# French Drain through Load Bearing Wall?

We have a bi-level home on a hill; recently the garage, which is about 6' under ground, has been taking on water after a heavy storm. The house is on a slope, and we know that hydrostatic pressure is the culprit. We asked 4 contractors for ideas/bids and all suggested a French drain-sump pump set-up, which seems like the correct way to go. The sticking point is this; the garage is a 2 car, divided by a cinderblock, load bearing wall. One contractor says he can just go through that wall, and around the perimeter of the garage. This makes the job much less expensive, instead of going around 6 walls with the drain, he is going around 3, so the linear footage is much smaller. He says, the hole that would be cut through the load bearing wall is insignificant, and will be recemented anyway. I tend to agree with him after thinking about it, but I do not want to wake up with a collapsed/cracked wall one day! I would love to hear everyone's opnions.
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Gritz_1 wrote:

How is the garage situated in relation to the rest of the house? House in relation to slope? I don't understand the 6 walls. If uphill is at the back of the garage, then it would seem that a drain across that wall would keep the water out of the garage. I know I'm missing something :o)
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Yes, tough to explain without picticures! Where the water problem occurs is at the back of the house/garage. We sit on a hill. The entire property slopes down to the street. The garage is on a slab 8" below the slab that leads to house. No problem with water on that level. The garage has a slight slope that tilts toward the the back of the house, not towards the garage doors. You are not missing anything. Drain across the back wall is absolutetly correct. The load bearing wall I mentiond intersects the back wall. What the contractors all said, (in unison, I might add)is that the other walls need drains as well. If you were looking from above, left wall is an outside wall, so that would kind of make sense to me. The one contarctor, as I mentioed, just said, do the ouside wall, back wall, and 5' up the inside wall. Are you saying the back wall drain wouldbe sufficient? It's really not a a lot of water that we get, and it's sporadic at best. The "6" walls come from doing the left, back in garage 1, up the center (LB wall), down the LB wall, back in garage 2 and 5' of the inside wall! Thanks for the input.
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if your asking about a 2 or 3 inch drain line thru a concrete load bearing wall thats common and wouldnt effect the wall strength.
around here interior french drains between sides of load bearing walls are dug under the footer. its no trouble water finds its own level.
you should try for a gravity drain to daylight if at all possible, so power outages and pump failures never can cause a flood.........
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clipped

No......I don't know enough to tell you what is right or wrong. My thought is this: the problem is with heavy rain and is sporadic. That suggests to me that the slope is bad and you are getting runoff. not groundwater. If that is the case, then stopping or diverting the water so it runs away from the garage might cure the problem and, at worst, just require a french drain across back of garage to........? In conjunction with that, a little grading and/or addition of soil across the back to minimize what reaches the area in back of the garage..

Sounds like something that looks great on paper :o) Where is the water supposed to wind after it is collected?
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Norminn wrote:

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Being in the epoxy coating business, I might suggest sealing and waterproofing the wall with epoxy paints. Outside would be best the could also be done coating the inside of the wall.
very similar to coating sewer manholes - they get coated inside because you don't want groundwater/surface water entering the manhole and 'overflowing' the system.
paul oman
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Gritz_1 wrote:

