Stucco 101

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Stucco walls have been common in hotter climates for centuries. Today, stucco is increasingly popular all over the world—a great way to add a finished, Spanish flair to exterior surfaces, covering unsightly, bare cement or concrete blocks.

A Brief History of Stucco

Stucco gained popularity as a siding material in North America during the 20th century, but it's been around for hundreds, if not thousands, of years. Modern stucco is a hard-setting plaster made from a combination of cement, water, sand, and lime. The ancient Greeks and Romans used stucco walls made from gypsum, marble dust, and glue as a base for their beautiful wall frescoes.

While stucco is now rarely used for art, it has a number of practical features that make it an appealing choice for home siding. Stucco is hard, it resists water, it's excellent at blocking wind and providing insulation, and it requires very little maintenance over its lifetime. Best of all, stucco can be installed by a DIYer willing to take some time to create a long-lasting exterior for their home.

Synthetic Stucco

Synthetic stucco has the same look as traditional stucco, and can even be more flexible from a decorative standpoint, but it's made up of layers including foam board, wire mesh, and acrylic paint. As a result, it admits very little air or water flow, making it better as insulation, but counter-intuitively worse as a defense against weather. If water finds a way behind synthetic stucco, for example, it can cause mold and rot on the interior surface. Synthetic stucco can be as durable as traditional stucco but does requires a little more maintenance.

blue stucco wall

Sustainable Stucco

A focus on the environment has brought many new innovative designs in green building. One of these is using straw bales in the construction of stucco homes. The concept has actually been around for over a century but has recently gained a new focus. The idea is that the stucco cement is placed on stacked bales of straw instead of the traditional metal wire. This makes the construction faster and more energy-efficient, and it uses a completely renewable source.

Installing Traditional Stucco

Installing stucco is a time-consuming process. First, the walls need to be prepared, and then the stucco itself is installed in three stages: a scratch coat, a brown coat, and a finish coat.

When applying stucco to a wooden wall, the first step is to cover the entire wall, either with 15-pound roofing felt or plastic house wrap, and tack the material firmly in place (to prevent moisture from getting into the wall). Over that, add a layer of 17-gauge, galvanized wire mesh. On concrete or brick walls, the first step is spreading a concrete bonding agent over the entire wall surface and giving it time to dry.

Once the walls are prepped, the next step is to apply the "scratch coat." This is a 1/4 to 1/2 inch-thick layer of mortar spread with a mason’s trowel. The mortar needs to be pushed down firmly into the wire mesh on wooden walls to provide a solid base for the rest of the stucco layers. After the scratch coat is applied, it needs to be allowed to partially dry for a few hours. Use a "plasterer's rake" or a sharp piece of metal, scratch horizontal lines into the surface about 1/8 inch deep.

Stucco needs to dry slowly. The scratch coat should be left for a day or two. During this process, occasionally mist it with water to prevent it from drying too quickly.

Once the scratch layer has dried, it's time to apply the "brown," or leveling, coat. This is a stucco layer applied directly to the scratch layer, then "floated" to create a smooth, even surface for the final coat. Once again, you need to allow the brown coat sufficient time to dry thoroughly before applying the finish coat.

The final coat is laid over the brown coat approximately 1/8" to 1/4" thick, then leveled with a finishing trowel. In the finishing layer, you can add colored pigments to give the wall a different color.

After applying the finish coat, allow it to dry slowly, again misting it occasionally to prevent possible cracking.

hand brushing a wall

Maintaining Stucco Walls

The most important method for caring for any type of stucco is to periodically clean the stucco surface. You can easily wash the area clean with a garden hose and mild soap whenever needed.

Starting at the bottom of the wall, saturate the entire area with water until you get to the top, then keep a steady stream of water focused under the roof to dislodge dirt and debris. As dirt runs down, maintain that flow across the top until all the dirt is washed away.

Once the area is clean, inspect the wall for any damages or cracks. If any are found, they can easily be repaired with caulk or stucco mixture. Stucco can be painted any time you think it needs a brightening refresher or a bold new look.

Stucco Application

For the best results, it helps to know some minor tricks. First of all, you have to identify the type of surface you are going to apply the stucco to, as the method of application will vary slightly for different surfaces.

