REPAIRING CRACKS IN STUCCO WITH AN ACRYLIC FINISH
When stucco cracks are excessive and/or unsightly and it is derided that repair is desired, there are alternatives. The method of repair will depend on the type of cracks (cause), amount cracking, existing finish, desired outcome, stage of construction and economics. All these repair options are assuming the stucco system is sound and well attached to the substrate.
- Touching up a hairiine crack with the same material from the existing colored finish material will generally be the least expensive option and is best done by lightly clapping the crack with a stiff brush using the same finish material. However, this repair can be more unsightly than the original hairiine crack. Re-coating the entire area from an architectural break to another architectural break will produce better results than merely addressing the crack area. If the source of stress is a one-time event, the crack will not reappear. This is usually a repair procedure for "shrinkage cracks".
- Painting a building for a color change is a good time to repair cracks. A knife grade elastomeric, caulk or non-shrinking cement are all possible patch materials prior to painting. The light reflective value of the existing stucco and new paint will have a determination as to the best patch material. Test panels are strongly recommended prior to starting the entire building. 100 acrylic paints that are vapor permeable are recommended for re-painting. It is possible to recoat the entire surface with an elastomeric type coating or paint. Elastomerics will stretch and bridge minor cracks. Elastomerics must be applied to manufacturers recommended mil thickness to work property. Elastomerics should not be used to solve water intrusion problems and future re-coating concerns should be discussed. Most of the elastomeric type coatings have a distinct mat type look and can change the look (texture) of a building. Another concern is the vapor permeability and condensation.
- Re-coating the area with the same finish coat from architectural break to break is also possible solution. The new re-coated area will have a slight change in tone of color due to the double thickness of finish. If the cracks are structural in nature, the will most likely reappear.
- A non-cementitious base coat (NCB) can be trowel applied over an existing acrylic finish. Strips of reinforcing mesh can be troweled into the basecoat over the crack to provide additional reinforcement against future stress. The surface would then be re-coated with an acrylic finish coat. A test patch must be made to insure proper bonding to any existing stucco surface. A method to cover a stucco wall that has excessive cracks and additional protection against stress is desired is to trowel the reinforcing mesh (4 to 6 oz. per square yard) into the basecoat over the entire wall surface, making sure to over lap the mesh by 2 inches. This lamina is strong, yet flexible and vapor permeable. The stucco surface should not have a texture as the maximum build up with the non-cement basecoat is typically limited to 1/8 to 3/16 of an inch. A slight inherent buildup can be feathered down at control joints and other terminations. The existing stucco surface should be dean prior to recoating. All manufacturer recommendations should be followed.