The Dangers of Installing Exterior Insulation Finishing Systems Below Grade in Canada
EIFS is commonly used in applications it was not necessarily intended or designed for. While some of these uses are innovative, others can be catastrophic. EIFS is a very well-suited finishing material that poses no problems when installed properly.
EIFS being installed below or near grade, the portion of a building that is below ground, is one of the largest reasons for EIFS-related structural damage and failure in commercial buildings and homes.
In 1999, the National Association of Home Builders Research Centre found that below grade installation was one of the main reasons for water entering EIFS. The study stated that newer homes were experiencing severe structural damage because of the leaks and accumulation of moisture from rain water. Even though the study was conducted in the United States, it applies to all climates, especially that of Ontario considering the amount of snow we receive.
Water entering EIFS
EIFS are not a waterproofing system, and EIFS isn’t easily waterproofed – although some small, vulnerable patches can be sealed at the surface to prevent dirt and water from penetrating it.
Water is the largest problem with using EIFS below or near grade. Water can get into the EIFS and eat away at the substrate, depending on its material. Water that sits on top of the soil and originates from rain or melting snow is drawn up into the EIFS due to a wicking effect, the same phenomena that allows water to flow through soil. Continuous contact with water can also keep the finished top coat of the EIFS soft, allowing even more moisture to penetrate the material. If the foam is below grade, any residual water vapour can condense and settle, and because it evaporates slowly, it can rot important structural components of the home.
Another reason that this water is so damaging is that once it’s trapped, it can’t escape easily. EIFS is not a breathable material, and therefore the water trapped deep within cannot evaporate. These issues are also very difficult to spot before the damage becomes significant and more serious.
Even if the foundation where the EIFS is intended for application already has waterproofing, it may be more difficult for the EIFS to adhere properly, and any external fasteners used to connect the two will only puncture the preexisting waterproofing.
The temperatures of southeastern Ontario can also have serious problems when it comes to winter soil. When the water in the ground expands as it freezes, it can damage or even pull the EIFS off of the wall if it’s below grade.
Another serious problem that arises when using foam insulation below or too close to the ground is that it creates easier access to a building for pests such as termites and ants. Termites can burrow in the EIFS foam and tunnel until they get to wood on the other side, where they wreak havoc on the structural integrity of wooden components. Many of these pest-related issues are difficult to see or discover until it is much too late, and are often easy to miss as the primary damage or evidence of pest activity is hidden deep within the foam while the exterior of the EIFS remains intact. The extending of the EIFS below grade can also make it difficult to implement successful pest-control measures.
So, why would anyone use EIFS below grade?
Many instances of EIFS being installed below grade are for appearance and aesthetics purposes. Instead of having the EIFS start a few inches above the ground as per recommendations and as required by some building codes, it is applied so it meets or extends below the ground for a sense of continuity on the exterior wall. Installing it this way might create a nice appearance, but the issues that arise can be extremely costly to repair and in the end it’s just not worth it.
What would allow for EIFS use below grade?
Desert soil with little moisture might allow for successful installation of EIFS below grade, but certainly not the soil varieties found in southeastern Ontario or much of Canada. Other mitigation techniques would also need to be implemented, such as additional waterproofing, proper drainage materials in surrounding areas and extra reinforcement such as wood or more foam around the EIFS. Otherwise, EIFS should be installed above grade and have a six to eight-inch gap between it and the soil.
Some EIFS problems can be easily repaired or reversed at little cost, however the issues that arise when EIFS is installed below grade can be quite severe and may actually result in it having to be removed and replaced completely, which can end up being very expensive. Installing EIFS above grade as well as properly sealing the bottom of the EIFS can help avoid these problems. One of the best ways to protect your investment in EIFS, like any other in a home or business, is to ensure it is installed properly.