Stucco is a durable, attractive exterior finish for homes and buildings. Over time, stucco can develop cracks, crumbling sections, and other damage that detracts from its appearance and protective abilities. Repairing damaged stucco restores the finish to its original beauty while preventing further deterioration of the underlying structure. With the right materials and techniques, DIYers can successfully repair stucco damage.
Assessing Stucco Damage
Before beginning any stucco repair project, carefully inspect the area to determine the type and extent of damage. Look for:
Cracks
Cracks in stucco can range from hairline fractures to gaps of 1⁄2 inch or wider. Very thin cracks may only require sealing, while wider cracks need to be filled with stucco patch.
Inspect the length, width, and depth of cracks. Cracks that run vertically or diagonally are especially concerning, as they may indicate shifting of the structure or foundation. Tapping along the length of cracks can reveal areas of hollow sounding stucco, indicating deterioration behind the surface.
Crumbing or Missing Sections
Areas of stucco that have crumbled, flaked, or fallen away expose the substrate beneath. This causes further damage over time as water infiltrates behind the stucco. Any missing sections must be replaced and bonded to the existing finish.
Discoloration or Staining
Stains and discoloration do not affect the structural integrity of stucco but detract from its appearance. Algae, dirt, rust from nails, and mineral deposits from water runoff can all stain stucco. For cosmetic repairs, use a stucco paint or whitewash.
Moisture Damage
Excess moisture behind stucco causes serious structural issues as it deteriorates the substrate and framework. Signs include stucco blistering, peeling away from the substrate, or forming a loose powder. These indicate that water is getting behind the finish and must be addressed before further repairs.
Tools and Materials for Stucco Repair
Repairing stucco involves specialized materials to patch, seal, replace, and refinish the damaged sections. Gather the following equipment and supplies:
- Safety gear – Work gloves, safety goggles, dust mask
- Drop cloths
- Bucket, stir sticks, and mixing paddle
- Stucco repair compound
- Bonding agent
- Acrylic additive
- Paintbrush, trowel, and finishing tools
- Sandpaper – 80-grit and 120-grit
- Wire brush
- Chisel
- Masonry drill and screw anchors
- Masking tape
- Primer and exterior paint or whitewash
Stucco patch: Use a premixed stucco repair compound designed for patching vertical surfaces. It should contain Portland cement and have a similar composition and texture to the existing finish.
Bonding agent: This liquid additive improves adhesion of the fresh patch to existing stucco. Look for a polymer-modified acrylic bonding agent.
Acrylic additive: Adding a small amount of acrylic to the stucco mix makes the patch more flexible and workable.
Paint or whitewash: Match the color of the existing finish when possible. Whitewash may be used to refresh stucco’s appearance without fully painting.
How to Repair Stucco Cracks
Hairline cracks and fractures up to 1/16 inch wide can often be repaired by simply sealing them with elastomeric sealant. Follow these steps:
Prep the Crack
- Use a wire brush to remove any loose debris inside the crack.
- Widen the crack slightly using a masonry drill to allow sealant to penetrate. Drill into the crack 1⁄2 inch deep or less.
- Clean away dust with a damp cloth. Let the area dry completely.
Apply Sealant
- Load caulk gun with elastomeric polyurethane sealant and insert plastic nozzle tip into crack.
- Slowly fill the crack, moving the tip to distribute sealant evenly and reach full depth.
- If necessary, smooth with a moistened fingertip before sealant skins over.
- Allow 24 hours for sealant to fully cure before painting or applying other finishes.
For cracks wider than 1/16 inch, use stucco patch:
Prep the Crack
- Use a chisel and hammer to open the crack into a “V” shape, at least 1⁄2 inch deep.
-Brush and vacuum out debris.
Mix and Apply Patch
- In a bucket, mix stucco repair compound, bonding agent, water, and a small amount of acrylic additive.
- Fill the crack with the patch using a trowel or putty knife.
- Smooth the patch flush with the surrounding surface.
- Allow to cure 24 hours before finishing.
Fixing Damaged or Missing Sections
For stucco damage exceeding a few cracks, you’ll need to cut out the affected area and replace it with new material:
Prep the Area
- Mark the boundaries of damaged area to be removed. Make square or rectangular lines.
- Use a masonry drill to make holes at the corners and along edges.
- Use a chisel and hammer to tap connecting lines between holes.
- Carefully cut out the damaged section by hand or with an oscillating multi-tool.
- Scrape or sand the edges to expose fresh stucco.
Replace the Section
- Brush bonding agent along the removed edges. Let dry 5 minutes.
- Mix stucco patch to a stiff, doughy consistency.
