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Basement Waterproofing a Basement that has Structural Clay Walls Using Weep Holes


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So I'm on the verge of pursuing a basement drainage system which uses weep holes. It's basically your typical French drainage along each wall where it drops into a trench some perforated pipe at the footer's edge and on top of that is pea gravel followed by a drip board that encapsulates both the trench as well as about 4-6 inches worth of wall after weep holes have been drilled into the block. The bad thing about my basement is that it has a few walls that were built with what I understand as being "structural clay block," which have horizontal voids. I believe these have been "kiln fired" (see attached image and judge for yourself). The house is an older home, likely built back in the 20s or 30s and this unfinished basement was dug-out after the home was built, which is one reason these blocks might've been used.

The contractor who will be doing the work seems confident that drilling into this kind of block is a simple issue and he didn't seem to expect any problems in doing it. I have 2 other walls that were recently built back in November with your common CMU block and I'm not worried about him drilling the holes into those, it's just these older clay blocks I'm worried about. My fear is that he (or his team) could either use the wrong bits or improper technique, whatever, and cause a confluence of failures forcing me to replace an entire wall.

 

Is it worth the risk? My heart of hearts says "no," but I'm so tired of worrying about rainwater in my basement that I'm close to taking the gamble anyway. Thing is, my yard lacks necessary height to properly grade it, so there's no options with any landscaping beyond what I've already tried to do (add berm against house, etc.). I've already extended my downspouts 20+ feet out from the house with solid PVC pipe, which did help a little. The new CMU walls that were installed this past November are the only walls that have a real perimeter drain. This drain line is connected to one of my sump pumps (I have 2). The drain line itself sits on top of the footer (the contractors didn't put it at the edge, but the top of the drain pipe is below the bottom block of the new walls by at least a couple inches and it's a 4-inch corrugated-perforated black drain pipe that was used). The perimeter drain does work, both pumps pump like crazy during heavy rains, but I just get seepage along the cold / cove joints and corners where the new walls meet up with the old. Through discussions, I've been told that it can be dealt with using this interior drain system / weep hole approach, but drilling into those clay blocks keeps me up at night. Would love to know if you think it's doable...

 

Thanks in advance.

clay_block_in_basement.jpg

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That's structural terra cotta.  historicbldgs.com/terra_cotta.html  If it is vitrified (and not just shiny from being wet) and the long edges are rounded, it could be telephone tile.  historicbldgs.com/telephone_tile.html

If it's not vitrified, then the shell is quite brittle.  Ask your contractor to show you how well he drills the sides of flower pots.  I've seen plenty of attempts at drilling - for termite treatments and installing anchors - that have blown out very large sections.

I don't much care for adding interior drain systems.  I never thought letting even more water into a basement and constantly pumping it back out is a good idea.  At best, it's the absolute last resort after exhausting every other possible solution.  The system, and even the installation, has caused serious problems in some buildings.  I've had plenty of expert witness jobs that are from waterproofing contractors irreversibly damaging old building foundations, including catastrophic failures.  These systems are intended for modern foundations with pretty standard footings.

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Bill, the problem with my home is that I don't have the yard to do any grading with and since my downspouts are already at 20' out, I'm basically out of other options besides spending gobs of cash on replacing each remaining older wall.  I wouldn't do that even if I had the cash to because the older walls aren't structurally problematic. But even if I did, I'd still be dealing with managing the water once it's inside because no way exists to prevent it from coming in, especially now that I have a perimeter drain line that channels water into a sump basin through the footing for it to be pumped out.

I guess the sad fact is that this house is landlocked because nobody has any real solutions for this situation except the constant critiquing of ideas that have been proposed, which isn't anyone's fault, it's just the cards in the dealt hand. The only options here--to my knowledge--is an interior drain system.

 

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56 minutes ago, Wolf_22 said:

Bill, the problem with my home is that I don't have the yard to do any grading with and since my downspouts are already at 20' out, I'm basically out of other options besides spending gobs of cash on replacing each remaining older wall.  I wouldn't do that even if I had the cash to because the older walls aren't structurally problematic. But even if I did, I'd still be dealing with managing the water once it's inside because no way exists to prevent it from coming in, especially now that I have a perimeter drain line that channels water into a sump basin through the footing for it to be pumped out.

I guess the sad fact is that this house is landlocked because nobody has any real solutions for this situation except the constant critiquing of ideas that have been proposed, which isn't anyone's fault, it's just the cards in the dealt hand. The only options here--to my knowledge--is an interior drain system.

 

Are you saying that your property is at the bottom of a 'bowl'?

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Pretty much. Looking at it from the outside, you wouldn't really think it because it doesn't show an obvious bowl landscape but once you see how water behaves during rains, you realize it needs grading but because of the property itself, it's just not very possible. The closest I might be able to do is take down a tree by the city street and then bulldoze the heck out of the land to grade down the street direction, but I'm not convinced it would be impactful enough to merit the money and effort.

