I keep getting different responses from so many people so I thought I’d ask here.
I’m backfilling about 250 L.F of foundation that was just poured. About 3′ deep.
The ground is clay. Its horrible so, I figured I’d have a concrete truck come and pour me about a foot of gravel (a nice tip from my concrete guy). Lay drainage pipe in it to a drywell.
I heard they sell drainage pipe with a sleeve over it to keep the soil out vs using cloth ontop of the gravel
What do you think the best method is?
6″ of gravel, pipe, 6 more inches of gravel on top and cloth, than use bankrun for the remainder?
Thanks
andy
The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
Replies
Andy,
I do a lot of subsurface drainage (sitework contractor). don't use the sleeved corrugated perf - it clogs easily with fines. What has worked well in my experience is 4" corr perf laid on the excavated clay, backfill with pea fill (no compaction needed / no settlement) or other agg (will settle). Any fines that get in the pipe will settle between the ribs and give nice flow characteristics to the pipe. End caps needed - SSD will carry pea fill in a hurry. Also it's easy to overwhelm a french drain, can you daylight it in a rear yard swale?
remodeler
SSD ???????
How much pea gravel do you think is sufficient? One foot over the 4" perf pipe than 2' of bankrun?
Makes sense having the pipe end in light....have to see if thats possible here.
Also, do you think its necessary to run the pipe around a garage (slab) ?
And as far as pitching the perf pipe....any suggestuions?
Thanks
andy
The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
Edited 9/11/2003 3:48:22 PM ET by Andy Clifford(Andybuildz)
forget about the bankrun. fill to grade with sand and be done with it.
For pipe slope, I'd use a minimum of 1%, more always being preferable especially with coil pipe due to it's tendency to develop undulations. If you really want a cadillac product, look into using ADS N-12 pipe. It's corrugated HDPE (like coil pipe) but has a smooth interior for better conveyance and is much stiffer than coil pipe. I've heard of situations where coil pipe was backfilled then later excavated only to find it had collapsed. N-12 is what you'll see often for culvert pipes beneath roads. It is available in perforated form. You'd probably be OK with standard perforated coil pipe but the N-12 is like $0.50/ft versus $0.25/ft for coil pipe, so the material cost is miniscule.
I didn't know that the ADS N-12 type pipe came in 4". Thanks for the info. You are right, that coiled stuff is pretty flimzy, and for example, it's always a loosing battle to keep the drain tails from getting run over and crushed by the grader. I stake and flag the tails, talk to the grader, and then 1/2 the time he moves the stake/flags, runs over the pipes, and then puts the stake back... :( Matt
stone....Its suppose to rain the next few days so I won't be getting to my trench...not to mention the mud after a rain in clay is incredably disgusting here.
I'm definatly going with a more ridgid pipe like the N-12. Thanks!
I have about 250 LF to lay in the trenches.
I figure it'd be easier to pitch than the coil stuff besides.
Still have to figure if I have to use a drywell rather than letting the pipe end see light......I may have a problem with the town via the light route.
Thanks
andy The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
The whole point of foundation drainage is to have the water drain somewhere - did you do a perc test to find out if the drywell would be any more efficient at draining away the water than the native soil conditions, or you'll just be supplying an eventual source of water ?
Phill Giles
The Unionville Woodwright
Unionville, Ontario
Phill
Perc test? Well put it this way...where the ground was dug in the center for piers....it rained and the water stayed in those holes for about a week or more...lol.
I know when we dug down doing the foundation trenches there was sand after about 15' down so if I have to use a drywell I'll be sure to go down that deep.
Gonna try and see if I can vent the pipe to daylight first though.
Thanks
andy The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
You said: "I heard they sell drainage pipe with a sleeve over it to keep the soil out vs using cloth ontop of the gravel"
I used the pre-sleeved corrugated pipe for a foundation, and did not backfill the outside of the house for a few months. (clay soil) The Foundation could not drain, other than through the draintile tail that was exited to daylight. The drain-tail trench was backfilled. After about a month the "sock" around the pipe clogged and the foundation was not draining; there was standing water in the area to be backfilled. I cut the "sock" off the pipe so it could drain, and later added washed gravel, septic paper more gravel and native soil. Draw your own conclusion.
BTW - exit your drain system daylight if at all possible. A drywell isn't dry when it rains... and that's when you need it.
Matt
I was kinda thinking the same thing about cloth or a sleeve but thanks for the first hand information.
