Stucco is a durable exterior finish made of cement, aggregates, and water that is commonly used for exterior siding on homes. While stucco stands up well to weathering, it can sometimes develop cracks or pores that allow water to seep in, leading to damage over time if not addressed. The key to fixing water-damaged stucco is completing repairs promptly before the moisture causes further deterioration.
Assessing The Damage
Look for signs like peeling paint, blisters or bulges in the stucco, grey or black staining, cracking, or soft, mushy areas. Use a utility knife to carefully cut open any bubbles or swelling to check for moisture. You can also hire a professional to perform moisture or infrared testing to determine the extent of the wet area behind the stucco. Minor isolated patches may only require minor repairs. But widespread or deep moisture likely means replacing larger sections.
Preparing The Surface
Start by chiseling or grinding away any loose, cracked, or delaminated material from the walls. Use a wire brush to scrub away dirt, debris, or algae growth that may remain. This prepares a clean, firm surface to which the new stucco can adhere. Now is also a good time to check for and repair any cracks or gaps that may be allowing moisture to enter. Apply a bonding agent made for stucco repairs with a roller or brush to coat the prepared area.
Repairing The Stucco
Mix up a small batch of pre-blended stucco patching compound according to package directions. Many pros recommend using a stucco with a factory color additive for the best color match. Apply the scratch coat, the first thin layer of stucco, with a trowel using firm horizontal strokes, allowing it to “rough up” the surface slightly for better adhesion of the next coat. Scratch up the coat within 20 minutes as it starts to dry. Once dry, apply the thicker brown coat layer in a similar manner. Allow the brown coat to cure for at least 24 hours before applying your final texture coat.
Apply the finish coat by hand troweling or spraying, depending on the texture you need to match. Reproduce any swirl, dash, or skip trowel patterns you see in surrounding areas. Once dry, examine your work and use an abrasive pad or grinder to blend and smooth any imperfections before they cure fully.
Finishing Touches
After sanding, wipe away any dust from repairs, and inspect for and seal any tiny cracks you missed previously. Once fully cured, you can paint to match the existing color if desired. Some people choose to leave the natural cement color for an attractive contrast on small patches.
What Type Of Bonding Agent Should Be Used For Stucco Repairs?
There are a few different types of bonding agents that can be used for stucco repairs, and the ideal one will depend on the specific situation. Here are some good options to consider:
- Acrylic Bonding Agents: These are water-based and contain acrylic polymers that help the new stucco adhere well. They bond easily to multiple surfaces and don’t require extensive surface preparation.
- Latex Bonding Agents: Similar to acrylic, natural latex is used instead of polymers. They provide a strong bond and aren’t as brittle as some cement-based options.
- Masonry Bonding Agents: For repairing stucco over cement board, concrete, or masonry, an agent with a high cement content works well. It penetrates these porous substrates better than some others.
- Elastomeric Bonding Agents: For problem areas or stucco in constant movement, an elastomeric agent has more flexibility to bridge minor cracking and shifting.
- Multi-Purpose Bonding Agents: These contain polymers, latex, and cement for strong adhesion to various substrates with less surface prep than cement-only options. They are more forgiving to use.
How Can You Prevent Future Water Damage To Stucco?
- Ensure proper drainage around the house. Make sure gutters are cleaned and drain water at least 6 feet away from the foundation.
- Add or repair flashing around windows, doors, roof lines, and other areas where two different materials meet.
- Consider installing a rain screen behind the stucco to allow moisture to escape instead of getting trapped.
- Maintain exterior caulking and sealants around issues like hose bibs, pipes, vents, etc., to prevent leaks.
- Inspect for cracks in the stucco a few times a year, especially after storms, and make repairs promptly.
- Ensure the roof doesn’t leak and direct water away from the walls. Clean gutters/downspouts regularly.
- Add waterproof paints or sealants made for masonry as a protective coating on the stucco surface. Reapply every few years.
- In very wet climates, consider installing a drainage plane layer behind the stucco for extra moisture protection.
- Trim back any trees/shrubs so branches don’t scrape the stucco as they grow.
- Check the foundation for cracks or moisture issues that could transfer through to the stucco.
- Prompt maintenance is key to keeping water damage at bay long-term.
Conclusion
Repairing water damage in stucco is necessary to prevent further deterioration and structural issues. Following the proper procedures around assessment, surface preparation, patching, and sealing will restore stucco safely and effectively. Just as importantly, implementing preventive measures around drainage, flashing, and routine maintenance will help keep repaired stucco protected long into the future.
