Interior French Drain???

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#1

Originally Posted By: bsmith
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I got a call yesterday to do a pre-listing on a hillside house owned by a contractor. The lower level of the house is under grade on one side. The realtor mentioned that the owner told her that the house has a “controlled leak” and an interior french drain. Since I am not that experienced (and here on flat long island we don’t see very many “hillside” houses) I was wondering if any of you have had experience with “interior drains”?



Thanks, Bill Smith

Smith Home Inspection

#2

Originally Posted By: jpope
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, so I divert the water and tell everyone;


"It's supposed to look like that!" ![nachi_sarcasm.gif](upload://6HQh6KbNiD73gqTNQInjrR2zeJw.gif)

Be careful. It sounds like somebody wants you to co-sign their bullshht.

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

#3

Originally Posted By: bsmith
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Jeff-


I agree with the co-sign comment (did I mention that he is a contractor??). I also agree with the “leak that can’t be fixed” part. I’ll know more tomorrow. I’m doing this as a favor to the agent and as an intro to the agency. They already have an offer on the house and she wants to avoid deal-breakers later on. I’ll have to be more thorough than the buyers inspector. I haven’t gotten any work from this agency before so it’s worth the effort.


Thanks for your reply.

Bill Smith
Smith Home Inspection

#4

Originally Posted By: nlewis
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Bill,


This type of system is very common in NJ. There is a gap at the interior floor at the perimeter of the basement. The system doesn't stop water from entering the basement.It collects water entering the wall/floor joint area and directs into a sump pit. Think of it as a de-watering or management system instead of a water-proofing system. Holes are sometimes drilled into the bottom of the wall to allow the water to drain through the foundation instead of trying to keep it out, which would cause damage from hydrostatic pressure. Over time, the stone in the drain system can get clogged from silt or organic matter, if there is alot of water running through the system. Generally, installers give a lifetime warranty on the drainage part of the system, not the pump.

There could be a natural spring near the foundation. If there is enough, constant water flow at the foundation, the footing could be undermined. It might be wise to get a second opinion from someone like a soils engineer.

#5

Originally Posted By: roconnor
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Bill,


An interior french drain system should consist of perforated pipes run below the floor around the perimeter of the foundation along the inside face of the wall, which then discharges into a sump pit/crock with an electric sump pump or a gravity drainage system. The pipe may be below a slab or there may be a ring of gravel around the perimeter ? but it sounds like it's may be in finished space and therefore covered. Penetrating water is then directed into the pipe to the sump pit, and may be pumped out with a discharge pipe or directed into an underground drainage system.

These drain systems are used sometimes in the Long Island area ... usually for areas/sites with seasonally high ground water, perched ground water, or underground streams. They can be used sometimes to fix a wall leak from rainwater, but that?s not always the best solution (particularly for a finished space) ... which is to prevent the water from getting inside to begin with if possible. Depending on the situation, that may involve fixing/sealing any cracks/seams and installing waterproofing and drains on the outside.

Check the site/roof grading and drainage, and if you see a sump pump wet test it for operation and check for silting/clogs. Plus look for signs of continued water penetration or damage. The "controlled leak" fix may be a home sale band-aid that could still be allowing damage.

I noticed that we are actually pretty close, so if you need an engineer for a further evaluation feel free to drop me a line ... It's one of my specialty areas, along with general site, foundation, and structural evaluations and repair designs ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

#6

Originally Posted By: bsmith
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OK- I did the inspection this morning on the “controlled leak”. It is an ongoing leak that has been there as long as the house has been there (or so the owners say). The west wall of the basement seeps water whenever there has been rain. We have had quite a bit of rain so the wall was quite wet. The french drain the realtor spoke of was outside (and unfortunately higher than the level of the water problem). The owner suspected that the drainage problem was coming from his neighbor’s dry well. I suggested a dye test to see if that was true. I also suggested several weep holes along the bottom of the wall to alleviate hydrostatic pressure. At least then he could deal with the problem with some degree of control. Of course the best solution would be an exterior fix but he wants to sell the house with a minimum of expense and bother.


Thank you both for your responses. Robert, it’s good to know there is a Nachi P.E. nearby. Please send me contact info so I can refer you if the situation arises. I used to live in Syosset on Kathleen Dr.



Bill Smith
Smith Home Inspection

#7

Originally Posted By: roconnor
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Gee, the homeowner wants to sell with minimum expense … go figure … icon_rolleyes.gif


Sounds like its actually a supplementary exterior foundation drain installed up higher to try to intercept the water flow (if it really was done), but it didn't work. Not really a "controlled leak" since it didn't stop or collect/discharge the water infiltration. Sounds like they were trying to sell you on it before you even saw it ... go figure ... ![icon_rolleyes.gif](upload://iqxt7ABYC2TEBomNkCmZARIrQr6.gif)

Could be a lot of things so be careful with what you report/recommend until the actual source/cause of the leak is identified, because it may or may not help ... and may even hurt the problem. For example, weep holes along the base only allow more water to penetrate with nowhere for the water to go, and are only used sometimes with a true "interior french drain" to relieve hydrostatic pressure, if that really is an issue. Dye testing may be a good idea if the neighbor's dry well really is suspect, but that's an outside shot based on past experience.

Just "observe and report", and be careful what you report as you know it's most likely going to be flagged by at least an NACHI certified buyers inspector ...

Glad we could help and keep in touch.

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong