EIFS vs. Stucco and switching over
Exterior Insulation Finishing Systems are often associated with or described as stucco-like. In many cases they look quite similar, and EIFS are referred to as “synthetic stucco”.
- Stucco is hard, and sounds solid when tapped.
- Stucco may look “swirled” or have other naturalistic looking patterns.
- Stucco is a cement-like application, generally placed over a metal lath, a thin strip of metal.
- Stucco is a generic product that comes in many different types.
- Stucco requires a substantial amount of joints used due to how it shrinks after being installed.
- When knocked on, EIFS sounds hollow and is softer to the touch.
- The textured top coat of EIFS is of a much finer finish than stucco.
- EIFS insulates buildings and homes.
- EIFS is a layered system involving several components: a cementitious base coat with reinforcing fiberglass mesh, insulating foam, and a finished, textured top coat.
- EIFS are systems made by different companies and are described by brand.
- EIFS requires very few joints in installation and can be used on a substrate that also uses little to no joints.
Even though from a distance both materials look very much the same, there are many important differences between the two, some of which may be surprising and should be factored in to any decision as to whether to switch over between materials. For example, when switching from stucco to EIFS, joints will need to be incorporated where there were none before and this can significantly impact the aesthetics of the building.
EIFS have a carbon footprint that is three times smaller than stucco according to the United States National Institute of Standards and Technology. Unlike stucco, certain components of EIFS are also much easier to repair, negating the need to replace the whole project and eliminating the subsequent waste.
EIFS is about ten times lighter than traditional stucco materials, and the fuel used in transportation is significantly lessened by up to six times. The lightness of EIFS also adds to it being the better cladding of choice for projects requiring a lighter building envelope. When making the choice to change from EIFS to stucco, it is imperative that the supporting wall as well as the substrate in question can handle the excess weight from the stucco application.
Laboratory testing has also proven that EIFS are more flexible and offer up to 84% more energy efficiency than similar wall cladding systems, whereas the energy efficiency of stucco is significantly low.
The expanded polystyrene foam (EPS) used in EIFS is not noncombustible, while stucco is noncombustible. It is important to note however, that incorporating EIFS onto a wall that is already up to necessary fire codes does not detract from the supporting wall’s preexisting fire resistance in any way.
EIFS can be anywhere from just under an inch to over four inches thick. If changing over to a material like stucco, which is only generally 3/4 of an inch thick, care must be taken with regards to openings and items like windows and doors for which the logistics can change. For example, the movements of doors or windows can be impacted if all of a sudden the thickness of the surrounding wall is altered. Where there were none needed, flashings may also now be necessary to allow for proper drainage in some areas.
The entire R-value of a wall, or measure of thermal resistance, may be compromised when changing over from EIFS to stucco because EIFS is insulating and stucco is not. Further insulation will be needed when changing from EIFS to stucco to meet building codes.
Hardness and stiffness
EIFS is an extremely flexible wall cladding that can bend as a building shifts, whereas stucco cannot. Additional care must be taken when switching over materials to ensure that stucco does not crack, such as increasing the stiffness, depth and thickness of the studs.
Because EIFS is more susceptible to external forces and impact than stucco as it is a softer material, thicker reinforcing mesh or other protective measures can be taken depending on the likelihood of such events that are not necessarily needed for stucco.
Ontario unfortunately receives its share of strong winds and tornadoes. Because of the way stucco is installed, it is able to withstand inclement weather due to its material and fasteners. EIFS does not function poorly in high-wind situations, but the tops of high rise buildings and the effect wind has on them should be carefully studied and reviewed before switching over to EIFS from stucco. The EIFS walls can be made more wind-resistant according to manufacturer specifications.
Depending on building codes, EIFS with drainage may have to be intalled when switching from stucco instead of barrier EIFS. They may be a bit more expensive, but it’s something to consider.
Obviously there are a couple of factors to contemplate when considering switching to EIFS from stucco, or the other way around. Thinking about each one carefully and weighing the total cost of each application can result in a successful overall changeover.