Garage/basement seepage - interior fix?

[ptmoss]

Yet another wet basement....

My basic question here is this -- has anyone had success with sealant products inside a structure? In this case, a garage and basement.

Here is the problem:

A house has been built, about six years ago, into a steep hillside with a high water table. A garage is on the uphill side of the house and it has a four foot concrete wall above the level of the slab to act as a retaining wall. Water comes in for 2-3 weeks every spring through some cracks along and near the base of the wall at the uphill side.

The second spot where water comes in is through the uphill side of the basement, again near the toe of the wall. This corner of the basement also shows a small (+/-6" diam) spot of bedrock poking through (directly at the bottom corner). So apparently the slab and wall were poured directly on bedrock in at least that one location. Again, water seeps in through a few cracks for 2-3 weeks each spring.

We talked about the possibility of excavating around and being pretty agressive with some drains around - although the house had basic footing drains (he thinks) installed when the house was built. Expensive, yes, and actually quite difficult at this site, especially after seeing the bedrock.

What the owner would like to try, and I thought it was worth a try, was a product he found doing a web search. It's called "Sani-Tred LRB" and is a polyurethane product that gets applied over the wall and floor. Its supposed to have serious adhesive qualities and penetrate into cracks and the like.

I'd love to here if any of you might have had experience with this or similar products.

Thanks, Pete

 

[Focht3]

Do waterproofing products work? Some say 'yes', others say 'no'. (I tend to vote 'no' for all but a few select problems.) Your client has already been dealing with this for six years. If he tries the waterproofing paint and the walls still leak next spring, then the "cheap" answer didn't work and he will have to install drains to fix the problem. But are you really asking the appropriate question?

I'd be much more concerned about whether the walls were designed to resist the water pressure. If not, then your client may have a very serious problem on his hands. What did the builder say when asked about the problem? The original designer? Any written correspondence?

This is the kind of problem that gets worse, not better, with time - and paint.

I hate to say this, but your client should probably consult a lawyer familiar with construction law before any more time passes. I'd mention that option in written form to protect yourself - so he doesn't sue you later...

 

[dicksewerrat]

Some chemical grouts are very good at stopping water infiltration. They are applied under pressure to ports installed in the structure. They will move out into the soils and seal the water. See if there is a local contractor that seals sewer manholes, pump stations or large sewer mains. They may have what you need. Unfortunately these products are not for the weekend contractor.

 

[ptmoss]

Thanks, I'm not actually worried about liability on this one. I'm not sure if he ever contacted the original contractor.

I was hoping maybe someone had heard of a similar product. I'm asking around to see if there is a contractor who does the chemical grouting, that might be another solution.

He has also talked to a contractor who I think was planning to add drains inside (via breaking through the slab) leading into a sump. I didn't think that would work too well due to the ledge.

Sure isn't an easy after-the-fact fix!

Pete

 

[erich]

While I was in school I worked at a Building Supply store, the contractors swore by a product called Thoroseal. It is a cement based coating made to seal concrete and is supposed to be vapor permeable. I don't know if it works to fill cracks but I seem to remember that there was a host of related products by the same company.
Erich

 

[KRSServices]

While not exactly the same situation, we (my parents) had a residential area built on slope, albeit gentle, and prone to groundwater seepage in certain areas (typically basements) in the homes. Some people chose sealants, etc., others chose the aggressive route of excavation to the footings and installation of a non permeable membrane and drain pipe (option we chose). While all the solutions stopped the leakage initially, the "inside" sealant options over time either found another route (seepage into the house) or resumed in the same spot depending on the product used. My parents seepage stopped and never returned. This was about 20 years ago. About 5 years ago my parents moved away and to that time, the seepage had not returned, while other homes had numerous owners and tenants. Some chose the same option as my parents, others continue to "plug it up". I cannot provide any advice other than take my experience for what it is worth. Good Luck!

KRS Services

http://www.krs-services.com

 

[ptmoss]

Thanks everyone, I appreciate the replies.

 

[BigH]

My dad had some water seepage problems too. He didn't use any sealant. There was a product on the market - made of pvc and shaped like a baseboard. You glued this on at the base of your wall - and it catches and directs the water around to a sump or other positive drainage - sort of like an internal wall drain. Water continues to "come in" but you catch it and direct it away from your floor. When I go back to IN for summer leave, I will look up name, if I can find it in my dad's old "stuff" and let you know the name.