I've attached 2 images: both basically show the house and the land it sits on. I'll try to find one that shows the rear of the home and lot, but these two might give you an idea of what I'm up against. The South face has the best options where grading is concerned but considering how my perimeter drain sits basically 7-8 feet below the driveway level, it's somewhat moot from what I can tell, which is why we decided to bring the water into the basement to be pumped out to the city rainwater drainage (the 2" discharge pipe currently runs through some crawlspace and travels underground from under the add-on master bedroom on the South side of the home).

Both images I was able to grab from Google Maps but neither show the 20' 4" solid PVC downspout extensions I currently have attached to the downspouts, with one being on the South corner of the porch and 2 being behind the home on the East side. The place that I get the most water is right there on the North-West corner: water tends to come in at a corner in the basement where the old wall meets up with new. Some of this is because the contractor made no effort to compact dirt or cement anything where the old block was exposed which runs underneath the porch. Instead, they simply dumped pea gravel down into the trench after putting a thin layer of tar sealer on their new walls whereby their masonry guy tried to seal everything as well as he could from the inside using some cut-to-size CMU along with mortar. So it's no surprise that water comes in right there and I'm currently trying to get a quote about how much it would cost to dig up the pea gravel and redo that as a worst-case approach, but it still wouldn't do anything about the water coming in as there's nothing that I think can be done about it from the outside.

from_street.jpg

from_street_2.jpg

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Would you consider a small rainwater drainage pond to which you could drain two swales that begin on either side of the driveway, encircling the house and draining into the pond?

Make the swales no more than 1 inch deep at the driveway, no more than about 10 inches deep where they dump into the pond. Perhaps 10 to 15' wide at the deepest point. Very mild, nothing ugly.

Make the pond about 12' in diameter and deep enough to alleviate your issues. Make the pond as far away from the house as you can, and as close to the city rainwater drain line as possible. Cut a level swale from pond to city rainwater drain line.

Edited by Marc
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Hmmm... I'd have to think about that. I'd have to swap no less than about 1 foot worth of pea gravel in areas above the perimeter drain to have a substrate I could use for something like this unless I opt to use some sort of drain pipe approach...but the dirt substrate would allow molding a swale shape to encourage water to sink into it. I'd have to think about the depth of the pond, too, because I can't see anything less than 3' working as I'm assuming this kind of system depends entirely upon gravity and grade to work well. Then there's the placement of the pond or ponds themselves: if I did something like this, a larger pond would have to go in the front yard directly to the West of the house as close as possible to the street (which would be close to 35-40' away from the home) with maybe a smaller one installed behind the house to the East as close to the alley drive as possible (which would be about 30' away from the house).

But basically, it sounds like your vision of this swale system consists of a "grassy trench path" that would be designed to channel surface water into said ponds, correct? If I did something like this, I'd probably opt for something that would transfer water better than that grassy pathway such as digging a 1 foot deep by 3 feet wide trench of topsoil completely out to carve a path that leads to the pond, then place tarp down on the exposed dirt path to prevent water bypassing this path... Then, I'd lay down pea gravel bed for a 4" pipe to rest on but then cover all of that up with the topsoil that was taken off (leaving a swale impression all along its path to encourage the water to sink into but due to the dirt covering everything, would appear as grass and not gravel--in time, at least, once the grass grows back).

I mean, I guess this is a possibility. But is there any difference between this approach and the installation of a few dry wells? If I dig the pond(s) deep enough to provide gravity incentive for any water to want to use, it could work, but it would only trap whatever is on the surface (doing nothing about any subsurface water that might still exist beyond whatever gets trapped in this). Also, assuming the water eventually dries up in these ponds, I guess I'd be looking at a bare spot out in the yard whenever the water dries up or are these supposed to appear as grassy sunken spots in yards after the water dries? Leaving only a visible swale (or pipe, if I chose to use one) leading into this sunken grassy spot?

 

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'Grassy trench path' doesn't quite cut it. A swale is like a ditch, only much more shallow and much more wide. Done correctly, you'll hardly notice it, but it'll drain the property. Did it myself years ago on my own property to carry water from the rear to the municipal ditch in front:

Edit: You could do a dry well...same thing.

 

 

3F8F0478-B8A2-4AE7-99C1-F74086279CBF_1_105_c.jpeg

Edited by Marc
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I see... If you did it yourself, how did you do it? If you hired someone, what kind of person did you hire to do it? Did it have that much of an impact on water and drainage to feel like it was worth doing?

When I think about doing that with my yard, it's hard for me to believe it would put a dent in the amount of water I sometimes deal with in my basement, but I'm not at all dismissing this as a possible option... I guess a lot of it just depends on how it gets graded and how much gravity it gets to use.

