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- To: seaint(--nospam--at)seaint.org
- Subject: Foundation Waterproofing
- From: richard lewis <rlewistx(--nospam--at)juno.com>
- Date: Thu, 23 Oct 2003 16:02:00 -0500
I am working on an existing
office building with a basement. I have posted some questions about
this project recently and now a new issue has come up. The basement
extends out beyond the face of the building to the street curb
line. A pedestrian sidewalk is the roof of the basement in this
area. The sidewalk slab sits on 1/2 the wall
thickness. The street curb sits on the outer half of the wall
thickness. It looks like before they poured the curb they put down
about 1/2" thick asphalt to waterproof the joint between the curb and the
The City is reconstructing the street and wants to remove the
curb. The owner is concerned about water leaks into the basement due
to disturbing the curb. The City has come back and said they will
consider putting a waterproof membrane down before installing the curb.
have a couple of questions I would like help with. First, I think the
right material is a prefab membrane that is laid down on the wall, verses some
kind of canned mixture that hardens in place. Would this be a correct
assumption? Any words of caution of preparation of existing concrete
for the membrane application?
Second, I have a question about what
material might be best. You see the joint is a 'Z'
shape. The foundation wall is vertical till you reach the
top. Then you go horizontal the width of the curb, then you go
vertical again to the top of the slab. It is like a brick shelf, only
for the curb. I know bends will be weak points. Any
suggestions for the best way to do this? Water that is blown onto the
sidewalk will run over the curb/slab joint to the street. I see this joint
as being caulked with a high quality sealant.
Third, usually there is a
protection board on top of a membrane. I am wondering what is best to
do here. There will be differential movement between the curb and the
walk slab/foundation wall. Should there be some kind of protection
board that wraps horizontally under the curb and then vertically between the
curb and the slab? This would be about 6" horizontal and about 12"
Fourth, what kind of warranty should the building owner ask
for? Is 10 years practical?
My gut feeling is to leave the
curb alone since there presently is little leakage. The City is
pushing to replace the curb so it matches the rest of the project. Since
they are pushing it and hopefully will pay for it we want to specify something
that will work well into the future.
I appreciate any helpful suggests I