| Posted in General Discussion on
Does anyone know the current thinking concerning how to orient SDR-35 foundation perimeter drain pipe? I’ve asked various professionals and they seem to be split on whether to orient the half-inch drainage holes up (at 10 o’clock and 2 o’clock) or down (at 8 o’clock and 4 o’clock). And to confuse me even more, one guy says the company he works for orients them at 1 o’clock and 3 o’clock. They all seem to have good reasons for doing so, which leaves me to believe that it doesn’t really matter which way the pipe is laid. Anyone have any strong opinions on this?
Thanks in advance for the feedback.
Ethos | |#1
The relationship between the bottom of the footer and the bed of the pipe is where your answer lies.
Think about the function of the drain: it's there to de-water everything above it. If the perforated pipe is laid adjacent to the the top of the footer then it would be best to install the pipe with holes at 5 and 7. The optimal install would have the pipe laid so as to de-water everything down to and slightly below the low point of the footer.
But, there are other factors that will affect how the drain performs, and the detailing of the entire backfill outside the wall, including a compacted base and filter sock for the pipe, washed rock above and a pitched, impermeable cap at finish grade and gutters and leaders abovewill all affect the performance of the install more than the minutiae of where to put the holes.
The question really is: how much water has to be dealt with and whatwill bethe result of an imperfectly functioning drain? If it means a wet basement or something else critical, the entire install needs to be looked at very carefully.
Barncat5 | |#2See Also2 inch flexible drain pipe
So what you are saying is that eveything else being equal, it really doesn't matter which way the pipe is laid? Which is something that I've sort of suspected, but I've been told that the drain holes tend to clog up with silt much easier if the pipe is laid with the holes down, as opposed to up. I have no doubt that up or down, water should be able to flow adequately in the direction of the general pitch, its the silting issue that I'm wondering about. Any ideas about that? Thanks.
xMikeSmith | |#3
barn.. the pipe will clog with silt no matter which way the holes are set..
they are designed to be set at 5 & 7.. the pipe should have some pitch ..
now that filter fabric is readily available, we always sleeve out pipe with filter fabric before we set it..
we used to use red resin paper for the same thing ... some used newspaper.. but filter fabric is far superior.. keep the silt out and the holes at 5 & 7... for water below..
at 11 & 1 for water draining from aboveMike Smith Rhode Island : Design / Build / Repair / Restore
xMikeSmith | |#4
here's a pic of the pipe sleeved with filter fabric before we install itMike Smith Rhode Island : Design / Build / Repair / Restore
Barncat5 | |#8
Thanks for the picture, Mike. Do you also then use filter fabric to cover the sleeved pipe/washed stone installation? If so, it sounds like a very silt-impermiable system.
Mongo | |#9
Definitely holes down...you want to drain the water, not float the pipe.
Sleeve the pipe and cover thestone with fabric.
Investment is minimal and the payoff is big. Price out the cost differential of using the fabric up front vs digging out and R&Ring a silt-clogged drain field down the road.
woodchuckc | |#10
Don't mean to hijack the discussion, but would anyone care to post a manufacturer or even better yet, a vendor for the filter sleeving? I'm getting ready to put the foundation in for a 26x60' garage / workshop and need to lay in foundation drainage on the uphill side, but haven't found any local building supply houses that carry it or even know where to get it (very rural middle / west TN).
xMikeSmith | |#11
our filter fabric comes in 6' x 250' rolls... the material lookls like black felt ( like dressmaker's felt ).. we cut strips and make our own sleeves.. i use one of those stiching staplers like they use for insulating hot water tanksMike Smith Rhode Island : Design / Build / Repair / Restore
dIrishInMe | |#5
Holes down. Attended a basement waterproofing seminar and that is what the guy said/literature showed, and I have read several articles to that effect, so that is the way I do it. Otherwise the pipe gets clogged with sediment.
We have heavy clay in our area, and I have found from personal experience that that sleeving they sell for drain tile will clog in the clay so I don't use it. Rather, cover the pipe with 3/4" washed stone (gravel) and then cover that with septic paper, which is both economical and effective.
Be sure your drain tails daylight (an above ground, downhill,outlet for the drain system), and keep a close eye on the drain tails during later phases of construction so they can be repaired if they get crushed - which they often do.
Piffin | |#6
I've got to admit that I'm surprised, not only at the question but at the range of responses you've had. With well over thirty years in building, I have never heard of anyone setting it any other way than with the holes down at 5&7.
If you face them up the pipe will silt up to the holes, at least.
With the holes facing down, it will not silt in any higher than the holes themselves, leaving a lazy D chamber for water to flow through. It is the path that you are looking for so you want to preserve it. With holes down, if theyu get silt up that high, water can still find it's way into the drainage chamber due to hydrostatic pressure and it can then find it's way downhill.
It's all about giving the water someplace to go, other than in your cellar.
I suppose that in plenty of washed gravel with a sleeve, it is not likely to make much difference, but it is designed to be installed holes down.
Excellence is its own reward!
rjw | |#7
I say down, 5 & 7, because you want to darin as much water as possible. If you have them up you're not draijing hundreds of gallons of water which will then be trying to get into the subgrade spaces.
And the sump pump should activate before the water level reaches the bottom of the tile for the same reason._______________________
10 .... I have laid the foundation like an expert builder. Now others are building on it. But whoever is building on this foundation must be very careful.
11 For no one can lay any other foundation than the one we already have--Jesus Christ.
1 Corinthians 3:10-11
tkiser | |#12
Holes Down. we use a product called Form-A-Drain. http://www.formadrain.com/I also do something people will disagree with I run 4" drain tile holes at 5 & 7 that are attached to the gutters that run on top of the footers and 1" washed gravel over the tile. My idea is that the water from the roof keeps the drains cleaned out and the tile will not settle.
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