Water intrusion into finished basement. Interior drain vs French drain.

[u/Xarick]

During very heavy flooding rains here in the pnw water seeps through the back wall and then begins to come up from around the pipes that go through the concrete. In the 14 years I have had three times where water has flooded in and I have been bailing to save my interior. Usually it is just a trickle.

I have now gotten two bids. One is $12k to dig out 10" along the interior of our back wall, out in a drain, put in a sump and then pipe the water out to a dry well. I am told this guaranteed for 10 years to not leak, but requires me to redo the interior of my home along the wall.

The other is to put a French drain in about a 3' from the foundation wall, and daylight it on the side yard. About $5k. The French drain only goes down about 18" which seems shallow to me, but he said that is normal for French drains.

I don't know what to do as one is very intrusive and one I am not sure will work.

Do any of you have experience or advice with this type of stuff?

[u/ADDSquirell69]

French. You stop the water before you need an internal drain.

[u/indyarchyguy → u/ADDSquirell69]

Exactly. The first doesn’t solve the real problem. And it still allows water to breach the wall. The French drain addresses the actual problem head on. When we renovated and added on to our home, I put the drain about 12” from CMU wall….and about 24” down. The people that owned the house prior to us put in the internal drain and sump. I could literally see the water seeping through the face of the CMU. French drain has been in for 8 years. The sump remains dry to the bone to this day.

[u/ADDSquirell69 → u/indyarchyguy]

Redirecting all of your downspouts 1% grade away from the house as well as a French drain that daylights 15 ft from the house you'll be lucky to ever hear the beep from the sump pump going on. I heard it once in 5 years.

[u/devilandapardo]

Personally i have always felt like interior fixes for groundwater flooding are approaching the problem backwards. I do not want to invite water into my home and deal with it after the fact.

Deal with the water on the exterior through gutters, grading, swales, drains (French or otherwise) and when those options are not practical or have been exhausted, interior options are the last resort.

[u/Patrol-007]

French drains outside also don’t work when the frost line is 4’ (along with frozen sump hoses)

[u/littleGreenMeanie]

Sounds like hydrostatic pressure from below. Do you have retaining walls near your house? It sounds like the water is getting trapped during floods under your house then the easiest path is up.

I'm my case I had it coming from the walls and roots. My fix was to trench out the interior printer of my basement, put up waterproof membrane, install big o piping and a sump pump system. Very expensive. If you have a healthy body, do it yourself. Save at least 10 grand. the company was terrible. I got 3 quotes choose the most professional. They demanded full payment 1 business day after the job was done, threatened to send collection agencies and put a lien on my house at that same time and gave me a lot of problems during the entire project, but it's been dry since.

I have a block foundation. Never again. The right way is to have it around the exterior of the foundation so the water never touches your foundation. In your case, with it coming from below. I'm not sure what the solution is.

[u/ssllee1967]

Sounds like a high water table issue, not sure the French drain is going to actually solve your problem. We dealt with a similar issue for years and finally had the interior drain work done. We have had zero issues since. We cut the interior finished walls 24 inch high to allow for the work and reframed from there.

[u/EstablishmentFar6582]

18" is way too shallow for a foundation drain, especially in the pnw with our clay. that's gonna do basically nothing when the water table rises during those heavy storms.

the interior job is disruptive but at least it addresses the actual problem of water coming up through the slab. had a similar situation at my place and after the third flood I just bit the bullet on the interior drain, haven't had issues since

the french drain guy sounds like he's selling a trench that'll move surface water and calling it a day