What is the difference between EIFS and stucco?
Friday, October 25, 2019
EIFS is an acronym for Exterior Insulation and Finish System. It has been a popular exterior finish material in the Gainesville area for about the last 20 years, and is also called synthetic stucco: essentially a foamboard and fiberglass mesh attached to a wall that is covered with a polymer-based material, and then textured to look like historic stucco. EIFS has been in use in Europe since the 1950s, and in the U.S. since the late ‘60s. It is typically used on wood-framed houses.
Traditional stucco is different. It’s made from plaster with water, sand and lime, and has been used for centuries as finish surface over a masonry wall. While the composition of stucco has changed over time, it is still most often applied wet over a masonry surface, such as concrete block.
Why is water damage a concern?
Traditional building materials used on the exterior of residential homes will allow water or water vapor that finds its way inside to eventually escape back to the atmosphere. EIFS, however, is a “barrier” type material, and blocks the movement of water and water vapor – it does not “breathe.” While barrier-type materials have excellent insulation properties, they are not good at dissipating moisture. This, coupled with interior vapor barriers that are often required by building code, can lead to prolonged moisture intrusion and, eventually, rotting of materials.
Water can find its way inside through any cracks that have developed, or through any areas where the EIFS abuts a different material, such as door and window frames, or at the roof. If the EIFS continues below ground level, any cracks or openings in the finish will allow moisture, as well as wood-destroying organisms, such as termites, inside. When prolonged moisture intrusion of the wood behind the EIFS reaches 30%, rot and mold growth will begin.
Has water damage occurred or is it likely to occur?
Your home inspector’s preliminary visual review of the exterior wall surfaces may determine if water damage is actively occurring, as well as whether it is likely to occur due to improperly installed synthetic stucco. There have been many reported cases of EIFS manufacturer installation instructions not being followed correctly by builders, leading to problems. There are several different approved installation methods for EIFS, and we are familiar with them, along with using an infrared camera as part of the evaluation.
Key Points of a Visual inspection
- Ground Contact: EIFS should not continue down a wall into the ground. It should terminate no less than 6 inches from finished ground level.
- Drainage System - Called a “weep” or “weep screed,” a continuous drainage slot at the bottom of an EIFS wall has been required for about the past 15 years. Because it is inevitable that some moisture will get behind the surface, the drainage opening allows it to exit the wall, and also is easy for an inspector to identify.
- Roof Flashing: Kickout flashing should be installed where the EIFS meets the roofline. If this is missing, there is a good possibility that water is entering the wall cavity. We also check for any areas that feel soft or are discolored.
- Joints Around Windows and Doors: We check caulking joints around windows and doors to make sure that there are no cracks, even small ones. If wood on window or door frames feels soft, or it is discolored, water may have entered the wall assembly around the frame; and
- Areas of Cracking or Bulging: If there are cracks in the EIFS itself, moisture will be able to infiltrate the wall assembly and cause rotting. Bulges can indicate that coatings are delaminating or detaching from the polystyrene board.
If evidence of damage or moisture intrusion is found, options for repair should be explored. These may include anything from additional caulking and sealing to removal and replacement of synthetic stucco sections. So it’s best to catch any possibility of water damage to EIFS at the earliest stage possible, before any lingering moisture has had time to cause rotting.
Also, see our blog post What is the difference between Acrocrete and EIFS?
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