Concrete Wall

When applying stucco to a concrete or brick wall, you must first apply a bonding agent to the wall and leave it to dry completely. Once that has dried, apply the stucco directly onto the wall, starting first with a scratch coat of around a 1/4- to 1/2-inch layer of stucco. Once the stucco is slightly hardened, scratch it to a depth of 1/8 inches and leave it to harden and dry completely for the next 36 hours, misting the surface occasionally to keep it moist.

Wooden Wall

When it comes to applying stucco to a wooden wall, the wall needs a different preparation from what a concrete wall requires. First you have to attach a 15-pound roofing felt over the wall and then cover it with a 17-gauge metal netting. Once everything is in place, you can apply a scratch coat made of a 1/4- to 1/2-inch layer of stucco, making sure to force the stucco into the netting. As with concrete walls, once the stucco is slightly hardened, you scratch it to a depth of 1/8 inches and leave it to harden for around 36 hours. Remember to mist the wall periodically to keep the stucco moist.

Mixture Preparation

One simple trick in getting a very good stucco finish is in the mixture preparation. If the stucco mixture is prepared by an experienced person, the consistency of the mixture will always be the same, thus saving time and quickening the process of stucco application. When the stucco is not always consistent, every time you have to apply a new batch, you need to work at the new consistency through trial and error until you get the desired finishing effect to continue from the already applied stucco from the previous batch.

Crack Formation

Cracks do not happen for no reason. When a crack forms, it is normally the result of bad workmanship. The most common problems are that the wrong amount of water was used during the mixture preparation, the wall was not kept damp enough during the 36 hours of hardening, or else the second coat was applied too quickly over the first coat without giving the former the appropriate time to dry and harden as required. Cracks are not easily fixed, and therefore, they must be avoided as much as possible.

Maintenance

Stucco applications normally last for years and even decades if they are applied correctly and inspected for any signs of damage or wearing off every year. First wash the wall well from any dirt to reveal the surface and check for any signs of damage. Particular attention much be taken when checking the areas where the stucco joins another surface, such as around a window. Make sure that areas around windows, doors or other surfaces are still well sealed and that no openings that might allow water to seep through and underneath the stucco are present.

Stucco Textures and Styles

With the right stucco texture, your home can stand out as the neighborhood showpiece. Many people have been using stucco to side the exterior of their home for many years because of the durability of the product. It is widespread in its use, but can be mostly found in the southern and western parts of the country. Stucco is a mainly a Portland Cement product that is very cost effective and versatile.

Before slapping some stucco onto the exterior of your home, take time time to consider the texture and color you'll be adding to the mix. Using some different aggregates in the cement mixture homeowners can choose from a wide range of colors for their home's exterior. Different textures give the stucco great depth and character.

Stucco texture is achieved through choosing different-sized aggregate and controlling the way that it is mixed. With the right combination the texture of your home can resemble a wood finish, brick, and other masonry. There are several different types of stucco texture to choose from.

Deep Relief Stucco

This is perhaps the most popular style of stucco texture. This has a broken up appearance that gives the exterior of the home great depth and character. It is applied without any uniformity in the trowel strokes, depth of creases, or with any type of organization. The Deep Relief stucco texture is the easiest to apply, especially for do it yourselfers.

Rock and Roll Stucco

Somewhat resembling a popcorn ceiling, this type of stucco texture is basically a layer of stucco with a brushed look. Applying this type of texture is done through either a trowel and a stiff brush, or it can be blown on with a special sprayer. It has a great look to it, but can be a little overwhelming on a large surface. The Rock and Roll stucco texture does look great on retaining walls, solid concrete boundary fence, and outbuildings.

Trowel Sweep Stucco

This design looks exactly like the name implies. There are raised lines in the stucco made by pressing one end of the trowel a little deeper into the stucco than another end. It is a more organized look than the Deep Relief texture and goes from top to bottom. Each of the "sweeps" are in their own line. Trowel Sweep stucco texture is one that is best used with a colored pigment rather than a bright white.

Frieze Stucco

If you have ever seen an aerial photo of Antarctica, you've seen what the Frieze stucco texture looks like. This type of texture is a mix of both flat surface and relief surfaces. The relief area is mostly the same height as the flat so there is not a lot of depth, but there is plenty of character. This texture is created with the use of different application techniques with flat trowels and sponges.