Andy The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
I'd stay away from sand for backfill. It will migrate into the drain tile and once it gets mixed with silt, etc, will clog the pipe. Just my opinion, based on things I've read.
Matt
I agree with avoiding sock pipe. One modification to the peastone backfill- lay down non-woven geotextile first, lay the pipe, backfill with peastone (about 1 foot over the top of the pipe is more than adequate), and flop the geotextile back over everything to close it all up. This is commonly called a burrito.
FHB had an article a few months ago called "Keeping basements dry" or something to that effect. The author suggested using a layer of sand directly above the burrito then general fill above that. I guess the rationale behind the use of sand was to filter out any fines from the general fill that could potentially clog the burrito. Makes sense to me.
One other thought- don't carry any real permeable backfill (i.e., sand, gravel, etc.) up to the ground surface. The last thing you want is to encourage what would otherwise be surface runoff to want to infiltrate down. You really are just looking to avoid water buildup outside the wall. The first line of defense for this is tighter soils at the ground surface to turn the rain into runoff and then a good pitch away from the wall.
If the foundation is 3' deep, are we to assume you're in a freeze/thaw area? If so you still may have trouble with your seep line freezing.
We're in freeze/thaw territory and do as follows: 2" to 4" of 3/4" stone from the footing out 10" to 12". Use 3/4" stone, not road stone with fines. It too is self compacting (trench backfill). Lay the plastic drain tile, returning each end to a T and a sleeve that goes back through the footing into a drain sump inside the foundation. Put a sump pump in the sump, problem solved. Cover the drain tile with 2' of stone. We also backfill all the inside of the foundation excavation and floor with trench backfill and the garage inside foundation and floor.
Question, Andy, by chance, are you going to install some "cleanouts"?? I would. I also use, either 3" or 4" perforated pipe in 10' sticks, I'am not a fan of the Coiled drain pipe. Be safe out there , and don't forget to have some fun. Jim J
Yep.....hopefully 2 clean outs. Building inspector is suppose to be here today so I guess he'll let me know "exactly" what he expects. The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
In the gardeners world they use root blankets under the tiles in the garden. Blanket > gravel > sand fill > tiles. Thats also what we use here in Holland.
Willem the Hollander,
Gardening 18ft below sealevel
Willem
I think I'm going to go with the boretto idea.
Fabric on the clay soil folded up then the pvc perferated pipe, a foot of pea gravel,fold the fabric over that than a foot of bank run and top it all of with my clay soil pitched away from the house.
Probably have to dig for a drywell as well down at the sand level.
thanks and be well
andy
PS.My wife is Dutch The way we regard death is critical to the way we experiance life.
When your fear of death changes, the way you live your life changes.
http://CLIFFORDRENOVATIONS.COM
Well were's she from? There are many "Dutchies" around here.Willem the Hollander,
Gardening 18ft below sealevel
Everyone talks about the sock clogging, but no one is talking about filter fabric. I lay a 3' wide strip of filter fabric in the trench, with one edge wrapping up onto the footing. Then a thin layer of washed crushed rock, just enough to keep the pipe off the ground. Then the pipe, with sock. Then 4-6" more washed rock. Then another layer of filter fabric, edges rolled together with the first piece of it. Then enough crushed rock to cover that. Then backfill. And definitely run it out to daylight if grade permits.
Formerly BEMW at The High Desert Group LLC
Bruce,
Doing my piping today (Sunday...ugh).
I'm using ridgid PVC perforated. It'll be laying on clay so I don't worry about whats going to wash in the holes too much from under the pipe.
I have 2 100'X3' rolls of landscape fabric to lay over the pipe folded up two sides of the walls.
Monday or Tuesday the 20 yds of pea gravel comes....I'll pour that over the pipe and fabric and wrap the fabric around top of the gravel.
Another 21 yds of bankrun ontop of the gravel and then top it off with the clay pitched away from my house.
I have about 200' of run to do.
thanks
andyTrue compassion arises out of the plane of consciousness where I "am" you.
http://CLIFFORDRENOVATIONS.COM
Generally you need stone under the pipe, I do 4" under and 8" to bury the pipe after it is leveled.
One small detail, "pea gravel"? You should have 1 1/2" stone, either crushed or tailings. Pea stone around here is 3/8", and gravel is mixed stone and dirt.
