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How to repair minor damage to a cinder-block wall

“I never advise painting basement walls, even with epoxy paint,” contractor Rob Robillard said.HANDOUT

Q. My house was built in the ’40s and has a cinder-block foundation. On the inside, it has paint that’s peeling. Some of the blocks are crumbling, but the problem is not deep, less than an inch. In some places there is a light-pink tinge to the wall. The wall appears solid, however, and there doesn’t seem to be any bulging. How do I fix the wall (get rid of the pink, if needed), and what should I fill and/or cover it with?


A. I never advise painting basement walls, even with epoxy paint. It sounds like you might have moisture coming through the concrete blocks. Can you see mold? Start solving this issue by addressing water management outside the house:


■  Correct any downspout problems, ensuring that water is draining to at least 10 feet away from your foundation;

■  Ensure the yard slopes away from your foundation — ideally at least 6 inches over 10 feet;

■  Add gutters if needed, and make sure the ones you have are not clogged.

Meanwhile, to hold the problem at bay, run a high-quality dehumidifier in your basement, one that doesn’t let the humidity go above 45 percent.

Once your drainage is addressed, strip off the paint and repair the wall’s mortar joints. Here’s how:

1. Remove loose mortar with a cold chisel and hammer;

2. Use a wire brush to clean the area thoroughly and a shop vacuum to remove the dust;

3. Apply new mortar into the joint, following the manufacturer’s instructions on the bag for mixing and application;

4. Use a U-shaped joint trowel to push the mortar into the joint and to smooth it out.

5. Clean any excess while the mortar is wet.

Q. Thank you for your column in the Sunday Globe. I read it faithfully. Awhile ago you wrote about tile grout breaking down and leaking water into the pan beneath, causing all sorts of damage (“Shower-tile buildup could be drain on finances,” Jan. 29). We recently installed a new shower with 1-inch floor tiles. I’m worried it will leak someday. Is there some way to treat or care for this floor to avoid grout damage (short of not taking any showers)? Should I apply a certain kind of sealant?


JOHN C., Kittery, Maine

A. Hi, John, thank you for reading. All things leak at some point, I’m afraid, but I would seal your grout every two years. So what about the tiles themselves, do they need sealing? All unglazed tile and any non-epoxy grout applications should be protected with a penetrating sealer. This type of tile has microscopic imperfections that will accumulate gunk and make your floor look dirty.

Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @globeaddress or @robertrobillard.