Basement Waterproofing Methods in New Home Construction
Most of the time, this blog is about basement waterproofing “after the fact” -- water problems and waterproofing solutions in existing homes. The other night while watching TV I was reminded that the smart homebuilder (or the even smarter homebuyer) can ensure freedom from basement seepage problems by thinking ahead and putting water safeguards in place while the home is being built.
I was also reminded, while watching a show called “Modern Marvels” on the History Channel, that waterproofing a home involves areas other than the basement and this short segment does a great job of pointing out the trouble spots and how they can be avoided by proper design and construction practices. I wish, though, that it had included some of the other steps the homebuilder could have taken to make sure the basement of this beautiful new home would always be dry and comfortable.
This builder was absolutely right in making sure that the house has a solid, properly installed roof and in using house wrap as a vapor barrier to ensure that above-ground construction will be free from wind and water infiltration. However, the most important thing he said was later when he mentioned that any water coming off the roof or running down the vapor barrier was headed straight for the foundation…and maybe into the basement.
I must give credit to the builder in this TV segment because he did a couple of things right…sort of.
Foundation Waterproofing
The video shows a worker spraying a “rubberized membrane” on the foundation walls, which are constructed of cement block. If this is indeed a waterproofing membrane, this builder gets extra points. If however, it is merely a “damp-proofing” compound, he’s missing an opportunity to add real value to the home.
Insulation Board
After the membrane, another worker installs foam insulation board over it. This is great to protect the membrane and add R-value but it won’t promote drainage as well as a dimpled or channeled drainage board applied in the same fashion. Also, it would have been better to use pre-installed fasteners than to punch new ones through the membrane.
Then the builder got a big “attaboy” from me when he took the next step:
Exterior Drain Tile
Calling it a “French drain,” the contractor explained that installing perforated pipe in a bed of gravel around the outside perimeter of the foundation would carry water off to a sump pump. I couldn’t agree more but I think he made one mistake; he didn’t wrap the PVC pipe in a “sock” made of filtration fabric. This would keep out soil and “fines” from the gravel and help prevent clogging of the drain tile.
By installing only exterior drain tile, this builder stopped short of an ideal solution. Since he knows the value of drain tile outside a foundation, I wonder why he didn’t install it on the inside as well.
Interior Drain Tile
This is the workhorse of basement waterproofing and, when installed along with exterior drain tile, is the best protection from basement seepage you can have. In new construction, installing interior drain tile is easy and inexpensive, especially when, as in this home, a sump pump is already being installed.
Both systems will drain water away from the foundation, preventing cove seepage. The exterior drain tile will also drain the soil around the foundation, preventing shifting and saturation that may damage the concrete block walls. The interior drain tile will relieve hydrostatic pressure from ground water under the house that may eventually lead to leaks through even small cracks in the basement floor.
If I were giving grades, I’d give this builder a B. He obviously understands the importance of waterproofing and makes a pretty good effort to accomplish it in his new homes. If he’d only taken an extra step or two, he’d be at the head of the class. The housing market is still tight and prices are down but as I know very well, offering a high quality product is one sure way to please your customers and grow your business.
We don’t build new homes at U.S. Waterproofing but have helped to make more than 300,000 homes healthier since our founding in 1957 by making sure their basements are dry and their foundations intact. Please ask for our free advice on your home’s water problems…or let us know if there are any TV shows you’d like us to review.
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