How to Replace Spalling Bricks (and When Not To)

You can replace spalling bricks, and it is a normal masonry repair. A mason cuts out the damaged units, sets new brick in fresh mortar, and blends the patch into the wall. The part that decides whether the repair lasts is not the brick. It is finding out why the faces came off in the first place.

If you are still deciding whether replacement is even necessary, read can you fix spalling brick without replacing it first. This article is for the case where the brick is gone enough that it has to come out.

Why did the brick spall in the first place?

Spalling is the face of a brick flaking, peeling or popping off. Two causes show up again and again in the technical literature. Salt crystallizing inside the brick builds pressure that can make the outer surface spall or delaminate, and freeze-thaw of saturated brick is another cause (National Park Service and Brick Industry Association). Both need water in the brick.

On older Chicago brick there is a third pattern: a mortar that is harder than the brick. The National Park Service says repointing mortar must be softer and more vapor-permeable than the brick, because a mortar stronger than the masonry causes cracking and spalling of the brick (National Park Service). When the mortar will not let moisture out, it moves out through the brick face instead, and the face pops off (National Park Service).

That is why replacing bricks without looking at the cause is a short-term fix. Put new brick next to hard mortar, a leaking parapet or a clogged downspout, and the new brick can end up in the same condition. For how water does this damage over a Chicago winter, see how freeze-thaw damages brick.

How are spalled bricks replaced?

The steps below are the general order a mason works in. Your wall may need changes to it.

1. Find the moisture source. Check the roof edge, coping, flashing, gutters, downspouts, and the mortar on the nearby joints. Fix what is feeding water into the wall, or plan to fix it in the same job.
2. Mark the damaged units. Not every spalled brick needs to come out. Bricks that have lost a thin face may still be sound behind it. A mason sorts the ones that are losing material from the ones that have simply stopped.
3. Remove the bad brick and the mortar around it. The mason cuts out the unit without damaging the bricks beside it. Old mortar comes out of the joints by hand chisel or by a carefully run grinder. The National Park Service guidance on joint preparation calls for removing mortar to a depth of 2 to 2.5 times the joint width, which is usually about 1/2 to 1 inch (National Park Service).
4. Set the new brick. The new unit goes in with fresh mortar, laid to line up with the courses around it, with the joints filled solid.
5. Tool and match the joints. Mortar color is driven mostly by the sand, so the mason matches sand color, texture and the tooling of the old joints. The NPS recommends a test panel to set the standard of work before the whole job proceeds (National Park Service).
6. Protect the work while it cures. Fresh mortar needs protection from freezing and from drying too fast. In a Chicago shoulder season that matters.

The mortar choice matters as much as the brick. The mortar for a patch on old brick should follow the same rule as repointing: softer and more permeable than the surrounding brick, and no harder than the original mortar (National Park Service).

Do you need a permit to replace spalled bricks?

Often yes, and the line is a specific number. The City of Chicago lets owners of residential buildings up to four stories (and accessory buildings like garages) replace up to 50 square feet of masonry in kind, meaning the same material, size and shape, without a building permit (City of Chicago). Past that, you are in permit territory.

For larger masonry repair the City runs most of it through its Express Permit Program. The Express masonry page covers routine repair, replacing the outer layer (wythe) of a wall, and similar work. It does not cover rebuilding all wythes of an exterior wall; that goes through a different review (City of Chicago).

Two other points:

• Who pulls it. A masonry permit requires a City-licensed mason contractor (City of Chicago). That license covers work in brick, stone, concrete and similar materials, and the business must have at least one person who passed the City's mason exam (mason contractor license).
• Owners. If the building is your primary residence, three stories or fewer with six or fewer units, you may be able to act as your own contractor for one property per calendar year (City of Chicago). You then take responsibility for safety, inspections and code compliance (City of Chicago).

If scaffolding, a dumpster or materials will sit on the sidewalk or alley, that is a separate permit from the Chicago Department of Transportation (City of Chicago). Rules and fees change, so confirm what applies to your building with the Department of Buildings before work starts. Our brick repair permit explainer walks through the whole picture.

When does one brick become a bigger job?

Replacing a few spalled units is one thing. These are signs the problem is larger:

• Spalling across a whole section of wall instead of scattered bricks.
• Bricks that are spalling again after an earlier repair.
• Cracks that follow the mortar joints in a stair-step pattern, or a wall that bulges.
• Brick falling or loosening near a window, a parapet or a walkway.

The City expects owners to keep exterior walls in good repair and the masonry joints weather resistant and water tight (City of Chicago). Loose brick over a sidewalk is also a public safety problem. If any brick is loose enough to fall, treat it as urgent and keep people away from the area below it.

What drives the cost?

We do not quote prices in an article, because the answer depends on the wall. These are the things that move the number:

More on the pricing side in what drives brick repair cost in Chicago.

What should you ask a mason before they start?

1. What is causing this brick to spall, and what are you doing about it?
2. Will you replace only the failed units, or a larger section?
3. How will you match the brick and the mortar? Can I see a sample?
4. Who is pulling the permit, and what is the number?
5. What happens if you open the wall and find more damage?

Our masonry crew can look at the wall and tell you whether it is a few bricks or a bigger repair. For the full picture of Chicago brick work, see the owner's guide to brick and masonry repair.

Common questions

This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.