Basement Waterproofing and Moisture Q&A
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Hello! My question is concerning a house I am looking at purchasing.
The problem is the basement did leak 3 years ago but apparently seems to be good
for now. The basement wall where the water was entering was repaired from the
inside of the house. Do you feel that this is a temporary fix or a permanent
one? Is repairing the basement wall from the inside as effective as repairing
from the outside?
There is a cement slab on the outside of the house right where the water
was entering. Would I be able to break the concrete up with a jackhammer if need
be or not? I can't tell if the wall is permanently fixed since the vendor did
not re-insulate the exterior wall and put drywall back up. There is no smell of
dampness or moisture in the basement. Thanks.
It is impossible to say if the repair is permanent, since we can't duplicate
the conditions that caused the original leak. Under the right conditions, any
basement will leak, so there is no definitive answer to your first question. The
fact that you can't look at the repair is not ideal, but is common in finished
basements where the owners want to get on with their enjoyment of the room. You
could hardly expect them to leave the repaired wall open forever, or to cut open
the wall for you unless you have committed to buy the house first.
Exterior waterproofing or the installation of a drainage system at the base
of the foundation walls is the most thorough repair for a recurring water
problem, but it may be an overly extreme solution if the original leak was caused by a
special circumstance, such as a broken or overflowing gutter or unusually heavy rainfall.
Perhaps you should try to find out from the seller how, when, and why the leak
occurred. The hole or crack in the wall may have been there for years, only
causing a problem under the "unusual" circumstance!
The cement slab you mention could be a part of the problem if it is not
sloped away from the foundation. If there is a slope away, even a slight slope,
the slab should keep the foundation dryer by directing water away from it. An
acceptable slope for a new slab near an existing structure is approximately one
inch of slope for every ten feet of slab. A slab can be raised to increase the
slope, it can be coated with new cement to the same effect, or broken apart and
redone. It really depends on how large the slab is and how much work you want to
get involved it!
I have done countless small crack repairs with various cement patching
products. If done properly, these repairs can last as long as the wall itself...
long enough to be considered permanent. If you decide that you want to open the
wall to inspect the patch, you might want to add a waterproofing coating (not a
sealer) over the repaired area before closing the wall. Think of it as a cloth
diaper over a Pamper... backups are always a joy!
Oh, and be sure to choose a waterproofing product designed to be used below
The grading around my house is not adequate. In fact, it slopes towards the
house on one side where a concrete walkway was improperly poured. I am planning
on tearing up said walkway, but need to know the best way to regrade the sides
of the house. I am getting conflicting info from landscapers and from sources on
the internet. I believe that this will alleviate the problem of moisture showing
up in my basement which seems to be most pronounced on the worst graded side of
CT from Washington, DC
Your common senses are correct... eliminate the obvious first. Be
sure that your gutters (if any) are collecting the roof water and
directing it away from the house. The poorly graded walk is an obvious
suspect, and should be repaired.
If the source of the problem water is beneath the ground, neither
of these solutions will fully solve the problem. Movement of ground
water can be opposite the apparent grade in some circumstances. "The Original Basement Waterproofing
Handbook", is perhaps the single best-ever book on basement
waterproofing. If your "above" ground solutions do not yield
you the results you desire, this book is a must read! After all, knowledge is power.
We have a 55 year old house, with a 3/4 in-the-ground basement. I would like
to put up finished walls. However, the basement has a moisture problem with
efflorescence. I have treated the efflorescence with muriatic acid, with Zypex
and with bleach at different times through the last few years but the
efflorescence keeps coming back. The basement has good ventilation and we intend
on putting radiant heat in the floor. The basement is used year-round and is
kept very warm in the winter. If I treat the efflorescence once again and dry
out the walls, can I put up the vapor barrier, then 2x4 walls with insulation?
As I know you know now, from experience, efflorescence is a mineral
deposit caused by the migration of mineral-rich water through your
basement walls. In new concrete work, efflorescence can be a
short-term problem that may disappear over time as the new walls dry
out. However, if this is a long-term problem there are two possible
ways to eliminate it.
Removing all traces of the efflorescence by scrubbing and cleaning
with muriatic acid (most dangerous) or phosphoric acid (less
dangerous), drying the walls (they do not have to be totally moisture
free... just not wet) and applying a quality below-grade cement-based
waterproofing paint will definitely diminish and may even eliminate
the problem. Be warned... if other sealers or paint products have been
applied to the walls, there is the possibility that the waterproofing
paint will not adhere and the results may be disappointing.