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5 hours ago, Wolf_22 said:

I see... If you did it yourself, how did you do it? If you hired someone, what kind of person did you hire to do it? Did it have that much of an impact on water and drainage to feel like it was worth doing?

When I think about doing that with my yard, it's hard for me to believe it would put a dent in the amount of water I sometimes deal with in my basement, but I'm not at all dismissing this as a possible option... I guess a lot of it just depends on how it gets graded and how much gravity it gets to use.

I ran a tight string along the middle at fender height (my tiller has fenders). I then cut a path the width of my tiller, removed the excess soil, then sloped the sides with tiller by swaying it sideways. Took two days. It's about 100' long, 12' wide. About 2 cubic yards of soil removed. Photo taken while standing in the ditch.

68A30E4D-1804-4C82-8271-A5EDF738B187_1_105_c.thumb.jpeg.5bc31e5af3d4730d1d47cfac07b37b22.jpeg

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I'm curious about any distinctions that exist between the swale + pond idea vs. French drain + dry well idea. The swale + retention pond sounds okay but it also sounds like it would be the most disruptive to a yard without providing the more efficient medium to transfer water. One difference I can see as being better with the swale + retention pond idea is that the final point where the water ends up would be open to daylight and more likely to dry up faster whereas a dry well would likely retain water longer due to its encapsulation and less air movement, etc... Both benefit from percolation, which is an issue with my yard due to it consisting of clay loam...

Regardless, the swale + pond would require my yard to undergo major landscaping. I'd have to take down a tree over in a corner in the front yard, perform some massive grading with the dirt, then install the actual swales + pond and that would be only the front yard (albeit the area which would benefit the most from something like this if it does anything at all). However, with a dry well--assuming it's fairly close to the same functionality one gains with the swale + pond--would be completely hidden under the ground and still enjoy the drainage you'd observe with the swales emptying into the pond, only better because it would likely use a more efficient drain line with tarp and pea gravel on top of that covering the pipe, etc.

With all these ideas being floated around, I'm almost tempted to consider taking tons of my yard out to be replaced with a better more percolating dirt in an effort to facilitate better absorption, only at a grade to motivate the absorption away from the house... I shudder at the cost of something like this.

But again, the pond idea would benefit from daylight + wind movement, thereby increasing the likelihood and speed of drying, or at least, I'm assuming... I'm just not sure what to do and I'm worried that I'd just be chasing my tail with these suggestions. But whether anyone on here likes it or not, I'm definitely doing an internal drainage system before I do anything else as part of that project is going to entail joining my two sump pumps together via the trench to incorporate redundancy that I don't currently enjoy. In other words, right now, my perimeter drain pump is on it's own circuit. So this drain system will join the two so that if one goes out, the other one can keep the drainage going.

I've got 2 water proofers and a plumber coming out to the house next week with another construction guy who did my 2 basement wall rebuilds coming out sometime after that. I plan on asking them all about these ideas to see what they say. I'm afraid they'll poo-poo it and say that it's unlikely to do much for me, especially considering subsurface water issues I have (i.e. - high water table). Not saying they'd be right to poo-poo it, but just saying that this has been a common reaction to similar ideas when they're floated to these kinds of guys that have been out to my place before to talk about things like this.

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Removing the tree may aggravate the issue. In the summer, it removes a large amounts of water from the ground.

If you think you'd need to remove massive amounts of dirt, You've missed the point. Its mostly about redistributing dirt.

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Maybe I did misunderstand that about the swale... But even if it's about moving dirt around, if I did it, I'd still take the tree out that I have in mind because it's a dying maple, a sign that it's not getting enough water as maples seem to be trees that thrive on wet grounds.

So if I did remove the maple, that would open some options up for grading and I guess that's why I instinctively blended that *optional* component to your swale concept. My apologies on that--I tend to merge ideas but assume the final product is the original concept when I think things through too quickly.

But remove the tree or keep it, it's about moving dirt around to form little passages for the water to be transferred through. Check, got it. But the thing is that, if I do remove the tree by the street, I could lower that area enough to potentially coerce the water down toward that direction, at least on that side of the property. But even doing any of the swale concepts, it's still going to be way more than I can do on my own and pickings are pretty slim for contractors who do this kind of work around where I live. We mostly have what I call "pretend landscapers" who specialize in conning 80-somethings into mowing yards for thousands of dollars and calling that landscaping. To me, whenever I think of landscaping, I think of exactly the things we're talking about, but since that usually requires machinery or manual labor beyond planting trees or cutting grass, you just don't see many people who do that kind of work. If they do, they're usually called excavators (at least, they are in my area), and pickings for those types are pretty slim, too, at least for good ones.

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