… that is a statement not a noun. Out here in the desert, all new homes are being built with a stucco exterior. Stucco is made of concrete, chicken wire and styrofoam, which makes it strong, lasting and cost effective. But by its very nature, stucco is going to crack. Whether it’s due to the foundation settling, repeated hot/cold cycles or any number of reasons; homeowners want to repair them. There are many ways to repair cracks in stucco and this can be as helpful as it is hurtful for the novice/diy painter. The rule of thumb for repairing cracks is start small. Using a one size fits all approach to repairing cracks will leave the exterior of your home looking like a shoots and ladder board.
The most common mistake for diy’ers is to think all cracks are the same. This thinking causes them to over do it, insert your sledgehammer and fly analogy here. The smallest cracks in stucco, typically less than 1/16th of an inch wide or about the thickness of a dime, are purely cosmetic and should therefore be addressed cosmetically and not functionally. The best way do this is to begin with a 100% acrylic paint or primer. Acrylic paint has the property of elasticity which allows it to bridge over small distances to stay ‘in contact’ with itself. This will allows your paint to fill the cracks and smooth the surface at the micron level, making it look as if it never existed. The best way to start is to apply the paint in a spray application, just at you would if there were no cracks. Using a cross hatch pattern and applying two coats should take care of any hairline cracks on the outside of your home. For stubborn hairline cracks a back roll application will apply a thicker coat of paint and fill in the remaining space. For sand stucco you can back roll as a spot application but for spanish lace and other aggressive textures you will want to back roll for an entire wall to ensure the back roll doesn’t affect the profile of the texture. For hairline cracks on vertical surfaces (walls) avoid using elastomeric primers. Elastomerics do not breathe and will trap water, causing those areas to bubble and eventually peel. Elastomeric primers should only be used to ‘top’ parapets where gravity can draw the water away.
After you’ve tried an acrylic primer and back rolling, the next step is to patch the individual cracks. The first type of stucco patch to try is an elastomeric patch. This is different from an elastomeric primer. The primer is a liquid which creates an sheet over the stucco while the patch is a solid filling. Talk with a professional at your local hardware store to find a reliable and lasting product. Elastomeric patching comes in two varieties, textured and non textured (knife grade). Depending on the texture of your home, each has a purpose. When using patching material, less is more. Any patching material you put on the outside of your home is going to change the profile of the stucco. This is due to excess patching sitting a top the existing stucco and changing the texture. When light reflects off of this extra material it stands out and the amount of material directly relates to how much it stands out. The noticeable patches are commonly referred to as ‘snakes’.
When cracks get to be over a 1/4″ wide or you have exposed styrofoam, its time to move to a concrete based patch. This form of patching is the most complicated and many times requires a professional to apply it. While an elastomeric patch can fix this category of cracking in the short term, it will not stand up in the long term. There is good news! This patching technique tends to be less visible than elastomeric patching if done correctly. Concrete stucco patching has the same properties as the existing stucco and can be applied in a similar texture.
Remember most cracks are cosmetic, so use a process which is aesthetically pleasing.
Consult with a professional house painter in Phoenix to determine which type of primer or patch will be most appropriate for your project.
With stucco, I think it’s important that you take care of the cracks as soon as you notice them. No sense in ignoring them and having them get worse over time. I do like how you mentioned that most of the smaller cracks are purely cosmetic, so you don’t need to tear down the wall to fix those.