Determining if a french drain will work or not?

[grossgary]

I'm not well versed in this stuff at all and just spent an hour reading other threads here and many hours reading online over the past couple weeks.

Water leaks where the block meets the slab, on the uphill side of the foundation of course. With one heavy rain it'll get damp in the corner. I've checked the gutters, doesn't seem to be run-off related.

With multiple heavy rains/melting snow it'll take on a lot of water.

I know nothing about the soil, etc. There's a very steep slope behind the house where the leaks are. We have a large deck so digging the foundation out is undesirable.

Is there any chance that a french drain - about 10 feet from the house due to the deck - will keep our basement dry? That would be easy as there's a drainage creek over at the side of the property not far away and an easy grade to work with across the property.

Worth a shot?

 

[ihuntbear]

I did that to my property.Dug a ditch about three feet deep running to the side of the propery and filled it with drainage stone .works great:thumbsup:

 

[VABlue]

Its certainly worth a shot, especially if it won't be too expensive. Your problem, though, sounds like ground water seepage, not so much surface runoff. So a french drain may be too high vs where the foundation leaks. More info would be good - is the basement finished, or can you put a drain around the inside bottom of the foundation (in the crawl space)? Can you get to the foundation wall and repair any leaks you see?

 

[grossgary]

thanks guys.

I did that to my property.Dug a ditch about three feet deep running to the side of the propery and filled it with drainage stone .works great:thumbsup:

were you having leakage before?

Your problem, though, sounds like ground water seepage,

what makes you think that and is there any reasonable way for me to try and determine?

as long as there's a chance it will work, i'm okay with giving it a try. of course i'd like to know for sure but i don't see any way for me to make that determination. foundation is completely buried on the back side of our multi-level house so it'd be at least 8 feet of digging, not to mention ripping out the deck.

 

[/pine]

A french drain will work to move water anytime there is a negative pitch to the pipe (1/8" -1/4" /foot is nominal) and the surrounding earth is not already saturated

 

[dave1949]

I think it would be worth a shot for sure. Especially since you have a good place to run the drain to.

I would go deeper than 3' though. A deeper trench will intercept ground water moving down the slope and catch surface runoff water at the same time. The design of the drain needs some thought. But I picture it as two drains in two trenches. Nearest the house on the slope, a trench down deep, and and up slope from that, a section to deal with the surface runoff. I would use a drain pipe in each with plenty of washed stone around the pipes. Both should be covered with filter fabric above the washed stone, and it wouldn't hurt to use the drain pipe with the 'sock' either. Both need to be well below your frost line. The one nearest the house I would put in deep as I could. A basement foundation should have a drain pipe laying beside the footer - sure you don't have one that got plugged?

Since you don't need to go far, and the pipe and stone are relatively inexpensive, the money will be in the digging of the trenches. It won't make much more of a mess to do two than one.
Dave.

 

[grossgary]

thanks for your replies.

It won't make much more of a mess to do two than one.

that is a really good option in this situation.

more than 3 feet and it'll be lower than the creek bed i was going to drain too. but i could "turn" the drain and follow the creek bed until they meet up if i want more depth.

based on your suggestion i'll try and go deeper, even if that means making a turn. i can go as deep as i want if i want to keep digging and following the creek bed longer. more digging and butt loads of stone are the only obstacles.

A basement foundation should have a drain pipe laying beside the footer - sure you don't have one that got plugged?

i have no idea, i don't know anything about that stuff, i barely know what you're talking about and i've even laid block before (only as a helper and many years ago).

we have a "drain" in the middle of our basement floor. had someone come snake it with a video camera device and it drains to the creek bed i'm wanting to drain to. i would guess that this drain might be connected to things you're referring too? the two drainspouts/gutters on the creek bed side of the house go through concrete (sidewalk) into the ground. I would guess those are also connected to that same drain pipe.

So i'm guessing if there's some kind of drain pipe then it's connected to that. but i don't think it has any kind of access, do they usually have some kind of access to clean?

thanks again all, it is really refreshing getting some feedback from folks that know and have done it. oh - and Dave I'm headed to Maine in exactly one week for a vacation (don't let your disapproval of tourists keep you from helping me though!??!).