Backfilling with gravel is fine, and capping with existing clay soil makes a lot of sense, but be careful what sort of gravel you order. Anything from sand fill to 3" minus gravel will be fine, just don't order anything larger.
QT
I shouldnt have said pea gravel.Wasn't what I meant...I'm using what they call around here fill gravel which is what you described.
I'll be pitching the pipe with large rocks under it so I know several inches of the gravel will be getting under it.
I'll be down in the ditch as my excavation guys feed it to me.
Me down there with a shovel spreading it and keeping the landscape fabric taught... so I'll be sure to get plenty of gravel under the pipe to keep it stable and properly drainable.
PS....I'll stay in touch! Might even ask for your phone number if you don't mind.
BE well
andyTrue compassion arises out of the plane of consciousness where I "am" you.
http://CLIFFORDRENOVATIONS.COM
I assumed you meant pea stone to surround the pipe, many people call stone gravel and it gets confusing. The problem is pea stone is too small to use with schedule 15. I use 3/4" - 1 1/2" stone, usually 1 1/2" tailings because they are available and cheaper, and I'd rather not have to spread crushed stone if I can help it. Depends where you're at. Another advantage is you toss the first layer and set your pipe solid, then cover it and get back in and rough grade it.
You don't need anymore than a hint of pitch, this isn't a waste pipe, and the stone bed itself acts as a drain. The first 4" is to give you something to set your pipe in and get your "level", and also to give any fines that filter thru a harmless place to end up. The additional 8" covers the pipe and is more than enough for a drain bed.
The fabric on top and over the outside is fine, maybe lap up the wall, but this isn't rocket science. the fines come down and in, and whatever you use, (I use rosin paper), will soon form a virtual impermeable barrier from the settlement of the fines. Why fabric under and towards the house? Think about it. Capping the backfill with tight soil prevents the downward migration of surface water, but make sure you exagerate the finish slope to allow for the inevitable settling and to provide a positive slope away from the house.
Ps. send me an email, I re-comped and everything on this one is new, or very old.
QT
as was said in this thread before somewhere, that the "Borrito" package helps keep the fines outta the gravel.
Personally and gut feeling is..which is why I used ridged pipe rather than corragated pipe is that the fines that do get through will wash away into the sandy drywell.......
Most of the drainage from the house part vs the 30x30 shop part will/is set on sand and goes to light.
PS....I'll email you.
BE well
andyTrue compassion arises out of the plane of consciousness where I "am" you.
http://CLIFFORDRENOVATIONS.COM
I believe the article in FHB said much the same thing you said. The pipe does not need to be pitched or sloped. The purpose of the drain is really just a "path of least resistance".
In Andy's case if his clay soil is as dense as the stuff I have around here, there won't be a lot of fines. I have to work at breaking the stuff up in order to not backfill with hugh clay clumps. The rock under the pipe would be more to catch the fines that wash under the fabric.
I just poured my first footing with Form-A Drain. Since it is the form and drain all in one, it was set dead level. So far I have about 8" of crushed stone 3/4 to 1 1/2" up agianst it, and will add the remainder and filter cloth after the wall is poured. I'll exit to daylight on the downhill side of the walkout.
Suppose to rain tomorrow, so I'll let you all know how the dead level drain works.
Dave
Yep, and gravel backfill will minimize hydropressure against the wall. It works.
For sure get back with details on your drain.
Around here the soils can be anything, so the drainage is different for every house.
The boritto is nonsense, and counterproductive to service, production and economics. It's a circle jerk, if you ask me.
What do I know, I have a full basement under the water table, and you are doing slabs.
I've got to disagree on your opinion of the burrito concept. First off, it's practically a given in any type of subsurface drainage system design (I know that this does not necessarily mean it has to be used). The geotextile is there to prevent the loss of soil around the crushed stone. Anytime two soils having radically different grain size distributions are placed next to each other, there is a potential for intermingling of the soil particles. The geotextile acts as a transition to contain the finer soil particles of the surrounding material. Without this, you'll probably either end of clogging the drainage stone or greatly reducing it's ability to transmit water to the pipe and defeat the whole purpose of the subsurface drain. You could also end up with problems such as sinkholes due to loss of fines. Bad idea to skip geotextile and contrary to just about every reference out there, including a recent article in FHB.
On a slightly different angle, but certainly fits in this thread:
I've got an excavation that includes a standard hieght basement with crawl space footing walls adjoining. The drainage tile (in my case corrugated with sock) runs around the footing wall and around the basement wall footings.
