Cosmetic Stucco RepairRandom cracking, for example, cracks that start at the corners of windows is considered normal. http://www.stuccomfgassoc.com/industry/papers/PlasterCouncil_tech4_crack.pdf Several things can be done to reduce the likelihood of cracking, such as hydrating the stucco by applying water during the summer if the surface is drying too quickly, or providing tenting and heating in the winter and letting the base coat completely cure before applying the stucco finish. Stucco manufactures spent millions of dollars for special engineers to design their stucco systems. These stucco systems were then subjected to accelerated weather testing, both by the manufacture and the International Code Council (ICC). Once these stucco systems passed the testing they were sold to the public. It was understood by the manufacturers, engineers, and the ICC that cement based stucco systems were not flexible and would crack from structural or thermal flexing or movement. Cracks in a stucco system shouldn’t be blamed for a leak. Contractors that sell repairs by fixing the cracks don’t understand how stucco systems were designed work. The building papers, the window, the roof, and other flashings behind the stucco system are what ultimately keep water from getting to the framing members and from coming into the home. Isolated cracking and staining are an indication that there is a problem. The simple act of covering the cracks with new stucco finish or paint will not fix the problem. These patches are only a temporary cosmetic solution that covers up the problem and the extra coating of stucco actually keeps the wall from drying out and accelerates the dry rotting of the 2x wood framing and plywood sheathing. Random cracking is a cosmetic problem, which can be fixed only by using the proper techniques to control the movement, painting or re-finishing the stucco without reinforcing the cracks will allow the cracks to telegraph through the paint or new stucco finish.
A stucco exterior over plywood sheathing, as is the case in most residential homes, should never be painted. The correct way to make cracked or damaged stucco look good is to re-coat it with similar materials to those that were original.
Even though new stucco cannot be matched to old exactly, peeling and flaking as shown above, can be successfully repaired properly.
In the wall to the left, the cracks have been covered with a fiberglass mesh and base coat material. In the photo above, a new “skim coat” bonding/leveling agent has been applied.
- Random cracking can be eliminated by applying a reinforcing mesh, embedded in a cementitious base coat, over the crack, apply a leveling coat to hide the crack reinforcement. A new stucco finish coat is then applied over the top of the repairs.
- Elastomeric or acrylic paints and stucco finish, applied over cracks in a stucco wall in an attempt to eliminate the crack will not work through a season in Utah’s freeze thaw climate. Without reinforcing the cracks they will telegraph through the new elastomeric or acrylic paint or stucco finish. Any guarantee given should be carefully inspected to see that it actually guarantee’s that cracks won’t telegraph through the new finish. “Lifetime guarantees” almost never apply to spanning cracks, or will exclude cracks if the warrantor can show that it was cause by structural movement, which is what causes cracks in the first place. Most “lifetime warranties” only cover the cost of new materials; the cost to apply the material usually isn’t included.
- Contractors that suggest fixing cracks in order “seal up the wall” to keep water from getting into your home are just trying to make a sale. It’s the secondary water management system behind stucco that ultimately keeps water from getting into your home.