Imagine this scenario… You just built or remodeled your home and you went with a beautiful stucco finish on the exterior. The neighbors are complimenting you on your home, every day you drive home from work admiring the great looking stucco you just had installed… until that fateful day you start noticing cracks all over your gorgeous stucco! So, how did this happen? What can you do to avoid it?
Read on and you’ll discover that it’s not so difficult to keep your stucco from getting major cracks. In fact, if you follow my advice, you should avoid over 90% of the small hairline cracks that eventually show up in your stucco.
What is stucco?
Like sidewalks, driveways, and in most cases, your home’s foundation, the stucco on your house is made of Portland cement. Popularized by the Romans, cement has been a preferred construction material for centuries because it is a strong, long-lasting material.
Modern stucco is usually a mix of sand, Portland cement, lime and water, but may also consist of a proprietary mix of additives — including fibers and synthetic acrylics that add strength and flexibility.
What causes stucco to crack?
Despite its durability, even stucco is susceptible to cracks as weather conditions, climate changes and shifts in the home’s foundation cause it to expand and contract over time. Here in the Cortez and 4 Corners area especially, the extreme changes in temperature can wreak havoc on your home’s beautiful stucco exterior.
In addition, human errors can lead to cracks. Common mistakes include improper curing, incorrect installation and faulty workmanship. Obviously, it pays to hire a trusted professional.
How to avoid cracks in your stucco
Typically, stucco cracks show up in the corners, windows and doors, large areas of stucco walls, and above the foundation. Even so, builders can ward against these potential problems by taking the steps necessary to relieve stress on stucco exteriors.
If you’re building a home or remodeling and would like a great stucco look on the exterior with as few cracks as possible (I’m not going to say “crack-free” because we are talking about a cement-based product after all), then there are two simple steps you need to take…
- Buy a quality stucco system product.
- Hire a professional stucco installer that knows what they’re doing.
Buying a quality stucco product will give your installer some margin for error and hiring a trusted professional means they will know all the “tricks of the trade” when installing your stucco.
How to install stucco
Modern synthetic stucco can be applied as one base layer and a finish layer, which is thinner and faster to apply, compared to the traditional application of three-coat stucco.
As with any cement-based material, stucco must be reinforced to resist movement and cracking. Plastic or wire mesh lath, attached with nails or screws to the structural framing, is embedded into the base coat to provide stiffening for the stucco.
One method often used to help conceal the smaller surface cracks that may appear is the application of one of a variety of pre-mixed acrylic finishes. Flexible acrylic finishes have the ability to stretch and bridge over cracks, improving appearance and limiting the passage of moisture behind the stucco.
What stucco system should you use?
If you were to ask me to recommend a package of stucco products that will give you the greatest chance at a crack-free wall, I would go with Omega stucco products. Here is the combination I recommend in most cases…
- The Diamond Wall One Coat System from Omega Products: Go with the Diamond Wall Concentrate and mix sand separately. You can buy Diamond Wall with sand pre-mixed in it, but it can be more expensive than simply mixing the basic ingredients yourself. (It’s important to have the right kind of sand, however. The best type of sand to use for mixing stucco is plaster sand. This type is coarser than masonry sand and adds a heavier consistency to the material. You can buy Omega Products sand separately and still save money this way.)
- Akroflex Finish from Omega Products: This is a 100% acrylic-based finish, which adds strength and flexibility, helping to avoid many cracks that a non-acrylic based finish wouldn’t. There are several Akroflex options to choose from, depending on the textured look you’re going for (smooth, semi-smooth, rough, etc.). This results from the different aggregates each product option has embedded into the mixture. (Of course, the application method plays a big role in the finished look, as well.)
An added step that will eliminate 90+% of hairline cracks
Another product and step I would recommend in the installation of the Diamond Wall stucco system is to embed a reinforcing mesh just below the surface of the base coat prior to applying the finish. When properly installed, this mesh reinforces the stucco and helps to reduce the appearance of cracks.
With stucco cracking continuing to be one of the most common complaints from building owners, this is a cost effective way to eliminate the appearance of 90+% of hairline cracks that drive homeowners crazy.
Plus, using the products I mentioned above in combination will get you a 7 year warranty from Omega Products… and adding the reinforcing mesh to the base coat will add another 3 years to the warranty, giving you a total of 10 years of warranty on your stucco. (Make sure your contractor is an “Omega Products Approved Contractor”.)
Other materials you’ll need
In addition to your stucco system products, other common materials you’ll need include…
- 2 Ply Paper: Provides a layer of separation from your framing and sheathing (OSB, for example)
- 1” EPS (Expanded Polystyrene): Adds a layer of insulation and 4.17 per square inch of “R Value”, which measures the efficiency of your insulation.
