Masonry Troubles Need Fast Repairs

Bricks, blocks and other masonry are among the most trouble-free of building materials. But even masonry is not immune to damage caused by moisture, settling or impact.

It’s important to repair masonry as soon as you discover the damage. If neglected, small problems that are easy to fix can become major ones that require a mason’s attention.

A common problem is efflorescence, a white powdery substance found especially on new masonry surfaces. It occurs when internal moisture dissolves soluble salts present in concrete or mortar.

The salt solution migrates to the surface and evaporates, leaving behind deposits of crystallized salts. Moisture in fresh mortar makes new structures especially prone to efflorescence. Masonry walls exposed to rain during construction may also develop the condition.

In itself, efflorescence is more an aesthetic problem than a house-threatening one. You can remove the powdery residue by scrubbing it with a stiff-bristled brush and water.

But if it continues or if it appears on older masonry, it may signal a more serious problem. Look for an entry point for moisture, such as cracks, crumbling mortar and deterioration around windows, doors and chimneys. Also check for dampness caused by moisture-saturated soil against masonry below ground.

Dampness in below-ground masonry is difficult to cure. The soil around the masonry must be drained. If the masonry is a foundation wall, first make sure that the gutters are not clogged and that downspouts have drainage that carries runoff away from the house. Sometimes the soil needs to be regraded so that it slopes away from the foundation.

Cracked or crumbling mortar joints allow moisture to penetrate the wall, where it can freeze, causing even more expensive damage. The process of fixing mortar joint--called repointing or tuckpointing--involves chiseling out damaged mortar and replacing it. New mortar should match the old as closely as possible in composition, color and joint profile. This is especially important when repointing very old or historic masonry, whose mortar may differ significantly in strength and flexibility from modern mortars. In this case, contact a preservation agency for the name of a mortar analyst.

Like defective joints, cracked or crumbling bricks weaken a wall by letting in moisture. Replace such bricks as soon as possible. If damage is in a critical load-bearing area, such as above or below a window or doorway, consult a mason.

A long vertical crack in a concrete or brick wall may result from normal settlement of a new building. When the building has settled, the crack will stabilize and can be filled. But if such cracks open again after being filled, there may be a serious movement of the earth beneath the structure or a flaw in the foundation. Call in an engineer to evaluate.

A loose, broken, sunken or raised brick in a patio or a walk can be hazardous. Bricks laid in sand are likelier to shift than mortared bricks but are easier to fix. Remove an out-of-level sand-laid brick with a pry bar, then take out the surrounding bricks by hand. Remove or add sand as needed and tamp it down well. When the bed is level, reinstall the bricks, replacing any damaged ones. Sweep fresh sand into the joints.