded 1880s unit usually comes from salvage or gets cut down from a whole brick, which is why the per-unit range runs to $40. Ask for the mortar type in writing, and if the house sits in a preservation area, check the historic district masonry rules before scheduling. Work happens April through November because mortar needs wall temperatures between 40 and 95 degrees.