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I bought a house with a french drain already installed but it seemed to get a couple wet spots around the house especially after a heavy rain.

I dug up a portion of the slab and saw that there werent any weep holes and the slab was almost cemented to the footer. See pictures. I redid sections of 2-3 feet wide to allow drainage and spaced it 5-7 feet apart to minimize the excavation volume. I drilled weep holes as far down as possible all around.

This was a remodel house where all the walls are new except an old front wall. Most of the places nothing comes out of the weep holes except the old front wall where some water is draining with every rainstorm.

Does anyone think I need to redo the whole thing?

interior french drain

does it look to compact or messy and is it low enough

old wall after drilling weep holes

new wall after adding weep holesenter image description hereenter image description here

  • I’m not sure I understand what I’m looking at. Pic 1 is looking down on the exterior of the wall? Pic 2 clearly shows the wrong type of rock was used as backfill around the drainpipe plus there is no filter fabric, so the pipe will plug and be useless. (This is on the interior of wall?) Pic 3 and 4 is exterior of wall? (...because why would you drill interior of wall?) – Lee Sam Nov 20 '17 at 1:18
  • As Lee Sam says, that's either the wrong kind of stone or the system has become saturated with silt. It isn't clear how water from the weep holes is supposed to get into the drain channel. There are after-market solutions for above-floor weep holes. The ones I've seen involve a floor drain or sump pit where the water can enter the system, and a plastic channel that goes between the wall and the floor that keeps the water sealed off and directs the flow to the drain opening. – fixer1234 Nov 20 '17 at 2:05
  • All those pics are interior, there's actually a pipe in there, with fabric on it but it's covered in soot/dirt. I agree it should be filled with 3/4 clean but it's not. Like I said, I cut on small sections 2feet by 2 feet and clean it up and put 3/4 clean like it should be, and did that every 5-7 feet apart. Cutting out everything is a lot of work. – Vk10000 Nov 20 '17 at 2:27
  • So you drilled “through” the exterior wall at its base? Wouldn’t this allow water to come in through the holes on top of the slab? I don’t get it... – Lee Sam Nov 20 '17 at 5:38
  • @LeeSam, This is an interior drain system. The drain is under the basement floor and the weep holes are from the basement into the cores of the blocks. – fixer1234 Nov 20 '17 at 6:16
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What Lee Sam's answer describes is the right way to do the job on new construction. Everything is already exposed. However, it's REALLY an expensive, messy, long-term job to do after the fact.

Excavating the foundation to the footings involves a really deep and wide, reinforced trench, moving a lot of soil. In addition to the work of accessing the foundation wall, it will destroy the surrounding yard. When you're done, putting the soil back will start a multi-year process of settlement and regrading, landscape cleanup, etc. In addition to the drain channel, you need to clean the foundation wall to examine the condition of any waterproofing and to apply any form of barrier.

In a case like yours, where the foundation walls are hollow-core blocks, it's much simpler to retrofit a solution inside the basement because everything you need to do can be done right below the basement floor. You can cleanly cut away the access area with a concrete saw, and reseal the area with concrete when you're done. It does create a mess, though.

You've been trying to fix small sections, but the job can't be done right in that manner. The existing system is too silted up to be useful, and you don't have a good way to drain the walls into the system. My recommendation would be redo the interior system. Bite the bullet and do the whole job correctly. Then it will be done and be permanent.

I had this approach done on a house of my own and it was a successful solution. Ground water, rising with a high water table or collecting around the foundation, collects in the interior drain the same way it would with an exterior drain. Water entering the foundation wall from the surrounding soil drains from weep holes in the hollow cores into the system. You generally use a sump pump to discharge the collected water well away from the foundation.

A key element missing from your attempt is getting water from the weep holes into the system in a way that is sealed from the interior living space. I found a good description online of the right way to do the job (website of the aquaGUARD waterproofing company). Disclaimer: I know nothing about this company other than their web site has a good description. Some excerpts:

trench

This part you already know. However, you really need to do the entire perimeter at once rather than a small section at a time so that you can effectively clean out the old material and put in a properly graded pipe and clean stone. An integrated wall treatment is involved, and that needs to be done before replacing the concrete.

drain pipe

The pipe, stone and weep holes are the next step.

membrane

This is your missing step. An air gap membrane is applied to the interior wall, then extends over the footer and drain pipe. This completely seals any water behind and under it and channels water from the weep holes into the drain pipe. The new concrete goes over this membrane.

