If this is the preferred method, extreme care must be taken to ensure the waterproofing is compatible with the foam (e.g. Many waterproofing contractors use a spray-applied waterproofing product to seal the foundation walls, then apply the foam board to the wall immediately, using the still-tacky product to hold the boards in place until the wall is back-filled. XPS has a higher rated R-value per inch, although some studies indicate that EPS holds its R-value better over time.Īir/vapor barriers can be applied under the insulation, or applied on the exterior face as seen here.īoth materials will dissolve on contact with solvents. Usually, builders use two-inch-thick EPS or XPS rigid sheet foam. In most areas of the U.S., building codes call for an R-10 continuous insulation on the exterior of basement foundation walls. With the proper understanding of how water, air and moisture barriers work, along with continuous insulation, the waterproofer and specifier can rest assured the wall assembly will function as intended.īelow-grade continuous insulation is now standard practice. This moisture can allow mold and mildew, which will affect indoor air quality, occupant health, and the safety of the building. However, with today’s tighter buildings, water, air, and water vapor can build up inside the wall cavity. Wet construction materials would dry out. Water vapor would move through the wall assembly without creating any problems. In the past, homes and commercial buildings were drafty enough that the movement of moisture-laden air wasn’t a cause of concern. ASHRAE 90.1 defines continuous insulation as “insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings.” It can be installed on the interior or exterior of the wall.Īt a practical level, this is almost always rigid sheet foam, and this creates potential difficulties because it isn’t vapor permeable. One major update in the most recent versions of the code is the transition from cavity insulation to continuous insulation (CI). The 2012 International Building Code (for the U.S.) and 2010 National Building Code of Canada (which went into effect in 2012) continue to raise the bar. In many cases, this extra insulation is affecting how waterproofing is applied.Įnergy codes were first developed in the 1960s, and since then, they have moved in a single direction: higher efficiency and more insulation. Additionally, enthusiasm behind the “green building” movement has encouraged buildings that far exceed code requirements. and Canada are trending towards better insulation, and more of it. It’s clear that building codes in both the U.S.
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