Buying a New Home? Better Check the Basement
Housing is making a comeback. Two major indicators of housing industry health – average home prices and home sales — are showing double-digit gains compared to last year. Even new construction has picked up. But as home buyers begin to feel confident that a home purchased today will gain value tomorrow, it’s worth reinforcing the importance of certain construction details.
Imagine what happens when bad weather arrives
An interior drainage system alleviates water pressure instead of allowing it to build up.
A beautiful entry door. Distinctive granite countertops. High-end appliances. Stunning hardwood floors. This kind of eye candy never fails to sway home buyers. But it shouldn’t cause a home buyer to overlook other details who’s importance has more to do with function than appearance. It’s smart to look beyond visually stunning “curb appeal” items when buying a home. Think about basement waterproofing, for example, it’s not important until you need it during rainy weather. Then it’s more important than anything else.
Basement walls are typically treated with a damp-proof coating –an exterior treatment required by most building codes. The coating should be visible above the soil back-filled against the foundation. Unlike a waterproof coating, damp proofing is only supposed to limit the amount of ground water that is absorbed by the masonry; it’s not a complete, fail-safe waterproofing treatment.
The hydrostatic pressure that builds up during extremely wet weather is most likely to drive water into the basement along the joint between basement walls and the basement floor. That’s where an active waterproofing system comes into play: French drains installed along this leak-prone floor-wall joint and a sump pump system that automatically pumps collected water to the exterior.
Waterproof paint and membrane systems usually fail because they allow water pressure to keep building up against basement walls, so that even the slightest gap results in significant leakage. In contrast, an interior French drain and sump pump system works with water pressure instead of against it. This system is designed to capture ground water before it reaches the basement floor and then pump it outside the house. An interior French drain system can be installed during new construction using a specially designed drainage channel. It’s also possible to retrofit this drainage system if a house doesn’t have one. Unlike exterior French drains which can clog with silt and plant roots, these interior drains are located in the “clear water zone,” away from soil and plant roots.
The nice thing about a well-designed interior French drain system is that it’s nearly invisible. A great example of this in action is from the CactusBoard system and with its retrofit version (WaterGuard® drain lines), a slight gap is created between the basement wall and the floor so that any water seeping in through the wall will find its way to the interior drain line and then to the sump pump.
Tim Snyder is a journalist specializing in sustainability, energy efficiency and home building topics.