Why we have two types of EIFS barrier and drainage

In the mid-1990s, Exterior Insulation Finishing Systems were frequently in the news because of significant moisture-related issues that were affecting homes in the United States. While these issues were primarily concentrated in North Carolina, EIFS other areas and climates are not unsusceptible to this issue. Because of water intrusion, the wood-based materials found in the supporting walls would begin to rot and give way to serious mould infestations. Similar issues are now being found with a series of condominium projects in Alberta, which are also being heavily reported on.

Researchers in Wilmington, North Carolina, conducted a series of rigorous tests and soon got to work trying to figure out why these problems were occurring. As a result of this endeavour, the main reasons were found to be improper installation and maintenance of the EIFS, not the product itself. Another reason that is important to consider is that the researchers found the system to actually be quite waterproof, but therein lies a problem as well – if water gets in, it becomes trapped and cannot get out.

Obviously EIFS were receiving an undeserved reputation, and EIFS more than anything is a shining example of manufacturers taking new problems into consideration while developing improvements to their product. And thus we saw the birth of the drainage EIFS, which are mostly meant for wood-frame buildings but that can also be used elsewhere.

The law

In Ontario, as with building codes, the laws differ from one municipality to another regarding barrier and drainage EIFS. For example, the City of Toronto may use the barrier EIFS, while other areas like Richmond Hill, Oakville and Burlington must incorporate drainage EIFS into their constructions and have had to for several years. In some areas, a combination of the two can be used in different situations.

Drainage vs. barrier in various situations

When both types of systems are close enough to the ground, they can be a haven for termites, ants and other bugs. This is especially true with drainage EIFS, as it already comes with convenient little holes for the bugs to crawl up through. Embedded trim at the base could be one way to solve this problem, as long as it contains holes large enough for water to drain out but too small to allow bugs to pass through.

Typically with barrier EIFS, the reinforcing fiberglass mesh prevents fire from reaching the combustible expanded polystyrene (EPS) core of the material. However, with larger drainage cavities, fire and the air that feeds it can move much more freely up through one EIFS piece to another.

EIFS is also an insulating material, meant to keep homes warm or cool depending on the season. They’re easily considered an energy-efficient “green” building material. However, when using drainage EIFS with larger drainage cavities, these insulating properties can be completely lost if the cavities are too large, and this must be taken into consideration.

Flashing must often be incorporated into drainage EIFS to properly route the water without inadvertently sealing the drainage holes during installation through the use of caulking joints. Flashings can be unattractive depending on where they’re situated with regards to the rest of the wall. If you have two storeys, for example, and the moisture barrier of both floors are connected as one, this would eliminate the need for flashings but not necessarily work for a multitude of storeys.

Moving forward

The application of stucco requires extensive trade knowledge and skill to ensure that cracks are subtle, whereas EIFS is similar, but simpler to apply as it doesn’t crack like stucco. In the 1980s and 1990s this led to many people employing unskilled laborers or people who wouldn’t bother to read the manufacturer’s instructions and therefore installed the EIFS incorrectly, resulting in these problems that are still having an effect on homes and buildings today.

The EIFS industry has taken all of this into consideration and improved tis product, providing the option of the drainage EIFS over barrier, but both can and are still used today. However, it must be noted that while drainage EIFS can rid itself of trapped moisture, it cannot rectify the consequences of poor installation and maintenance. Incorporating drainage EIFS cannot solve these problems alone.