Plan similar backfilling schemes as already represented, and am digging in mostly clay with and then into broken limestone at about 5' from grade.
Where the excavation steps down from footing wall depth to basement depth, the excavator just left the tile hangingover the edge of the step down...not coupled with the basement tile, which is set within the pea gravel footing (wood basement). Says water will find its own way down to the basement tile, which then runs to daylight (sloping site)
Should I go to the extra work of coupling the tiles, or is the excavator correct?
By the way, in agreement with others on this thread, my guy ran the tile dead level.
I think I understand. You've got two drain systems- one higher than the other and you're excavation guys wants to let the upper system just stop, thinking that the water will percolate down and reach the lower system. In all likelihood, the water from the upper system probably would eventually enter the lower system but I wouldn't recommend this appoach.
First off, I'd be concerned that all the water from the upper system would overload the lower system because you've got basically a pipe discharging its flow at one location. Second, I'd be concerned about erosion of the soil at the outlet of the upper system. Third (and probably most importantly), the upper system isn't going to function properly because it no longer is free-draining. Although it can collect water, it has to wait until the soil at the open end of the pipe can absorb it. May as well not even install the upper system in that case.
So, I'd go through the trouble of tieing the systems together or just transition the upper system to solid wall pipe (not perforated) and run it till you can daylight it.
Regarding pipe slope, I'd try to pitch the pipes. I know that if it builds up with water, it will eventually flow but a slope is always better. I'd shoot for a minimum of 0.5%.
You got it....that's exactly what I'm concerned about. Well, all I really have to do is dig pea rock, and then put a tee in.
Thanks alot for your considered response.
The wet test of the Form-A-Drain was a qualified success. I say qualified b/c there is no fill over the exposed footin, only the crushed stone.
I checked the open ends of the forms after we got about 1 to 1 1/2" of rain the other day. Forms are set dead level and there was water both inside and running out of the forms. Not much pressure to force the water into the drains at this point, since all sides of the hole are open and can easily drain , but this is fair indication that the system will work.
Dave
Very cool, thanks for following up.
My basement slab is under the seasonal high water table, and I did a few things above a buritto. M/l a foot of stone thruout w/ weepholes in the footings, drainbed covered with a barrier top and outside, drain to daylight, sump for backup, sandfill backfill w/ silt cap surface pitched to runoff. It works.
But the details are crazy, every soil is different, every house site is different.
I built my inlaws house 12 years ago and put in 10" of crushed stone beneath the slab. Perimeter drains to daylight, but no interior drain tiles or sump. Poured the slab b/f framing the walkout and formed out where the loly colums set. A wet winter caught me before I could get the grade pitched right. I ended up with enough water under the basemnet slab that the loly colum holes were the relief ports. I dug out the rear foundation wall, drilled weep holes and built a French drain to daylight. It still took a week for all that water to clear from under the slab. Corrected the surface grade issue in the spring and the french drains have been dry since then, but they are still there if needed.
That is one of the reasons I am using Form-A-Drain for my footing forms. Gives me exterior and interior perimeter drain tiles in situi with the forms.
Dave
FWIW I ended up using pretty large gravel and I did pitch the pipe towards a drywell of two 4x4 rings on top of really fine sand.
I poured the gravel under and over the pipe and then laid my fabic over the gravel and poured my bankrun over that, and then the extremely dense clay soil over that, pitched away from the house......One section of the house I was able to run the pipe to light....looks good to me.
No basements...just crawl spaces and slabs for the garage/shop and porches.
Gee, I'm gonna start framing soon. Who'd a thought?? Isn't that what comes next...lol
Be well
andyTrue compassion arises out of the plane of consciousness where I "am" you.
http://CLIFFORDRENOVATIONS.COM
No, No, No!
Foundation party, then framing, then framing party, the roofing, then roofing party.....
Celebrate each small victory and success in life!
(you may want to do your underground plumbing rough in b/f you get all those floor joist in the way,... another party)
Dave
Dave,
I've got a plumber I like coming tomorrow to give me a low down..hope he doesn't get all bent outta shape if I ask him what he thinks...lol
I think the parties will be a case of Corona's untill I'm dried in. Then it'll be boiler makers...lol
Be well
andyWe're being trained through our incarnations-trained to seek love, trained to seek light,trained to see the grace in suffering
http://CLIFFORDRENOVATIONS.COM
ARGH!
