House exteriors are composed of many layers that work in conjunction with each other. The most visible layer and the one most important to the house’s lifespan is the outermost layer: the siding or cladding.
The most popular types of house siding are fiber-cement panels, vinyl siding, and plywood. But there is another form of siding that has been used on houses for centuries and which still continues to serve houses well.
This siding is called stucco finish. Unlike other types of house finishes, it applies equally well over both masonry and wood-sheathed homes (though with a few modifications for wood-sheathed homes).
Sheathing is the material used to cover the floor, wall, and roof framing of a structure. Wood-sheathed homes have sheets of wood products forming the exterior walls, which then can be covered with siding. House wrap and exterior insulation are often placed between the sheathing and the siding.
What Is a Stucco Finish?
Stucco itself is a cement-type mixture made of sand, Portland cement, lime, and water. Stucco is considered a thin finish coat, the outermost layer that is visible and can be painted.
To make stucco work, you need layers below it to provide an adequate base. Today, it is not necessary to mix stucco from raw ingredients. You can buy pre-mixed stucco finish at most home centers that require only the addition of water.
Stucco Finish Advantages
Stucco is often tinted to add color, rather than painted, ensuring colorfastness. At the same time, stucco can be painted with ordinary exterior house paint.
Because stucco is worked by hand, it can be textured in any number of ways. Because of this, stucco lends itself well to creative embellishments.
Stucco is considered one of the cheaper types of siding because it does not use expensive materials. While most stucco finishes are created from mixes, it is possible to make your own stucco finish from raw ingredients.
Stucco house finish provides an excellent seal against rain and snow because, unlike nearly every other form on siding, it is seamless. Seams promote water- and air-flow into a home. Even seams that appear to be well-sealed may eventually open up.
Stucco Finish Disadvantages
Stucco’s root word, the Italian stucchi, meaning crust, fragment, or piece truly comes into play whenever stucco is accidentally hit with a lawnmower or scraped by even a small tree branch. Stucco can be damaged quite easily. When damaged, its crust will flake off.
To repair other types of siding, such as vinyl siding, the damaged panel is replaced by an intact panel. For a stucco-finished house, though, the stucco must be mixed up and applied with a trowel, after which it should be left to cure for at least a full day. To match colors, it is often easiest for homeowners to call a repair service than to undertake the repair by themselves.
Stucco finishes most often are professionally installed. Do-it-yourself application for small areas is possible but whole-house stucco finishing is not recommended.
While it is true that stucco can last for 50 years or more, it does require proper maintenance to meet that lifespan.
While stucco materials are inexpensive, the total project cost may still be high because much of the cost of a stucco finish is dedicated to time-intensive labor.
Stucco Finish Layers
One prime place to install a stucco finish is over concrete masonry. Concrete masonry is stable and less prone to expansion and contraction and other movements that may crack the stucco. While stucco finish can be applied to a wood-sheathed home, additional reinforcement is needed.
Stucco on Masonry
On concrete masonry, little more than a scratch coat is needed below the stucco finish. A scratch coat is a base layer of cementitious material that is literally scratched horizontally with a comb-like tool.
Stucco on Wood
Wood-sheathed buildings require more preparation for a stucco finish than do masonry buildings.
Wood sheathing itself will not provide a proper base for a stucco finish. You need to layer it with a house wrap or other waterproof building paper and then with self-furring metal lath. This lath provides the grip for the scratch coat to hang onto.
After the scratch coat, apply a brown coat to provide a smooth surface for the subsequent stucco finish.
The recommended thickness for the scratch coat for either masonry or wood-sheathed buildings is 3/8-inch minimum.
Can be textured as well as tinted
Low-cost compared to other styles of siding
Tight seal against weather
Long-lasting when well-maintained
Repair is not easy
Difficult for DIYers to install
Not appropriate for every locale
Easily chips and fragments
Source: The Spruce