water (downspouts, etc.) is carried away from the excavated area, if
this winds sitting in a pool of water your chances of completely
waterproofing it with a membrane(s)are about zero, I would always spec
Xypex as an admixture even with proper drainage (you have none), your
best chance on the walls is to have a waterproofing firm install a
liquid membrane of some kind, I've seen ParaSeal used under slab. The
best advice is to get a waterproofing consultant on board to spec,
observe,& sign off. Detailing is critical, especially at corners &
material transitions, but even a perfect design (and I've never seen
one) is useless unless someone who really knows his stuff inspects the
installation process and signs off on it. This not something you want to
wind up responsible for--the repair cost can be mind boggling.
The owner's needs & expectations are also critical. Is it OK as an
occasionally damp basement, or do they want hardwood floors in a
finished room? (it would be simple if it was supposed to be a swimming
pool, but a disaster if it becomes one by accident). Discuss it with the
client but don't take on the responsibility for a waterproof basement.
I always get the waterproofing off the structural drawings & onto the
architectural and specifically exclude waterproofing, drainage, and
ventilation in my contracts.
Chuck Utzman, PE
Tom Monti wrote:
> I am working on a project where they want to add a full basement to an
> existing single family home. This is on a flat lot where the water
> table according to the soils report will be approximately 8 feet below
> grade at its estimated highest point. The city will not allow under
> slab or behind the wall drainage or sump pumps. I don't have a problem
> designing them for hydrostatic pressure, but I am concerned about
> moisture intrusion into the basement. Their answer is to install good
> waterproofing. Any advice on a good waterproofing system or
> disclaimers that I should add to the drawings? The project is in the
> SF Bay Area. In my mind, all waterproofing systems eventually leak.
> Thank you for your input.
>
> *Thomas L. Monti, PE*
> Morgan Hill, CA
>
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