- 20 Gage Stucco Netting (Lath): Metal lath provides the structural support necessary to hold the weight of stucco siding to a vertical surface. The lath has tiny openings that the stucco fills in, creating “keys.” Once the stucco dries in the lath, a solid base for the stucco walls forms. Metal lath helps to create a uniformly flat surface for stucco installation, as well.
- Weep Screed: A weep screed is a type of building material used along the base of an exterior stucco wall. Without a weep screed in place, water that is absorbed through a stucco wall would become trapped within the structure, leading to potential problems with rot and mold. The screed serves as a vent so that the moisture can escape the stucco wall finish just above the foundation. These devices are generally only used on walls constructed with wood framing, and are not needed on stucco-coated masonry structures.
- Bull Nosed Stucco Corner: A stucco corner bullnose is basically a piece of stucco mesh formed into a corner shape to make application easier, since getting stucco mesh to fit close to corners yourself can be difficult.
- Sheet Foam for Popouts: A stucco popout is when the stucco “pops out” from the rest of the stucco wall. You’ll usually see this around windows, doors, above stone veneer wainscoating, etc.
- Door & Window Tape: This tape goes around windows and doors to help prevent water from leaking in.
Other installation techniques to prevent stucco from cracking
- Install a 1/8” Gap Between Sheathing: Although it isn’t often done, it is actually recommended that builders leave a 1/8” gap between their sheathing to allow for expansion and contraction. If this isn’t done, the sheathing may bow out in summer, which may cause your stucco to crack. Besides installing it this way, another method to achieve this would be to run a circular saw down the seam set at 7/16ths deep after the sheathing has been installed. Most saw blades are about 1/8” thick, so problem solved.
- Install Control Joints: Builders can install a gap, called a control joint, between two stucco areas to ensure any cracks that occur do so in a way that does not deter from the appearance of the home. Control joints are best for large areas that exceed 144 square feet and help diminish cracks that result from expansion and contraction.
- Install Casing Beads: Casing beads separate stucco from other exterior materials on the home, such as wood and vinyl. Also called “plaster stops” and “stop beads”, casing beads act as a stop between dissimilar materials to reinforce vulnerable stucco areas and to prevent them from cracking. In addition, casing beads also create a stronger bond for the stucco on the wall.
- Install Corner Beads: Made of either metal or flexible plastic mesh, corner beads go along the corner of two stucco walls to reinforce stucco corners. Corner beads form a mechanical bond and create a strong, solid corner between the walls, which will relieve stress that might lead to unsightly cracks.
- Install Weep Screeds: Weep screeds, which should be installed about 8 inches above the home’s foundation, control stucco cracks because they keep water draining out and away from the house, which will prevent moisture damage. They also help to avoid inconsistency in the stucco’s thickness that could lead to various stresses and cause cracks.
- Install Soffit Drip Screeds: Soffit drip screeds prevent water from draining down the fascia, the horizontal surface that runs along the top of columns or walls of the home, and back to the soffit, the underside of the home’s construction such as under either an arch or a ceiling. This helps prevent cracks by keeping water that runs down the exterior of your home from returning to the soffit and creating moisture damage.
- Wet Curing Your Stucco: Stucco must be properly cured to promote adequate bonding between the cement and the aggregate particles of the stucco as well as adhesion to the underlying structure. The curing process entails maintaining proper hydration and temperature of the stucco coat. Hydration is affected by variables including air temperature, humidity, wind and sunlight. As a rule of thumb, your stucco’s base coat needs “wet curing” for at least three days, two to four times per day. Wet curing is as simple as taking a hose and wetting the outside of the stucco down, which allows the entire stucco layer to cure more evenly and consistently.
Hiring a stucco contractor
A stucco contractor should be skilled at mixing and applying the stucco to ensure it withstands weather conditions and time. They will also make sure that the tinting in the stucco is correct so that it dries to the color you are expecting. Stucco contractors should be able to work on a brand new home or business, applying stucco to the building exterior. They should also be able to work on older homes, refinishing the exterior.
We have a list of stucco contractors in the Cortez area on our website. Click here to view the list and get their contact information. Contact them to find someone you feel comfortable with. Another great way to find a good a good stucco contractor is to ask friends, family, and neighbors who they’ve used and what their experience was like. Good luck on your stucco project — hopefully this article helped give you a good idea of what to do to avoid cracks and have a stress free experience.
Derek Alvarez sells stucco products and building materials at ProBuild here in Cortez, Colorado. If you have any questions for Derek, you can contact him at 970-739-9911. *The views and opinions expressed are those of Derek Alvarez alone and do not necessarily represent the views of ProBuild.