My opinion is to regrade the back yard, and put in a swale to redirect the water around the garage. If that isn't enough, bite the bullet, and dig out the backfill on the outside of those 2 sides, and put in a proper foundation drain, with proper gravel and whatever above. While the trench is open, replace the waterproofing on the outside of the wall. Interior french drains are a second-best solution in a basement, where the floor gets almost no load. But putting them in a garage, thereby breaking the link to where the slab sits on the footer, seems to be asking for trouble. Not to mention, how warm does the garage stay? Ever get cold by where the big doors open?
IMHO, water should be redirected or stopped outside the basement wall.
(Yes, I just had a site survey from a 'reputable' basement waterproofing company, and even after I told him I grew up in the business and knew better, he still tried to sell me snake oil. As he was packing up, he even tried to offer me a discount if I would sign a contract and give him a check right then.)
But having said all that- no, a small hole in the bottom corner of the dividing wall, to tuck a tile under there, won't seriously affect the load-bearing capacity. I assume you have a door through the wall already? Just stay away from right under the door frame.
-- aem sends...
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From one who has gone through the drain problem from you know where, may I say that your suggestions are the first ones that make any sense.
Gritz has tried to describe his problem, but it is a bit difficult to do so. And I can understand that.
Your comment about french drain people selling snake oil is absolutely right. They wanted to do that on my property for \$1-2000. The last owner sold rather than deal with it. I decided to do it myself. I found my problem was caused by construction fill of a deep ditch between my house and the neighbors; the street slopes downward toward me and the lawns are even with the curb. As I said, apparently before the houses were finished there was a big ditch there until they filled it in. The problem was that they used construction sand: very porous.
After digging it all out, I could see that the groundwater would go six feet under the surface, then under my crawl space, which was like a swamp. The french drain guys wanted all that money to dig a 24" french drain. A lot of good that would do!
Like your suggestion, I dug out around the house. The crawl space had been filled in with concrete block some years ago, but it wasn't sealed very good. I sealed and waterproofed it, then put a border of 4mil vinyl sheeting on it before I filled it in.
Where the snake oil guys would have put a 24" french drain, I dug a 50'X2'X6' deep trench, put a 4" socked slotted pipe at the bottom, then a sheet of 4mil vinyl along the side of the trench. The pipe went around the house to the lower side, where I got permission from the city to put a drain in the curb. I tied my gutter drains and a basement drain into it.
This drastic fix works. We've had less than moderate rains so far this spring and haven't had any for nearly a week, but that drain that comes out of my curb is still running down the street today. It shows no sign of stopping.
They would have put in the french drain and missed all that water!
Oh, by the way, that crawl space is dry as a bone, even in rainy weather. The partial basement, which used to be slimy, is now dry as a bone.
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I am the other half of your success...................... failure.
heres what we tried.......
had foundation mostly dug out to footer level, found old drain line clogged completely, water proffed walls, installed new drain line, and many tons of gravel since we had to remove all the sidewalks and steps that suurrounded a good bit of the home. then regraded entire yard, installed new downspout drains going to street and daylight, replaced entire yard........
If it hadnt been DIY it would of likely cost 20 grand...........
guess what?:(
Well the water no longer bothered the walls but still came up thru floor with every heavy rain........
had interior french drain installed, that fixed it finally............
conclusions exterior work costs a fortune and may not be effective........
the costs for backhoe, gravel, dump truck to haul away excess dirt the gravel replaced, rebuilding lawn, tons of hard labor,new sidewalks and steps, well it all looked nice and gave the home curp appeal, we sold it some years later.
but the interior drain worked better and only cost 3 grand.
sometimes water table actually rises and all that exterior work is a grand waste of time and money/
smart builders install interior french drains in new homes, today its frequently a building code requirement
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snipped-for-privacy@aol.com says...

Yep.
Around here every basement is a hole in clay. Of course water finds it. The people living on *top* of the hill I live on eventually got an interior drain tile system.
Banty
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snipped-for-privacy@aol.com wrote:

(snip)
had to remove all the sidewalks and steps

Builders in your area still offer basements? They have mostly vanished around here. (I think it is stupid, but that seems to be the way 'standard practice' is heading.)
2 different problems- surface water saturating the topsoil and coming through wall, and high groundwater levels. A lot with high groundwater really shouldn't have a basement, but if a basement is considered a 'must have', and lot can't be resculpted accordingly, yes, interior drainage may be the only way to go. I remember a McMansion on north side of Indianapolis I worked on in early 70s- no other house in the sub had a basement. Thus guy <absolutely> insisted on one. The hole kept filling with water. We finally put in exterior and interior perimeter tiles, an X of tiles across middle of slab, a 5 foot deep 30 inch sump pit to collect it all, with an overflow tied to an exterior sump pit (really a precast manhole) in front yard, that could be used to pump from in an extended flood situation.
I still say water should be redirected or stopped outside the basement perimeter. If that can't be done without heroic measures, well, maybe that was a bad place to put a house/basement. (Not all lots support basements, and not all lots are buildable.) Making interior french drains code-required strikes me as giving designers, civil engineers, and builders, an easy out. It may be a solution for an existing house where you didn't know beforehand (My sister's house had them added before they bought it), but in new construction, it screams 'cheap shortcut'. Gotta do the homework before you build a house, including test holes and having an engineer do a site survey, at least for the first houses in the sub. And, of course, the lot has to be graded right. I see sub after sub with lots as flat as dinner plates, or yards that slope all the way to the foundation.
Maybe code should require leaving the hole open for at least one rainstorm plus 48 hours, to see what the seepage patterns are, before you do the foundations? :^)
Having said all that, I'm glad it worked out for you.
-- aem sends...
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aemeijers says...