 

[GeoPaveTraffic]

I have to agree with Focht3. Be very careful of exceeding the structural capacity of the walls. If you truly manage to seal the water out, in my experience a very difficult task, you could over stress the walls resulting in bulking and movement.

 

[cvg]

I'm not convinced that sealing the seepage would over stress the walls. You would be assuming that the small amount of seepage (my assumption) is acting to relieve the pressure, similar to weep holes. Not likely, unless you have a large amount of water coming through. Sealing out the nuisance water will not - in my opinion - cause an undue increase in pressure on the outside of the wall. That said, you probably do have water pressure on the wall, and as stated by Focht - I hope the walls can take it... I like the idea of breaking through the wall and adding a drain. You could use a core drill to drill weep holes and then provide some sort of a trench drain in the floor to remove the water. This probably would help to lower the hydrostatic pressure on the wall.

 

[dicksewerrat]

You shouldn't have a problem with increasing the pressure on the wall because you said that it is a steep hillside. The water table will just flow around the house as if it were a large boulder.

 

[ptmoss]

Yes, that;s right, it's a steep hillside. It's also a relatively small volume of water seeping in - unless of course you're the one cleaning it up! (I believe it was about a shop-vac full every day for the two weeks or so the seepage lasts).

 

[Focht3]

Okay, they water volume - so far - has been low, and a build-up of pressure doesn't seem likly under the present circumstances. But homes have a design life of 50 years or more; what about the extreme weather pattern? Future changes to the site - or off-site - that could affect drainage?

We can draw nice, pretty flow lines around the structure representing the theoretical flow paths and water levels upslope of the foundation. But these drawings are little more than crude estimates - even fairy tales - on rocky hillsides. I believe that a prudent engineer - and homeowner - would attempt to relieve the water pressure rather than playing ostrich and covering it up with a fancy paint.

Ultimately, it's the homeowners' call, though. After all, it's their investment...

 

[stadry]

IF the water seepage's as small as you say, i'd favor the polyurethane method,,, get someone who does epoxy injection - prime resin makes a great product - you also don't mention block of pcc - that makes a difference, too,,, soil acids & water'll eventually reduce block to crumbs,,, haven't seen enough to determine concrete block as of yet - before anyone raises their hands out there ?,,, mortar's the same on both blocks,,, & i haven't seen any indication that there's a mason yet who uses latex in his mortar for water resistance,,, the guy who said do it right the 1st time's got the right idea, tho - sounds like he's already paid for his boat best

 

[bartshippee]

Has anyone done a quick estimate of the additional water pressure against the wall? Wouldn't it be simply a triangular stress distribution of the unit weight times the height of soil against the wall (assuming fully saturated ground conditions)? With a 4 foot high wall and assuming 6" above grade, it would be 0.5*gamma_water*(4.0-0.5)^2. This is an added pressure of about 385 lbs of additional force per foot. This doesn't sound like an awful lot of additional pressure for a wall to handle for a 10" basement wall. I know I am making some leaps of faith and assumptions here, but is this how YOU would figure it?

 

[Focht3]

Yep.

Problem is, we don't know how the wall is reinforced, or where the lateral load is transferred. And the wall isn't continuous - or very thick - in spots. ptmoss said in his original posting,

... This corner of the basement also shows a small (+/-6" diam) spot of bedrock poking through (directly at the bottom corner). ...

If the builder didn't bother to remove this rock protrusion, how can we feel good that the wall has a reasonable thickness, or is adequately reinforced? (We don't have any information on the wall design or construction other than its height.)

Sometimes it's the small details that are the best clues!

 

[ptmoss]

Thank-you all for your posts. You might be interested to know that the owner went and had a contractor dig 6" along the perimeter of the walls (inside) and down to the footings. Filled it with stone and has some type of pipe/trough built in to divert water to a sump pump and then outside.

Since I haven't seen it yet, I'll have to assume that they also went around that piece of ledge I mentioned.

Wouldn't have been my chosen alternative, but time will tell. If I remember, I'll find out next spring how it works out and re-post here.

Pete