EIFS in the South
I moved to Florida a few years ago. Construction is different down here. If you live in the southern states or do a job there, here are some insights to the many differences between design and installing EIFS in the South vs. the rest of the nation.
First, it’s hot and humid during the summer. This affects the design and construction of exterior walls. The following are some affects of the weather.
EIFS finishes set up by drying (the evaporation of water). Finishes take longer to dry when it’s humid. Some EIFS basecoats also set up by evaporation of water. This applies to the cement-less type. The basecoats that use Portland cement are not affected so much by humidity.
YEAR ROUND CONSTRUCTION
The construction season is year round. An exception is the mountain areas in the South. This includes the Appalachian, Smokies and Blue Ridge mountains. Most of the South rarely gets cold or snowy weather. However, the transition climate areas can be a problem. These areas—usually at higher altitudes—have swings in temperature that can make it necessary to provide temporary protection to avoid the cold from freezing wet EIFS materials.
Much of the coastal area in the South is low lying. If a hurricane strikes, the tidal surge can send water far inland. This is what happened when Katrina struck New Orleans. This part of the South is called “The Low Country” and is full of inlets and marshes, and towns that are not far above sea level.
The low-lying nature of the land also makes inland areas subject to flooding due to heavy rain. Roads can flood and a building’s first floor can be inundated with water, because the water has nowhere to go. The water lays on the land and quickly spreads sideways in populated areas. In all, this means that EIFS should be kept above grade and attached to a substrate that is not water sensitive.
The southern U.S. coast is known for its hurricanes. They tend to stick to the coast—both the Gulf of Mexico and southern Atlantic. It goes without saying that exterior walls need to be designed to take hurricane force winds. The intensity of the wind varies with the building’s height and location. The taller the building, the higher the force at the top. Wind forces are also greater at the corners of buildings. Don’t forget that hurricane forces can also occur during the construction process and this needs to be taken into account if the exterior walls are constructed during hurricane season, when the walls may be exposed to wind forces from both sides at once.
The South, like the central Midwest, gets tornadoes. The worst ones move from west to east through Mississippi, Arkansas and Georgia. Sometimes, they show up in northern Florida. Unlike hurricanes, tornadoes can appear with little notice. During construction they need to be taken into account.
Central Florida is known for fierce lightning storms. They usually show up in the afternoon. Buildings need lighting protection (not just EIFS buildings) to avoid property damage and injury.
Following my comments earlier, you should be aware that the dominant building code in south Florida comes from Miami. It is the Dade County code. But the Dade County code is used in many areas outside Florida. In particular, the Dade County code has special, extensive requirements for hurricanes, a weather system that can affect not only Florida but also the East Coast and the Gulf Coast. Dade County’s code has more demanding requirements for performance of exterior walls in hurricanes. This includes testing which entails the penetration of wind borne objects that might go through a wall. Many EIFS producers offer special versions of their systems which can pass these tests.
Termites can be a major problem in the South. The building codes recognize this and require the bottom edge of the wall to be held at least 6 inches above grade, sometimes more. Although it looks nice, you do not want to bury the bottom edge of an EIFS wall in the ground. The dampness will deteriorate the EIFS, and give a path for termites and other crawly things into the wall. This is one of the reasons why the first floor of many buildings is masonry.
WATER AND VAPOR CONDENSATION
Due to its hot, humid summer weather, buildings in the South can have a unique problem. It concerns the water vapor (a gas) in the outside air. The vapor tries to move through the wall toward the cool, air conditioned indoors. EIFS coatings are semi-vapor permeable and allow some water vapor to pass through them. This is fine, except when the inside of the wall is not vapor permeable. The problem is this: The water vapor can condense on the outdoor side of the interior finish. An example of this can be drywall with a vinyl wall covering. This condensation can trap moisture in the wall, leading to deterioration and sometimes mold and mildew, or rusting of metal studs. This problem is real and has frustrated building owners of structures such as hospitals and hotels. What’s the solution?
The solution is to use a vapor permeable interior finish. This can be a problem in certain forms of exterior wall construction, such as the common stud cavity form of a wall design. Sometimes, a waterproof and easily cleanable interior surface is needed. Materials such as tile and sheet vinyl are not permeable. Luckily, it doesn’t take much to let the vapor pass harmlessly to the building’s interior. Just a few small openings are enough to let the vapor bypass the interior finish.
The South has woodpeckers. They migrate and when in an area with an EIFS building, they will auger through the EIFS lamina and dig out the insulation. They then make a nest, and are hard to get rid of. Killing them is not allowed as some species are considered endangered.
As you can see, architecture and construction using EIFS is a bit different in the South. The same is true for other professions, such as medicine and architecture elsewhere in the country. These jobs tend to be regional in nature and need local licensing and adherence to local building conventions. So if you are selling or installing EIFS in the South, keep the above basic concepts in mind. W&C