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2018 National Home Improvement Estimator, All Rights Reserved Page 37

Chapter 3, Foundations and Slabs

Many older homes have foundations that have cracked or settled. Check the foundation wall for
deterioration that could allow water to enter the basement. Check both foundation walls and piers for
settling. Windows or door frames out of square or loosened interior wall finish suggest that the
foundation has settled. The next chapter explains how to correct minor settling by jacking and
re-leveling beams and floor joists. Individual piers can be replaced. But if the pier has stopped settling,
jack the supported girder or joist and add a block to the top of the pier.

Most concrete foundation walls develop minor hairline cracks that have no effect on the structure.
However, open cracks may indicate a failure of the foundation that’s getting progressively worse. To find
out if a crack is active or dormant, scratch a line at the end of the crack and wedge a nail tightly into the
crack. If the crack grows beyond the scratch mark or if the nail can be removed easily several months
later, the crack is probably active.

If a crack is dormant, it can be repaired by routing and sealing. Enlarge the crack with a concrete saw
or by chipping with hand tools. The crack should be routed 1-1/4" or more in width and about the same
depth. Rinse the joint clean and let it dry. Then apply a joint sealer such as an epoxy-cement
compound in accord with the manufacturer's instructions.
Active cracks require an elastic sealant. Again, follow the manufacturer’s instructions. Good-quality
concrete sealant will remain pliable for many years. The minimum routing depth and width for these
sealants is 3/4". The elastic material will deform but maintain a tight seal as the crack moves. You
could also apply a strip sealant over the crack. But these protrude from the surface and make a poor
choice if the wall is visible from the building exterior.

Repair loose mortar by brushing thoroughly to remove dust and loose particles. Before applying new
mortar, dampen the clean surface so that it won’t absorb water during repair. You can buy premixed
mortar with the consistency of putty. Apply mortar over the cavity as if you were filling a void with
painter’s caulk. For a good bond, force mortar into the crack. Then smooth the surface with a trowel.
Cover with a vapor barrier for a few days to keep the mortar from drying too fast.

Damp or leaky basement walls are usually caused by clogged drain tile, clogged or broken downspouts,
cracks in walls, or by water that puddles against the foundation. Look for downspouts that empty
against the foundation wall or surface drainage channeling by the foundation. For a dry basement, keep
water away from the foundation by proper grading.