 

[dave1949]

thanks for your replies.

that is a really good option in this situation.

more than 3 feet and it'll be lower than the creek bed i was going to drain too. but i could "turn" the drain and follow the creek bed until they meet up if i want more depth.

based on your suggestion i'll try and go deeper, even if that means making a turn. i can go as deep as i want if i want to keep digging and following the creek bed longer. more digging and butt loads of stone are the only obstacles.

i have no idea, i don't know anything about that stuff, i barely know what you're talking about and i've even laid block before (only as a helper and many years ago).

we have a "drain" in the middle of our basement floor. had someone come snake it with a video camera device and it drains to the creek bed i'm wanting to drain to. i would guess that this drain might be connected to things you're referring too? the two drainspouts/gutters on the creek bed side of the house go through concrete (sidewalk) into the ground. I would guess those are also connected to that same drain pipe.

So i'm guessing if there's some kind of drain pipe then it's connected to that. but i don't think it has any kind of access, do they usually have some kind of access to clean?

thanks again all, it is really refreshing getting some feedback from folks that know and have done it. oh - and Dave I'm headed to Maine in exactly one week for a vacation (don't let your disapproval of tourists keep you from helping me though!??!).

Hope you enjoy your visit to Maine. Not many tourists in my area. Used to live in Wells, ME; which is a tourist area in the summer. Where are you visiting?

If the creek bed is down three feet, I don't have this pictured correctly. I thought your basement was fully in the ground, which would make your foundation footer about 7' below grade. Are you saying the creek bed near your house is above your basement floor elevation-wise?

Is this seepage a recent development or something that's always happened?

Anyways, there should be a drain pipe that runs all the way around your foundation at the footer level. From the floor drain and gutter drains you describe, I would guess they tie into that foundation drain pipe. But, snaking from the floor drain to the creek doesn't prove that you have a complete foundation drain installed.

If you have one, it functions exactly like a french drain. It collects water below your basement floor level (which is why it is installed next to the footer, usually on the outside of the wall) and reduces the static water pressure by giving the water an easy way to run away rather than seep into your basement.

One possiblity is your foundation drain pipe, if present, is clogged in an area not inspected by the video snake. Certainly after a good rain, you should be able to see water running out of the pipe into the creek. If you don't, it ain't working or isn't there. In Spring time or wet periods, it could/should run continuosly for days at a time.

A pic of your house wall outside where the seepage happens and the slope behind it and the creek would help if you can post one.

Dave.

 

[TeamNH]

How many coarse down is the water coming in?
After a big rain or snow melt is there standing water on the ground near the house?

If there is no standing water... and the water is leaking in many coarse below grade then I would think you'd at least have to get down to that level in your drain for you to start collecting the water and moving it. Make sense?

 

[rswyan]

Water leaks where the block meets the slab, on the uphill side of the foundation of course. With one heavy rain it'll get damp in the corner.

Does any portion of the land surrounding your home slope downwards towards the house ?

IOW, do you potentially have surface runoff (as well as ground water perhaps) flowing towards the foundation ?

There's a very steep slope behind the house where the leaks are.

Sloping towards the house ? :shocked:

If the above is the case (with a small pond forming every time it rains .... possibly covered up by the deck so you can't visually observe it) you need to do something to divert the water away from the house before it ever gets there.

This could be a diversion ditch which diverts the flow .... or it could be hard (solid) drainpipe with inlets placed at ground level at strategic points ....

In any event, if you ultimately have to install a french drain somewhere near the foundation to remove subsurface/ground water, any plumbing you do for surface water drainage near the house, should not be tied into the french drain - unless it is tied in far downstream/downgrade from the foundation - thereby avoiding the possibility of actually making the problem worse, by giving the surface water an easy path to get underground near your foundation.

Ideally, all surface drainage (including gutters and downspouts) would use hard (non-perforated) pipe - at least anywhere near/upslope of your foundation ....

French drains use perforated pipe of course ... and while both types of drainage can occupy the same trench (perf pipe at the bottom, hard line higher), they should not use the same type of pipe, nor should they be connected to one another (for obvious reasons)

Got any pictures ?