You need to keep in mind that these waterproofing products are not
designed to stop flowing water. Actual leaks must be stopped either by
sealing them inside with a concrete patching compound (with a high
risk of eventual failure) or doing some more labor-intensive work
outside your home. The solution could be as easy as cleaning your
gutters. Then again, it could require diverting the water through
regrading (if the source is surface water) or even installing a drain
system at the base of your foundation. A professional evaluation might
be advisable so you can assess all your options. Perhaps the best book
on this topic is "The Original
Basement Waterproofing Handbook" by Jack Masters. You will know
as much about your foundation and ground water movement as many of the
waterproofing contractors you will speak to!
Once you have eliminated most of the moisture moving through the
walls, then and only then can you install your vapor barrier and
walls. Yes... even after the waterproofing steps you must still
install a vapor barrier because there will still be some low level of
moisture movement through the walls. You don't have to worry about
mildew… the vapor barrier will form a "stabilizing zone"
that will not promote mildew growth… there is nothing for the mildew
to feed on!
On the subject of basement walls, there are a few basement wall
systems that are both time and labor saving alternatives to standard
2x4 framing. One is offered by Owens Corning and features wall panels
with insulation and channels to run electrical, telephone and cable TV
wiring. Check it out at
Dow Chemical offers a somewhat different system, using specially
slotted 2'x8' Styrofoam panels that can accommodate a 1"x3"
nailer... suitable for the installation of wallboard. Using
"green" water-resistant wallboard... at least for the bottom
half of the walls... would be advisable. The one drawback to this
system is that all your electrical wiring must be on the surface...
visit your local home store for the scoop on surface wiring systems.
Ain't competition grand!
Don't throw away your dehumidifier. Any below grade area that is
anything less than swimming-pool-sealed will have some moisture
leaks... especially in the warmer months... and a dehumidifier will
keep the air moisture level acceptably low. Again, and I can't
reiterate this enough, you are doing this to protect your property and
your investment in what will be a wonderful renovation!
If you don't take these extra steps you will regret it. I have seen
too many basement renovations that did not take into account the
damaging effects of moisture and I have taken roomfuls of once-nice
furniture to the dump because of permanent mildew damage. You have to
be proactive so that you not only keep the value of your home but
increase it through wise use of your hard-earned money!
I have a ground water leak at my water service pipes during periods of heavy
rain. I have a poured concrete wall foundation. This pipe enters approximately
6' below grade. It appears that when enough water-pressure is achieved in the
ground water, it forcefully shoots along the pipe and into the basement.
I have it blocked to stop the spray and allow it to run down the wall to the
floor joint, where it enters the sump drainage system. However, I would like to
finish the basement so I am looking for a way to stop the leak. This is not a
large hole, so expanding foams probably will not work. Would applying a marine
epoxy with a syringe into the pipe/wall joint when dry form a permanent stop for
this leak? Do you have a different recommendation? I have seen you recommend
goop for other types of leaks, but I don't know if it would withstand the
NO from West Chicago, IL
Any breach through a below-grade wall has the potential for leakage. This
includes water pipes, electrical wiring and holes from the metal ties that held
the concrete forms together during the pouring of the foundation.
There are a number of products that are designed to stop leaks in concrete
walls, the best from a do-it-yourself perspective being hydraulic cement...
a.k.a. "Water Plug". This Portland cement product sets quickly and
expands while drying. It sticks tenaciously to new or old concrete and will
provide an excellent water seal between metal pipe and concrete... provided the
metal is not too dirty!
Hydraulic cement needs at least an inch or two of "depth" and a
half inch of width in order for the cement to have sufficient and reliable
holding strength. Carefully chisel or drill out (with a masonry bit, of course)
an adequate width and depth of concrete surrounding the pipe. Rinse off any dust
or dirt and, while the wall is damp, apply the hydraulic cement with a metal or
wooden tool, packing it tightly around the pipe. You can smooth the patch with a
damp tool but work fast, since you will only have a minute or two before the
initial hardening occurs. Once the patch hardens, your leak should be
permanently stopped. The ground water will still be there, of course, but it
will find its way to your drainage system instead of your basement floor!
I would not use marine epoxy in this specific instance. Expanding foam may or
may not work in this instance, again due to the depth of the cavity to be
filled. Not that there isn't a place for expanding polyurethane foam in sealing
leaks in concrete walls. For example, it is one of the few sure and easy
solutions for leakage through a pipe containing electrical wiring, such as from
a well pump or underground wiring for light posts. The foam will not damage the
wiring and will expand to fill every nook and cranny in the pipe!
And forget Goop! Though dry Goop is waterproof, it is not designed to stop
leaks, especially under pressure.
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