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Block Wall Foundation built on Poured in Place


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Have 1920s house with a leaky basement. I have demod out the drywall and insulation on the interior side of the home.

The plan was to excavate a portion of the west elevation of the house, seal wall with liquid applied vapor barrier, and install a french drain that empties in to the far end of the front yard.

In the process of excavating I found out that foundation was built out of an old poured in place concrete wall with cmu block on top of that. Assuming at the seam is probably were my leakage is happening.

At a few of the high water path areas the concrete has spalled off. Looks like a mixed on site, large aggregate, pour mix...

Any concerns from a structural stand point that anyone could see? There is one small vertical crack in the wall but the wall in all is plumb and straight. I'm I taking the right approach as far as addressing the water issue? Any recommendations from the pros? First time home owner here.

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Another thing to add is I found an old clay drainage pipe. Looks like at one time this is what the down spout for the gutter? Once I pulled the first section off the line was bone dry and clear. Ran a hose down it for 20 min and it never backed up. Couldn't find any evidence of it exiting in the yard or curb side. Wonder where it's going?

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We have owned the house for less then a year. The gutter system is cleaned regularly. But the corner of the foundation has the most water damage. Probably gutter issues in the past with previous owners.

Since we have owned it basement has only leaked after numerous days of heavy Oregon rain.

First, did you rule out or correct all potential problems with gutters, downspout terminations and site grading? These things make up the majority of wet basement problems.

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Where exactly do the downspouts terminate? How far from the foundation wall? Are there any roof valleys that cause heavy rain to shoot over the gutter and spill on the ground next to the foundation? Does the grading in the area of trouble slope adequately away from the house such that no surface water moves towards or along the walls?

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Hard to tell from the photos, but its looks like you may have excavated below the bottom of the foundation wall at some areas. If so, that is not a good practice. There is a greater potential for settlement, especially if the soil below the foundation gets wet.

Regarding the corner with the concrete, not sure what is going on there. If the foundation has not been a problem so far, it is probably ok. Backfill with granular soil or crushed stone and don't get too agressive with compaction. Make sure you are draining the water away from the foundation, which is sounds like that is the plan.

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Blake seem to be doing fine to me. Looks to be on the right track.

I don't see any concerns with the foundation, especially since there's no indications of significant issues after almost 100 years of service.

Once in a while, folks come here who actually know what they're doing.

Marc

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Would I be crazy to try and tie a french drain along the foundation into that old clay pipe? Would save me a ton of time not digging a 75' trench through the front yard.

At best it's unpredictable, at worst it fails at some point. Video scope it to see where it goes. If you can't nail it down with certainty, dig the trench.

Back fill in lifts with stone alongside the foundation.

After that, keep going. Oh, wait....what vapor barrier?

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Agree with Kurt, I would get a plumber with a sewer cam to inspect the line for problems and find the outfall. If it's in good condition and slopes to daylight, probably OK to use. If not. I might dig right on top of it, remove it, and replace with plastic. Find a high school kid on a Saturday and tell him $1/foot or something like that.

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Had planned on using Drylock Extreme

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Will investigate the old clay drainage pipe a little more this coming week. Unfortunately with the holiday we have a bunch of family in town.

Thanks for all the input so far guys.

At best it's unpredictable, at worst it fails at some point. Video scope it to see where it goes. If you can't nail it down with certainty, dig the trench.

Back fill in lifts with stone alongside the foundation.

After that, keep going. Oh, wait....what vapor barrier?

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Have 1920s house with a leaky basement. I have demod out the drywall and insulation on the interior side of the home.

First, some overview. Most 1920s houses in our area have "leaky" basements. That's a *normal* condition for a house from that period. You must understand that in the 1920s no one ever expected your basement to be dry. The builder didn't build it to be dry, and the owners didn't expect it to be dry. The whole notion of a dry basement is a modern conceit. Before you go any further, it's essential that you understand this. People often think that their basement is leaking because there's a flaw somewhere and that if they can just find and fix the flaw, the basement will be dry. That's not the case. The entire interface between the basement and the earth is not set up to keep out water.

The only effective way to keep water out of a basement is to give the water somewhere else to go before it reaches the basement. Before you do that, you must understand that most water in basements rises up from below, not down from above, or in through the sides. The soil around the house slowly becomes saturated until it can't hold any more water and then the water oozes into the basement. Any drainage that you install above the level of the basement floor is going to have a limited effect or no effect.

The plan was to excavate a portion of the west elevation of the house, seal wall with liquid applied vapor barrier, and install a french drain that empties in to the far end of the front yard.

That will only work if the drain tile is installed below the level of the floor. When doing this it will be important to not undermine the bottom of the foundation wall. Excavate down to the bottom of the wall, then cut a deeper trench at the bottom of the first one but out about 12-inches from the wall. This way, the soil immediately below the foundation remains undisturbed.

Use filter fabric and plastic drain tile. If you're using S&D pipe place the holes facing down. Then backfill the whole thing with clean round rock. If you want to put a waterproofing material on the wall, fine. But it's not necessary because water will never get to the wall in the first place.

