Home>Discussions>EXTERIORS>French Drain Clogged?
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Kevin Amter
French Drain Clogged?

I have a post and beam style house built in 1965, with no gutters. Adding them would detract from the Frank Lloyd Wright aesthetic the original architect envisioned. The house also has a very small 10' x 30' boiler room with a French drain running down the back of the foundation. I'm guessing the drain runs the entire length of the house, approximately 300 feet. During extremely heavy rains the boiler room floods slightly. I have dug down to the top of the original french drain along the boiler room foundation and without taking it apart, it appears to be in perfect condition. I then double coat water-proof sealed the foundation down to the top of it. Approximately 6 - 12" below the surface - depends on slope of house. I also water-proofed the seams inside the boiler room.

We just had a long hard heavy rain and the boiler room leaked again. Not as bad as before, but it leaked.

I've read due to the age of the French drain it may be clogged. How do you unclog one?

Also is there something else I should do, besides gutters to prevent this in the future?

Thank you.

Re: French Drain Clogged?


I also have a post & beam house that's much older than yours, & they told me the same story years ago---that it's not designed for gutters---baloney!

Without roof gutters, a LOT of water is going to accumulate around the foundation, possibly rot the sills & no doubt leak into the basement.

One of the best diy projects I ever did was to install vinyl gutters on everything---they look great---I even fed the downspouts into a 4" plastic underground drain system with catch basins that goes into a combo underground storage tank & drywell 30' from the house in an area that drains very well---all the items are carried by HD/Lowe's and are low-cost.

I have plenty of free water for plants, veggies & hedges in the summer, & tons of water are invisibly whisked away from the house during each rain storm.

It's a shame you didn't do a thorough sealing of the lower foundation when you dug it up--it may or may not be a clogged french drain---you'll have to do a little detective work until you pinpoint the exact cause.

Sometimes french drain installers go to the surface at one end with the french drain so you can easily run a jet nozzle down it on the end of a garden hose & clear any clogged mud or sand---look around the yard near the foundation for this---also look around near the foundation for a CATCH BASIN that leads into the french drain--a CB is designed to catch the inevitable sand that flows into the drain system during a rain storm & clogs it up.

The CB has a removable cover so you can scoop out the sand & clear it up to get the system flowing again.

Make sure your yard is PITCHED AWAY from the foundation slightly, this will force the rain water to flow away from the building.

There's a joint between the concrete footing & the foundation wall that has to be sealed (black roofing cement is as good as anything), then a wide length of plastic sheeting is attached to the fresh roofing cement for a good seal.

If there is no access to the french drain from grade, you would have to dig down & break open one end of the french drain while you run the jet garden hose nozzle thru to make sure you have a good water flow---the flow from the FD should go to a dry well (hole in the ground covered with rocks) that has good drainage so the water is not allowed to build up pressure against the foundation---the hole in the FD can be easily patched with a piece of plastic pipe & mastic, or replacing a small section of the broken pipe.

The french drain should have a FABRIC SOCK (Lowe's) that fits over the 4" drain so dirt & silt is not allowed to get in & clog up the drain pipe.

Hundreds of gallons of water come off a roof during even a mild rainstorm---it's got to be diverted away from the house or problems will occur.

White vinyl roof gutters, downspouts & connectors are attractive, surprisingly low cost, easy to install---I think they look great--you can always remove them easily sometime in the future if you decide you don't like them.

I used green-colored deck screws (won't rust) to do the attachements with a drill & deck screw attachment---some low cost aluminum/vinyl 10' strips of flashing may be needed at the shingle edges to make sure the water falls into the gutters.

Google such phrases as "soggy yard", "french drains", "catch basins", "dry wells", "keeping water out of basements", etc.


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