It's never been explained here that I've seen - exactly **why** is an exterior perimeter drain preferable to an interior tile drain??

They do something like that - percolation tests. I heard from a neighbor my house was on a lot with a marginal test.
Banty
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I can think of 2 reasons offhand-[from personal experience]- lower humidity in the basement, and less chance of filling the block up with water & 'rotting' them.
Jim
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my home with bad water troubles, found out later a tiny vreek ran thru the area before the homes were built in 1950..........
fill in a creek the water still flows underground
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What exactly do you mean by 'rotting' the concrete block?
Interior french drain systems usually include a way to drain the bottom blocks of water, if any, to redirect along with water in the trench.
Banty
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Banty wrote:

If there is water in the block, that means the wall is always damp, even when it 'feels' dry. Concrete is not waterproof- that is what you see when that white haze (efflorescence?) shows up near leaks- the white stuff is minerals the water leached out of the concrete and mortar, thereby weakening it. Doing construction demo as a kid, you could always tell walls that had been wet long-term- you could pop the bricks or blocks apart with just a tap. It eats away at the mortar first, and then at the concrete itself.
And when you have water exposed to the heated air of the basement, even if hidden under the trim covering the slit trench along the wall, that can't help but spike the humidity down there. Even when I don't have visible leaks in summer, I have to empty the dehumidifier every 2nd day. (Sure wish the floor drains hadn't rusted/teakettled shut...:^( ) My sump pit has been bone-dry since I have lived here- it is surface water coming down through the backfill and failed waterproofing, migrating through the walls. I'm convinced replacing the outside drains (assuming they are there at all) and redoing the waterproofing would fix the problem, but since the basement doesn't actually flood, it would probably be a money loser at resale time. (Trust me to buy a house right when the 5-7 % a year appreciation in housing values stops dead in its tracks. Value of this place is MAYBE going up at the rate of inflation.)
Interior drains beat a wet basement, but a waterproof basement envelope is what you should strive for.
-- aem sends...
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-snip-

Usually is a mighty big word. And even if they are installed, a small weep hole is more likely to clog than a 4" perf-pipe.
Another advantage [in northern climates] of keeping that groundwater outside of your house is heat loss. The best insulation is on the outside of your block under a waterproof membrane. Then the slab and walls become part of your heat sink. Water running through is a constant source of 50degree or less coolant.
Jim
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if your building a brand new homew install BOTH, the trouble is most of us own existing homes, and beyond the obvious downspot clogged a interior french drain is the MOST effective.....
been there done all this.....
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?? "big word"
I've seen what B-Dry does. And what Vulcan did on one part of my house. B-Dry much better - decent sized weepholes in each cavity of the bottom block, very unlikely to clog. The weepholes *drain into* the trench with the perf-pipe (of whatever sort). Both are present.

We're talking about taking groundwater and redirecting it, from just outside the foundation at the footer, vs. just inside the foundation. How much of a heat sink difference do you think that is?
BTW, I agree that, at least around here in our clay-shale geology, new construction should have *both*. But most of us like myself purchase existing houses.
Banty
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Good thing you were apparently situated to do all that yourself so I won't ask you about labor, bringing equipment to the site, etc. (did you compare even the costs of materials, like the gravel, so what the "snake oil" would have been??)
Banty
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