As the water level in the soil rises, it encounters the drain tiles before it reaches the level of the basement. The water flows into the low pressure area in the drain tiles rather than pushing into the higher pressure area under the concrete.

In the process of excavating I found out that foundation was built out of an old poured in place concrete wall with cmu block on top of that. Assuming at the seam is probably were my leakage is happening.

That's an extremely rare construction method in Portland - especially for the '20s. I'm not sure what's going on there.

At a few of the high water path areas the concrete has spalled off. Looks like a mixed on site, large aggregate, pour mix...

Something's very odd there. I don't know what, but that looks more like a repair than original construction.

Any concerns from a structural stand point that anyone could see? There is one small vertical crack in the wall but the wall in all is plumb and straight. I'm I taking the right approach as far as addressing the water issue? Any recommendations from the pros? First time home owner here.

Be very careful with the original concrete. It's very weak. You don't want to go bumping it with a backhoe.

You're going to want to finish this up really quickly before the rains start in earnest.

While you've got the trench open, install new plastic underground drains for your downspouts. It's best to not continue to channel them into the clay tiles. Those things often functioned as a watering system for the basement.

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First, did you rule out or correct all potential problems with gutters, downspout terminations and site grading? These things make up the majority of wet basement problems.

The majority of wet basement problems in our area happen when the soil immediately next to the foundation gets saturated with water. After that, the water just flows into the basement. If you don't want water in the basement, you have to prevent the soil below and next to the basement from getting saturated - because if it does get saturated it will come inside no matter what kind of waterproofing you apply.

Fixing leaking gutters, poorly terminated downspouts, and poor grading can help to reduce the likelihood of saturated soil, but it can only go so far. In our area, even if you took every drop of water from the roof and sent in into the next county, the soil can still become saturated.

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Another thing to add is I found an old clay drainage pipe. Looks like at one time this is what the down spout for the gutter? Once I pulled the first section off the line was bone dry and clear. Ran a hose down it for 20 min and it never backed up. Couldn't find any evidence of it exiting in the yard or curb side. Wonder where it's going?

It's probably going into a dry well on the property. You can run your hose and all of your neighbors hoses into it for a week and you won't see a thing at this time of year. But once the ground becomes saturated and the drywell starts to fill with water (late January most years), it will become less effective. It all depends on how large and how deep it is.

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Hard to tell from the photos, but its looks like you may have excavated below the bottom of the foundation wall at some areas. If so, that is not a good practice. There is a greater potential for settlement, especially if the soil below the foundation gets wet.

He'll have to excavate below the wall if the system is to be effective. But he shouldn't excavate below the wall *next to* the wall. He should stay about a foot out from the wall.

Regarding the corner with the concrete, not sure what is going on there. If the foundation has not been a problem so far, it is probably ok. Backfill with granular soil or crushed stone and don't get too agressive with compaction. Make sure you are draining the water away from the foundation, which is sounds like that is the plan.

The best backfill in this case will be washed rock, either round or sharp, and all of about the same size. You don't want fines in there because you want water to just flow straight down through it. If you use 1-1/2" clean rock, no compaction will be necessary or, indeed, possible.

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Would I be crazy to try and tie a french drain along the foundation into that old clay pipe? Would save me a ton of time not digging a 75' trench through the front yard.

Don't use the old pipe. The overwhelming likelihood is that it leads to a dry well. If that well were to fill with water, it could send water back into your drainpipes and actually push water into your basement.

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Send a check to Jim Katen for the free advice.. I'm ditto... Be careful you do not undermine the foundation... the 'fines' in the soil at/under the foundation wall could migrate out into your drainage system, leading to undermining and damage/differential settlement to your foundation walls... Filter-fabric is a must here.. .as is clean gravel.... and ideally, you'd be going to 'new' drainage out front... get that line cam-scanned and find out what the terminus is.. you have your work cut out for you....!!

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Couple of notes....

Don't worry too much about digging next to the footing. The thing isn't that delicate. People talk like if you disturb the soil next to the footing for a few minutes, the house falls down. No, it won't. If you dig down, get tile installed, and backfill in short order (a work day, even several days if it doesn't rain), it'll be fine. Go right next to the footing; that's where you want the drain tile. One shovel full will tell you what the dirt's going to do. You're not dealing with a souffle' fer chrissakes.

Don't use big stone for back fill. All it does is fill up with dirt "fines" that folks are so worried about. Use a crushed stone (not pea gravel!), #67, maybe #5, washed, no fines. #67 is easier to bank in the lift than #5 or the big stuff (#1).

I've never used UGL Drylock; don't know anything about it other than its a waterproofing paint, not thick sealant, and it's only $60 for a 5 gallon bucket. Sounds like handy homeowner stuff. On your lumpy dirty foundation, I doubt it would do anything.

With it all open, I'd torch a mod bit membrane to the wall and run it down to the drain tile. Cheap, reasonably fast, and entirely effective.

If you want to get smart, get some Miradrain, or a product like this, and you can do away with the stone backfill.

Ditching stone is a great improvement for the DIY'er. Not having to hump crushed stone around a job is easily worth the extra expense of Delta or Miradrain. If you ever try to move crushed stone by hand (shovel), you'll learn what I mean.

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