Need advice on sealing Stucco cracks caused by expanded wet rebar and mold, should I hire a Pro or DIY repair?
Asked by Uglješa Milovanović 
4 months ago
Last Updated: September 3, 2024
What’s the top method for fixing Stucco cracks? The rebar got wet and expanded, leading to this issue. It even caused some mold, so I’m planning to bring in professionals to handle the interior mold removal. I’ve worked with drywall before and feel pretty confident I can take care of the cracks myself, unless there’s a good reason to call in the pros instead.
You might want to leave it to the professionals if you mentioned rebar in stucco. It seems more like water damage from the inside. Save yourself some money and hire the pros.
Just so you know, there isn’t any rebar in stucco. And, rebar doesn’t expand.
Hey there,
It appears that someone backed a U-Haul truck into that area, causing approximately a 1 1/2″ gap in the stucco above. The stucco seems to be more severely damaged closer to the house. Just a guess, but I wish you good luck.
Stucco doesn’t incorporate rebar and is only 3/4″ thick. Not sure where the confusion is coming from.
Just to clarify, it’s wire lath that’s deteriorating, not rebar. This particular structure has stucco applied over plywood sheathing.
Hey , it actually appears to be more like EIFS than traditional stucco. I can definitely see the styrofoam in there.
Hey , that’s the vapor retarder. They use Tyvek or a similar house wrap. The first story is made of block, while the second story is stick built and sheathed with plywood or OSB.
Stucco serves as exterior plaster over metal lath…. over time, the lath may deteriorate and weaken… you may need to chip out those sections and possibly replace parts of the lath for a proper fix. Best of luck.
This is a common issue. The second floor has a wooden frame. The stucco is applied over wood lath and plywood sheathing. Considering the extent of the damage, it would be best to hire a contractor to remove the affected stucco and lath area. Repair the sheathing and flashing, then reapply a PM stucco that can accommodate expansion during daytime heating cycles.
In stucco, there’s no rebar. The wire mesh is of a small enough gauge that corrosion shouldn’t stress the stucco. The cracks and spalls are likely due to water getting trapped at the base and freezing during cold periods.
I’d suggest using a masonry blade to cut out the damaged area above the cracks, then remove the damaged stucco, inspect the metal lathe, and replace any rusted parts before re-stuccoing.
I’ll always wonder why people in cold, wet climates choose to use stucco. It was originally designed for dry, hot climates.
What about rebar? Stucco has a lattice similar to chicken wire. I’ve never seen it expand from getting wet, although stucco can deteriorate from prolonged exposure to water. The lattice is usually in the undercoat, and it’s typically the top coat layer that deteriorates – especially around sprinklers and areas where water pools.