"I poured the gravel under and over the pipe"
It's stone, man, you got stoned! Right?
Gravel is dirt.
Lol, glad to see you getting close to wood. How's your buddy the building inspector doing, figure another visit for the co? Well, you ought to let him see the rough. ;-)
QT
The BI really likes me and what I've done so far...apparently no one round here ever uses ridgid pipe.
I passed the inspection with flying colors and I'm waiting for my delivary of plate materil, TJI floor joists and A whole buncha sheets of Advantech this morning.
Only snag is, my concrete guy put me off till Friday if I'm lucky to pour the scratch coat in the main living area so I wont be able to get the TJI's in till next week.....ugh. Hope he shows up......sure is startin' to get cold. I imagine up by you its even colder....a-duh. Cold doesn't bother me.its the snow I have issues with unless I'm skiing.
I don't have many concerns about framing the walls...its the roofs that will be the trick on this ol' house.
Hope all is well with you guys up above me.
PS...spose I keep calling it gravel cause thats what the excavation guys call it...the sand they call bankrun.
aWe're being trained through our incarnations-trained to seek love, trained to seek light,trained to see the grace in suffering
http://CLIFFORDRENOVATIONS.COM
Actually, the weather is just perfect, but I have a lil addition that won't be ready for wood for a month. Hmm, the last two years we had snow in October...
About bi's, the job is down where the bi said I would never pull a permit again. I hope he has been working on his attitude, because mine hasn't gotten any better. <putting on my most innocent look>
QT
I so lucked out with my BI...I'm hoping its karma....He even said he thought about buying this crib but it was too much of a challange for him...almost asked if he could help me on weekends but he said it would be a conflict of interests...
And yer right..this weather couldnt be any better as long as it doesn't rain....the entire excavated site is clay..ever walk around in that after a rain....and it doesnt dry out for over a week? Whewwwwwwww Muck city and twenty pound work boots....you gotta see the inside of the house...my wife gave up on vaccuming....What am I spose to do......unlace my boots and take em' off every time I walk in????? I just keep a broom in every room.
Be well
andyWe're being trained through our incarnations-trained to seek love, trained to seek light,trained to see the grace in suffering
http://CLIFFORDRENOVATIONS.COM
"What am I spose to do"
Lose the clunky boots, spread hay all over the place and chant "I'm sorry honey, I'm sorry honey..."
yeh.....someone round here told me bout that hay idea..reckon I may just do it now that you bring it up again.
The wifes just happy I put planks and plywood over the hole in front of the front door where the footings for the front porch'll be,,,,,,imagine when I start framing ; )
Wheres that damn truck already......
aWe're being trained through our incarnations-trained to seek love, trained to seek light,trained to see the grace in suffering
http://CLIFFORDRENOVATIONS.COM
Wow, it took 3 days for someone to disagree with me? You guys are slipping.
I went into more detail in message #24, but I agree with most of what you say. You have to protect the drainbed from the top and outside. Use geo if you want, I mentioned rosin paper and have seen all sorts of barriers used. Whatever you use will catch the filtered fines and form a sort of mini-hardpan in sort order.
The barrito concept is a waste to me, there is no reason to filter under or towards the house, and it is a pita to install. I wish I could say it would cause no harm, but in many cases the restrictions it imposes on obtaining the ideal drainbed is evident, not to mention the costs.
You use what you want, be good...
I see what you're saying- up against the wall there's no source of fines so why bother having textile there. Also, I guess the PITA issue is because the loose edges of the textile want to fall back into the trench while you're backfilling.
I like the burrito idea because there is basically only one point for fines to get into the stone and that's where the textile wraps over onto itself. Also, the burrito maintains the separation of the stone and surrounding soil at all locations (i.e., bottom, outer side, and top of the trench), whereas simply putting a textile down over the top of the stone only gives you a barrier across the top. While the textile beneath the stone may not seem important initially, keep in mind that if the drain tile is below the water table, the drain could end up seeing an upward flow of groundwater. The underlying geotextile also serves to prevent the stone from mushing (my technical term) into the underlying soil. In summary, I doubt the backfilling PITA issue would offset the PITA of replacing a clogged perimeter drain.
Also, I'll try to be more timely in attacking your ideas... (kidding).
Edited 9/24/2003 4:02:09 PM ET by stonebm