There are a number of membrane styles. The one used by the company that created the web site is a heavy dimpled plastic sheet that is flexible enough to bend over the footer but strong enough to support the new concrete without the air channels collapsing:

air gap membrane

To finish the interior space, you can cover the membrane and there is no sign of the system except for the sump pump:

sump pump

Possible Alternative

All that said, given the point your project is at, I might be tempted to explore another solution because you don't have much to lose. If it doesn't work, you could rip it out and do the job right. I'm referring to "baseboard" drain channels. I have no idea how good, reliable, or long-lasting they are, but it is a simple add-on to what you've created that doesn't involve busting up any concrete (and it does nothing for any remaining bad drain pipe in your system; it only deals with your weep holes).

baseboard channel

There are a few styles on the market. Basically, it's a plastic channel that you glue to the floor, and sometimes the wall. It covers the cove where the weep holes are and seals the water inside. You run the channel around the perimeter and it drains into the sump pump. This particular one is from this web site (just an example, no personal knowledge).

A similar system sold for DIYers:

Seal Once

I'm a bit skeptical, but the cost is advertised at $6/ft, and at least it's a better solution than leaving the exposed weep holes. Worst case, you waste a few hundred dollars without changing anything that affects doing the job the conventional way later, if needed.

  • +1 for a Good method, but the weak link is having the water channeled indoors. Any break in the laps of the “air gap material” or blockage that causes the water to back up and spill over the top of the membrane, will create real problems. – Lee Sam Nov 21 '17 at 5:07
  • Oh, and I’d be afraid of that moisture turning to tons of mold lying along the base of the wall...especially in that last illustration. – Lee Sam Nov 21 '17 at 5:10
  • @LeeSam, yeah, those baseboard system's scare me (for the reasons you mentioned and others, like the ability to get a good permanent seal against an uneven floor). The only reason I mentioned them is because in this case, it might be an improvement over the current condition of just leaving the weep holes and water exposed, and it's relatively cheap to evaluate. – fixer1234 Nov 21 '17 at 5:29
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So moisture is either coming up from below (a rising water table) or its coming from the surrounding ground water in the saturated soil.

If it comes up from a rising water table, it will enter the living space from below through the crack between the foundation wall and slab.

If it comes from the surrounding ground water, it COULD enter the living space through the wall, especially if the exterior side of the foundation wall is not sealed properly.

Either way the moisture enters the living space it will need to be collected and disposed. I think the best way to collect it is on the exterior side of the foundation wall in drainrock and a perf pipe laid 6”-8” below the interior basement slab.

To keep the subsurface water from seeping through the wall, I recommend installing a moisture barrier on the exterior side of the foundation wall and install a 2” thick plastic mesh on the wall to allow water to flow down to the perfect pipe. If dirt is allowed to be backfilled against the wall, the dirt could hold the moisture giving it a chance to seep through the wall.

Once collected it needs to be disposed by extending a solid pipe over an embankment or in a collection well and pumped away.

This may be the most expensive method of solving the problem, but it’s sure to work.

  • I ended up having someone excavate around exterior of house and having a company spray rubber on the exterior. Now my contractor plans to sit the drainage pipe on top of the footer instead of on the side is the best way to do it? Also how much stone is enough, if he puts 12” all the way up is that enough or should it be wider? – Vk10000 Jun 21 '18 at 2:19
  • @Vk10000 The perf pipe MUST be below the slab. If the perf pipe is above the joint between the footing and the wall, water can enter the basement. Yes, 12” of drainrock around the perf pipe is adequate. I’d extend the drainrock up to the top so water can easily run down to the pipe. However, don’t let the rock touch the membrane. It could puncture the membrane. I’d put a “protection board” on the membrane first then back fill with drainrock. – Lee Sam Jun 21 '18 at 3:39
  • Thanks, I added a picture of what it looks like now. They sprayed the rubber coating all the way down and over the top of the footer and added some kind of fiber glass board or wool like stuff. I expected a hard plastic material. So it seems sealed between the joint where the blocks touch the footer bit could be wrong. If he just puts the pipe on top of that footer where you see the black coating would that work? It’s about 4 inches below the top of the slab since the slab sits on top of the footer. – Vk10000 Jun 21 '18 at 4:07
  • @Vk10000 If it’s about 4” below the slab, it should work. – Lee Sam Jun 21 '18 at 4:32
  • Added a picture of the backfill – Vk10000 Jun 27 '18 at 2:52

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