Footing Drains

jjtt

I built a house last year for a client that was in a wet area. We excavating the site (mostly clay), brought in 40 yds of scalpings, a sand and pea gravel mix, and poured the foundation. Footing drains and down spout drains were installed to code but we are still getting some water in a corner of the crawl space. I installed 4" perf. pipe around the perimeter. Bottom of pipe is level with bottom of footing all around the home. Backfilled w/drain rock and covered with filter fabric and native soil, drains to ditch. H.O. says footing drain should have 1-2% slope and my responsibility for any water in his crawlspace. Water in C.S. is only evident during hard rains and seems to disipate afterwards. Not good enough for H.O.

Any suggestions or comments?

Coastal

Its code in my area to put perimeter drains on a slope, and I would hope it is everywhere. You might have to put a sump in and pump it out to the ditch. Whats the slope like to the ditch from the level of the perf pipe?

jmic

jjtt,
Did you run footing pipes and leader drains into same system or are the leader drains going into their own solid pipe system. What kind of pipe did you use for footing drains and leaders system ( please don't say that black corragated _rap that comes in coils ). If they are seperate systems do they each run to daylight or did you connect them to one runoff? Does any water come out of the runoff during moderate to heavy rains? Maybe you have a crushed outlet pipe impeading the flow out. A little more info. would help. Good - luck,
Joe

K2

Where is C.S.?? Colorado Springs?? Yes the drain should have slope. One of the problems I found was that the excavation holes are not perfectly level and if they are pitched 1 in. in the wrong direction that can create a problem. Also if you dug a hole in clay and dumped sand and gravel in, that would be like dumping sand and gravel in the bottom of a swimming pool. No place for the water to go. I would have put a drain at the bottom of the excavation also. If the excavation was reasonably level you could still probably drain it fairly easily. If you had no ground water in the soils report and all you are dealing with is surface water that should be able to be dealt with. I personally would be leaning toward draining the bottom of the excavation. I did that one time and it was not too expensive and it worked. RT

Edited: One more thought. Where the water is collecting in the crawler is probably the lowest point of the drain. If you can daylight from there that would probably solve your problem. <P>

Seems like sand and gravel would be the wrong material to be putting over clay in an excavation. We always used our red roadbase which would shed water.

DecksEtc

I'm guessing he meant "C.S." to stand for "Crawl Space"???

Tom R

I thought it was, - - never mind!!

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K2

Oh yea. Crawlspace.. Forget what i said.

toolaholic

on site while it's done! slide country! sdr 35 pipe 3/4" crushed gravel,
filter fabric . compaction in 6" lifts. then the surface is swalled to drain
water is drained with a defuser 12" below found on hillslides. tite line for down leaders [NEVER MIX with footer drains] all pipes have surface clean outs. it.s expensive and good.

some times in marin co.when you come home,

your house comes down the hill to greet you tool

chrisherk

everything ive done to date has had foundation drains, but i bid a job recently and the septic plans says i dont need them. The soil is all sand and the high water table is actually below the footings. I did figure them in my price, just in case, but i dont think i should put them in. any body ever run into this?
chris

jmic

Chris,
In rear circumstances sometimes in order to keep seperation distances between septic system and footing drains (usually a short section ) an engineer will have you use tight pipe to make the connection to the rest of the footing drain loop. I'de never consider doing a full basement without or even crawlspace area for that matter without foundation coating and drains. Water tables can change over the years for one reason or another. It's just cheap insurance compared to dealing with water problems down the road.
Joe

ApgarNJ

I usually have the mason install my foundation drains using sch35 s&d perferated pipe. The mason just poured the footings for a new addition we are about to start framing and i decided that I am going to do the drain pipe on this job. My excavator was there supplying me with stone to use while installing the pipe and said that the holes should face down,
and I thought they should face up, and that the top of the pipe should be a few inches below the top of the footing, so if any water comes down from above or even from ground water, it will pour into the holes and run out the pipe. he said he's always seen the holes faced down in a few inches of stone, then cover the pipe with clean stone and filter fabric, and back fill.
what do you guys do, holes up or holes down? just doesn't seem right to me to put the holes down, but he says it will catch the water faster as it comes up from the ground, but I think that it just makes it so the water has no place to run in the pipe. i made sure there was pitch to the drywell we have to put in later on.

Tom R

Definitely not my expertise, - - but until you get a 'real' answer, - - I do believe 'holes down' is the much preferred method. Once the water comes up and into the pipe it will run just fine as it will seek it's own level.

kid creole

what do you guys do, holes up or holes down? just doesn't seem right to me to put the holes down, but he says it will catch the water faster as it comes up from the ground, but I think that it just makes it so the water has no place to run in the pipe. i made sure there was pitch to the drywell we have to put in later on.[/QUOTE]

according to the research i'm doing for my g.c. lic. holes should be up on a slight angle away from house.does'nt make to much sense for the hole to be down as the pipe and gravity won't work together to drain.

jmic

I'll usually run one set down and the other set of holes towards the footing, right or wrong as long as you use plenty of clean stone and cover good with fabric the water will find it's way into the pipe and on out to where it's piped.

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Joe

ApgarNJ

yeah, i slightly angled the pipe so that the holes were not just dead center on top. figured the water could get in a little easier. i have 3 inches of so under the pipe and the whole bottom around the footing is clean stone. we'll add a little bit more over top of the pipe once the block work is done.
thanks for the info guys.

jmic

We usually mound 6" - 8" of stone over the pipe.

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Joe

denick

This is the correct way to construct a footing drain. With the holes in the pipe on the bottom. The dark outline is fabric on bottom, outside and top. The stone goes up and over the footing at least 2". The pipe is set level with 2" of stone below it.

Set this way the water in the drain starts to run through the pipe when there is 2" of water in the stone which should be 12" below the floor height if a 4" floor is poured on top of the footing height.

If you turn the pipe with the holes up the water has to build up to 5" of water in the drain before it starts to enter the pipe. If you raise the pipe so that it is near the top of the footing there can be 9" to 10" of water in the drain and be at the bottom of the floor height before it enters the pipe.

In any drain built with stone and pipe the water only enters the pipe when there is an overwhelming amount of water moving through the ground.

Water coming down from above will always find its way to the bottom of the drain through the stone before it enters the pipe.

I can't seem to get the picture into a format I can upload as a picture.

Attached Files

foot.doc (23.0 KB, 317 views)

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Nick

"Every day I remind myself that my inner and outer life are based on the labors of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am still receiving" Albert Einstein

tgeb

I agree with Nick 100%! Holes at the bottom.

Here we use the flexible corrugated pipe with perforations around the entire pipe. Only around the foundation and bedded in stone, never for the outfall or daylights, PVC for that.

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Tom

www.gebcon.com

jmic

Can't say that I have much faith in that choice of pipe.

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Joe

ApgarNJ

I don't use that black corrugated stuff either, it's all junk. my excavator has to replace that stuff all the time on various jobs that he gets calls for, not really for footings but for other drains.
well. i guess next time i'll put the holes down. the water will run in the pipe and out the end, so it'll be fine.
the whole job is on a hill too, so drainage is really good anyways.