How freeze and thaw breaks brick, mortar and stone

Brick, mortar and stone all soak up some water. That is normal. The damage comes when that water freezes inside the material. Water grows as it turns to ice, and inside a brick or a joint it has nowhere to go but outward.

One freeze does very little. But an East Central Illinois winter does not freeze once and stay frozen. It freezes overnight, thaws in the afternoon sun, freezes again. Every one of those cycles pushes a little more, and over the years the masonry gives.

You will see it in a few common ways. Brick faces flake or pop off in pieces, leaving a rough, crumbly surface. That is called spalling. Mortar joints crack, go soft and fall out. Stone on a foundation or a sill sheds layers. Cracks open along a wall where water runs down it every time it rains.

• Brick faces flaking or popping off
• Mortar cracked, sandy or missing
• Stone shedding layers
• Cracks where water runs down a wall
• Loose brick at the top of a chimney

Around Hoopeston the winters are cold, but they are not steady. A week of hard cold is followed by a thaw, then rain, then another freeze. Snow melts on a sunny south wall in the afternoon and refreezes at night. Each of those swings is another freeze and thaw cycle for any brick or mortar that is holding water.

Flat ground adds to it. Water that would run off a hillside sits around a house here, soaking the lower courses of brick and the foundation for days at a time.

Freeze damage is worst wherever masonry stays wet the longest. On most houses that is a short list. The top of the chimney, which catches rain and snow and dries slowly. The bottom few courses of brick near the ground, where splashback and snow sit against the wall. Under leaking gutters and downspouts. Steps and stoops that hold water. Window sills that slope the wrong way. And foundations where the ground stays soaked.

Look at those places first. If the masonry there is sound, the rest of the house usually is too.

A lot of old brick is softer than modern brick. Softer brick soaks up more water and has less strength to resist the ice. When old brick has been repointed with a hard modern mortar, things get worse. The hard mortar does not let the wall dry through the joints, so the water stays in the brick, and the brick ends up taking the damage instead of the mortar.

That is backwards. In old work, the mortar is meant to be the weaker part, the part you replace every so often, not the brick.

Most freeze damage can be slowed a lot by keeping water off and out of the masonry. Fix leaking gutters. Run downspouts away from the house. Make sure the ground slopes away from the foundation. Keep snow from piling against brick walls. Get open mortar joints repointed before they let water deep into the wall, and get the top of the chimney looked at, because that is where the worst of it usually starts.

Sealers are sometimes sold as the answer. On old soft brick they can trap water inside, so ask before you put anything on old masonry.

Once brick faces are popping off or joints are open, it is time for repair. Spalled brick can be cut out and replaced, and open joints get tuckpointed. Doing it while the damage is small costs far less than waiting until a section of wall or a chimney has to be rebuilt.

If you are not sure how bad it is, send Brian a photo from far enough back to see the whole wall and one up close. Text it with your town to (217) 549-2230.