What Determines the Thickness of Stucco?
The thickness of stucco is determined by two main factors: the type of stucco you have, and what material the stucco has been applied over. There are three different types of stucco that are commonly used:
- EFIS Synthetic Stucco: This synthetic material is more flexible than traditional stucco and contains a moisture barrier. The synthetic stucco is around 80% lighter than traditional stuccos due to the fiberglass that is included in the makeup of the material.
- Traditional Stucco: This material is formed from lime, sand and water and forms a cement barrier over the building materials.
- One Coat Stucco: A one coat system is a shorter stucco application process, and involves the application of a blend of Portland cement, sand, fibers, special proprietary chemicals, and water to the outside of a building or home.
Stucco can be applied to many building materials including wood or metal framed walls, concrete block surfaces, precast concrete surfaces and concrete poured in place surfaces. These different materials will affect the thickness requirements of the stucco, as well as the workmanship that the stucco is applied with.
What Is the Correct Thickness of Stucco?
As mentioned above, the type of stucco and the material stucco is applied over will all matter in determining the correct thickness of stucco. Additionally, the codes of stucco thickness vary from state to state, so be sure to confirm with your local [Phoenix stucco contractor](https://titanstuccoaz.com/) about state regulations to ensure that you are following local guidelines when applying stucco to your home. However, there are general guidelines that can be used as a reference for the different types of stucco and their required thickness:
EFIS Synthetic Stucco Thickness
EFIS, Exterior Insulation and Finish Systems, Synthetic Stucco is actually a wall assembly system that is designed to resemble traditional stucco siding. The outer finish of this siding is only required to be 1/16 of an inch thick. This layer includes a glass fiber reinforcement mesh that is embedded in a base coat and covered by a crack-resistant finish, which can also be decorative depending on homeowner preference.
When EFIS synthetic stucco is assembled with a foam board, a water barrier and a drain plane, the thickness will be different. The foam board can be as thin as 1 inch, but it can also be much thicker, if the contractor desires a higher insulation level for energy purposes. Building codes usually limit the thickness of a foam board to around 4 inches, but typically the thicker foam boards will be on commercial buildings. For residential homes, you can estimate that the foam board will usually fall within the 1 to 1 ½ inch thickness range.
Traditional Hard Coat Stucco Thickness
Traditional hard coat stucco usually follows the thickness requirement of building codes, falling at around ⅞ inches thick. The most common type of stucco, the traditional hard coat is usually applied in 3 layers: A ⅜ inch scratch coat, a ⅜ inch brown coat and a ⅛ inch finish coat.
“One Coat” Stucco System Thickness
A one coat stucco system is a layered system using an engineered blend of cements applied over a rigid foam board using a metal wire lath. The one coat system varies in thickness requirements based on the manufacture of the stucco materials, and you should follow instructions laid out in the manufacturer’s guide for the best results. Typically, the one coat system will be between ⅜ to ½ inch thick.
Block/CMU Wall Stucco Thickness
If you apply stucco to a masonry wall, also known as a concrete or cinder block wall, the thickness of the siding is usually required to be ½ inch. This consists of a ⅜ inch scratch coat, with a ⅛ inch finish coat applied on top.
Why Does Stucco Thickness Matter?
Stucco thickness will affect the lifetime of the stucco: if it is applied too thick, it may crack, while if it is applied too thin the building materials under the stucco may show through, affecting the curb appeal and the durability of the siding.
Stucco Thickness Affects Strength
The thickness of the stucco also affects the strength: studies have shown that for traditional hard coat stucco, if the stucco layer was too thin, it can only withstand half the impact of the recommended ⅞ inch thickness. The thickness not only helps prevent moisture from breaking through the stucco, but it also provides a layer of protection from storms, strong winds, hurricanes and earthquakes.
Stucco Cracking Issues
If stucco is applied in too thin or too thick of layers, it can cause cracking issues. If the thickness of the stucco varies throughout the application, it will lead to greater cracking issues over time. When stucco cracks, it allows moisture to seep below the surface, causing deterioration to the stucco and the building materials of the home.
Fire Protection Reduction
Stucco that is applied in the recommended thickness will provide a layer of fire protection for your home. If the stucco is not as thick as it should be, it will be less resistant to any fires, this is especially important when the home is constructed with a wooden frame, which is extremely flammable.
Lathing Problems
Stucco that is overly thick can cause lathing problems, due to the unnecessary strain the extra weight puts on the lath. Lathing can begin to sag, or even fall off due to the thickness of stucco. This can cause structural damage to the siding, and even your home if the issue becomes severe.
Working with stucco can be a complicated process, and the thickness is an extremely important consideration to ensure your stucco stands the test of time and serves both the aesthetic and structural purpose you desire. Contact Titan Stucco today and speak with one of our seasoned stucco professionals to learn more about the importance of stucco thickness, and how our team can help you up your curb appeal and structural integrity with expertly installed stucco siding.
