Over the years, stucco has become a very familiar and popular choice for finishing the exterior of homes throughout our region. Stucco can last the lifetime of a home if properly maintained and cared for. It has long been a very common misconception that stucco is a relatively maintenance-free finish. Unfortunately, this is typically not the case for several reasons.
Stucco is extremely porous, and will absorb rain and moisture very easily. This can cause deterioration, unsightly mildew, moss and mold growth and cracking during freeze-thaw weather conditions. (Cracking happens when the moisture that the stucco absorbed expands as it freezes.)
stucco cracking can also be caused by general settlement of new homes. Of course, when cracking occurs, this allows more moisture penetration, and can only exacerbate the problem. In severe cases, stucco can actually “bow”, or pull from the surface. As well, when stucco wicks moisture, this can cause rotting of adjacent wood surfaces such as Tudor trim, window frames and doorframes. The moisture enters the backside of the wood and causes rotting from the inside out.
By performing some maintenance, these problems can be avoided and the life of stucco greatly increases.
Stucco can and should be sealed properly to prevent moisture intrusion. If new, stucco can be sealed with a clear concrete/ masonry sealer, which will penetrate into the stucco and stop moisture entrance. These are typically silicone type sealers. While effective, these finishes will usually need to be redone every 4-5 years.
If the stucco is older and has already developed cracking, an elastomeric coating would be a best choice. These finishes are waterproof, seal hairline cracks, and are extremely pliable and flexible. If cracks develop below these coatings, the finish will stretch and bridge the crack, and help keep waterproof. As importantly, these finishes are microporous; they will breath to allow moisture vapor behind it to properly escape without bubbling and blistering. When properly done, elastomeric coatings can easily last 10 or more years.