- Press new stucco patch into place, ensuring full contact with edges.
- Fill any gap behind with foam backer rod before patching.
- Flatten, smooth, and blend the patch using a trowel and float. Allow to cure 24 hours.
Blend Texture
- Once fully cured, use 80-grit sandpaper to smooth the patch.
- Match the surrounding texture by roughing up the patch with a trowel.
- On smooth finishes, skim coat patch with thin layer of stucco compound.
How to Resurface Damaged Stucco
If stucco damage covers a large wall section, it may be best to re-apply a fresh layer of stucco over the damaged area:
Prep the Surface
- Use a wire brush to remove all loose material.
- Clean dirt, algae, and debris with pressure washer.
- Sand rough spots to smooth.
- Apply concrete bonding agent and allow to dry.
Apply New Base Coat
- Mix stucco base coat compound per manufacturer instructions.
- Trowel 1/8 to 1⁄4 inch layer over damaged area, embedding reinforcing mesh.
- Smooth with a float, removing trowel ridges.
- Allow to cure 24-48 hours.
Apply Finish Coat
- Mix finish coat stucco compound. Add acrylic fortifier.
- Trowel thin, even layer over cured base coat.
- Texture to match surrounding stucco using float or special trowel.
Blend Edges
- Feather out edges where new and old stucco meet.
- When cured, blend further by sanding if needed.
How to Paint Stucco
Painting is an easy cosmetic fix for discolored, stained, or marked up stucco. Follow these guidelines:
Clean the Surface
- Use a pressure washer with detergent to remove dirt, mildew, and chalky deposits.
- Spot clean oil stains with degreaser.
- Rinse thoroughly and allow to dry fully.
Make Needed Repairs
- Inspect for cracks, deteriorated sections, moisture issues.
- Repair larger problems before painting.
- Seal hairline cracks with caulk.
Apply Primer
- Use high quality acrylic or elastomeric primer made for stucco.
- Roll on primer and allow 2-4 hours to dry.
- Look for unpainted spots and apply second primer coat if needed.
Paint the Stucco
- For best adhesion, use high quality 100% acrylic exterior paint.
- Cut-in edges with brush and roll paint onto the main surface area.
- Work in 3×3 foot sections and maintain a wet edge.
- Let cure 24-48 hours before second coat.
Clean Up
- Roll on second coat. Touch up missed spots.
- Let cure fully 72 hours before washing or exposing to weather.
- Clean brushes and tools with water.
Signs You Need Professional Stucco Repair
While many stucco issues can be addressed with DIY methods, extensive damage or signs of structural problems require a professional’s expertise:
- Large wall areas where stucco is crumbling away or detached from the substrate
- Bulging, hollow, or blistering sections indicating serious moisture issues
- Vertical cracks wider than 1⁄4 inch or showing substrate separation
- Diagonal cracks or stair-step cracks, which may indicate structural problems
- Damage extending across multiple walls or building corners
- Signs of rust, efflorescence, or extensive water staining on interior walls
- Inability to match existing stucco texture or finish characteristics
A licensed contractor who specializes in stucco repair has the skills to diagnose underlying causes, match your home’s stucco style, and properly integrate patches on difficult to reach areas. Thorough repairs help maintain the beauty and structural integrity of your stucco building.
Frequently Asked Questions About Repairing Stucco
How long does stucco patch take to cure?
Allow 24-48 hours for stucco patches to fully cure before finishing or applying paint or other coatings. Smaller thin patches may cure faster.
What causes cracks in stucco walls?
Cracks often result from normal expansion and contraction of the building materials. Structural issues like settling foundations, improper installation, or impact damage can also cause stucco cracks.
Can I use concrete patch for stucco repair?
Concrete patching compound is not a good substitute. Use a stucco-specific patch containing Portland cement and a polymeric binder. This matches the composition and texture of existing stucco.
What is the best stucco repair product?
Look for an acrylic-based stucco patch designed for vertical concrete and masonry repairs. Products like Quikrete Stucco Patch or DAP Stucco Patch have optimal workability and adhesion.
How long does stucco paint last?
High quality exterior stucco paints can last 3-7 years before needing touch up. Factors like weather, sun exposure, and surface preparation impact durability. Re-apply every 5-7 years for best results.
Conclusion
With routine inspection and proper maintenance repairs, stucco can retain its aesthetic and protective qualities for decades. Catching problems early allows for simpler DIY repairs. Use the right materials and techniques outlined here to fix cracks, patches, discoloration, and other minor stucco damage. For extensive deterioration or signs of underlying structural failure, contact a stucco repair contractor to fully restore your home’s exterior. Addressing stucco issues promptly extends the life of the finish and your entire house.