Ask This Old House mason Mark McCullough travels to San Diego to repair a crack in a concrete retaining wall with a stucco finish.
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Time: 2-3 hours
Skill Level: Moderate
Tools List for Repairing a Cracked Stucco Wall:
Type S mortar
1. Start by making sure the entire crack is fully exposed. This may require digging out the back side of the retaining wall with a shovel.
2. Once the full crack is exposed, take a chisel and a hammer and remove concrete on both sides of the crack until you have one continuous gap in the wall. This will make it easier to slide the mortar in. The gap should be about 1-2”.
3. Clean out the enlarged crack with a hose or a bucket of water.
4. Mix the mortar in a bucket with a margin trowel. Add a little more water than usual to allow the mortar to flow more easily into the crack.
5. Scoop up the mortar with the margin trowel and pour it slowly into the crack. Use the tuck pointer to push it firmly into place. It helps to hold a finishing trowel against the back side of the crack to keep it from pouring out. Leave about _” on the front side of the wall to leave room for the stucco pattern.
6. Allow the mortar to dry for about 1 hour.
7. Mix a new batch of mortar at the normal consistency.
8. Apply the new mortar to the front of the crack using the margin trowel until it is flush with the rest of the wall.
9. Allow the mortar to dry for about 5 minutes.
10. Using the tuck pointer, the masonry brush, and your fingers, carve out small chunks of the mortar to mimic the texture of the stucco pattern. Dampen the brush and expose some of the sand in the mortar. Do this until the texture of the patch matches the texture of the rest of the wall.
11. Allow the mortar to dry and cure for about 3-4 weeks.
12. Once the mortar has cured, apply a masonry stain to it until it matches the rest of the wall.
Mark points out that if a retaining wall is cracked or damaged, the best way to remedy the situation is to identify what caused the crack in the first place and eliminate that cause. However, in many cases, that type of solution won’t be practical for a retaining wall.
To simply alleviate the symptoms, the materials required to repair a concrete retaining wall, including the trowel, masonry brush, and mortar are fairly straightforward and easy to locate at home centers. The masonry stain can also be found at home centers. If you bring a chip of the retaining wall with you to the home center, they should be able to closely color match the stain.
Expert assistance with this segment was provided by MJM Masonry (http://mjmmasonry.com/).
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How to Repair a Cracked Stucco-Retaining Wall | Ask This Old House