Q: I have brick stairs with a landing leading to my entry door in my San Francisco home. The brick and mortar is original (about 1928), and during the recent rains, I have noticed that the wood beneath the stairs gets wet.
I have power-washed the bricks and mortar and the edge of the stairs where the mortar and the stucco meet. How can I make repairs or will I need to replace the stairs in the next several years?
A: With any luck you’ve caught the problem in time, and with some attentive preventative maintenance, you can avoid replacing your brick stairway.
We think it’s likely the source of the seepage is failing mortar joints between the bricks. It’s less likely that the seam where the brick meets the stucco is the source of the leak.
In any case you would be wise to address both areas.
Brick stairs like yours are constructed by first building a wooden ramp as a form for the staircase. Treads and risers are then built from the bottom to the top of the staircase. The tread is the part of the stair you place your foot on, the riser the vertical portion.
As each step is completed, the mason backfills the open space between the wood ramp, the tread, and the riser with mortar. This creates a solid step. The wood you see is actually the base of the stairs.
If this wooden base is subject to constant moisture, in time it will fail. Most important, since there is probably no reinforcing steel in the staircase, the stairs will eventually fail without the wood support structure.
We’d recommend that the first thing you do is determine the condition of the wood under the stairs. If the wood is solid, that’s great. If not, we recommend that you remove and replace the fungus-damaged wood and add some bracing for additional support. If you suspect termites, we suggest you contact a licensed pest control operator to treat the area.
Next, check the condition of the mortar. Try to remove some of the mortar from one of the joints with a stiff paint scraper. If the mortar comes out easily, you have to repoint all the joints. If the joints seem solid, the source of the leaks is probably the seam between the treads and risers.
To point a joint, start by scraping about 3/4 inch of mortar out of each joint. Brush the joint thoroughly with a wire brush to remove any loose mortar. Pay particular attention to the seam where each tread meets a riser and the joint where the top tread meets the landing.
Mix a small batch of mortar to a consistency a little thicker than toothpaste. Wet each joint with water (a spray bottle works well) and press the mortar mixture into the joint. We use packaged mortar mix and enrich it with Portland Cement.
Let the mortar dry for 10 minutes or so and scrape off the excess. If the joints have been tooled, you can use a masonry tool made especially for tooling joints to produce the concave surface. But we’ve found that a piece of 1/2-inch pipe works just as well.
Let the mortar dry for a couple of hours and rinse off any cement film that may remain. If any residue remains on the brick, remove it with a solution of muriatic acid. Be careful. It’s very caustic. Make sure to read the manufacturer’s instructions and wear rubber gloves and eye protection; acid will burn.
Finally, inspect the side of the stairs where the brick meets the stucco. We doubt that this is the source of your problem, but if you see a crack, caulk it with a good latex caulk and paint it.
Remember, the devil is in the details. Repointing brick and caulking meticulously may extend the life of your stairs by decades and save you the thousands of dollars it would cost to have them rebuilt.