A critical piece of knowing how to restore a building’s exterior is being able to identify exactly what type of materials were used. While stucco and EIFS exteriors look extremely similar, they are dramatically different materials.
Traditional stucco is sometimes referred to as hard-coat stucco and is made of sand, lime, Portland cement, and water. Think of it like an extremely fine concrete applied to the exterior of a building. Stucco can be installed on a concrete base or on metal mesh applied to a frame finish in either two or three coats.
With traditional stucco, you get a hard finish that is extremely durable to impact, sheds water, and is breathable to allow water vapor to escape because it’s a porous material.
Exterior Insulation and Finish Systems (EIFS)
EIFS is a newer product sometimes referred to as synthetic stucco. The system includes an insulation board and several layers of acrylic to create a finish that looks similar to stucco. It’s often applied over an exterior sheathing product such as plywood, although it can also be applied over concrete.
While the acrylic coatings can repel water, EIFS systems can be subject to moisture penetration, which can then become trapped inside the wall. When that happens, materials beneath the synthetic stucco may begin to rot, which can cause a wide range of issues. However, some newer EIFS systems have been updated to include a moisture barrier that addresses this issue.
How can you tell the difference?
It’s difficult to tell whether a surface is traditional stucco or EIFS just by looking at it. One possible way is to knock on the exterior surface. If it feels like you’re knocking on a brick wall, it’s probably traditional stucco, whereas a hollow sound could indicate EIFS. Another way is to inspect any holes in the surface required for light fixtures, door bells, or gutters. If you remove a light fixture and can see foam board inside the hole, it’s EIFS.
If you still aren’t sure whether your exterior is traditional stucco or EIFS, contact a professional with experience in installation or restoration of these exteriors. They can help you identify the type of exterior and any maintenance work necessary to restore it.