Exterior brick spalling and crumbling
moderate 2–6 h
Tools: hammer and cold chisel, wire brush, tuck pointer and hawk, spray bottle, ladder, safety glasses · Materials: matching bricks (from a reclaimed-brick yard for older houses), lime mortar for pre-1930 walls, type N for newer, breathable siloxane water repellent
Steps
- Find the water: spalling clusters below a leaking gutter, at a chimney, at ground level where the wall stays wet, or under a sealer or paint that trapped moisture — fix that first or the new bricks spall too.
- Check the weep holes at the base of the wall and above windows and doors; clear blocked ones with a stiff wire so the cavity can drain.
- Chisel out a spalled brick by cutting the mortar around it, working from the centre of the brick outward so the neighbours are not disturbed.
- Brush out the cavity, dampen it, and butter a matching brick on all sides with the right mortar — soft lime mortar for old soft brick; hard mortar spalls old brick.
- Repoint the surrounding joints to the same depth and profile, and keep the new mortar damp for two days.
- Never paint or apply a film-forming sealer to brick; if you must treat it, use a breathable siloxane repellent after the repair has cured a month.
Stop and call a pro if
- spalling is spread across a large area or several courses are loose — a section may need rebuilding
- the wall is above one storey or is a chimney
- there is a crack running through many bricks in a line, or the wall bulges
- the house is a listed or protected building
What a pro does that you can't
A mason matches brick and mortar to the original, rebuilds spalled sections, restores flashing and weep holes, and diagnoses the moisture path in the wall cavity that a surface repair cannot see.
DIY cost: $40–150 in bricks, mortar and repellent