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Old 03-12-2012, 01:24 PM   #1
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French drain pitch


How much should piping for a French drain be pitched toward sump pump?

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Old 03-12-2012, 01:46 PM   #2
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French drain pitch


No pitch should be required at all.

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Old 03-12-2012, 01:47 PM   #3
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French drain pitch


Quote:
Originally Posted by TarheelTerp
No pitch should be required at all.
If its not pitched, how will water drain to pump?
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Old 03-12-2012, 02:57 PM   #4
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French drain pitch


For some reason, water is very smart and always seeks to lowest elevation. Using the cheap, slotted, corrugated pipe can cause big problems, sediment accumulation and bellies that cause even more problems.

French drains at the bottoms of footings of a foundation are always laid horizontally with PVC (or should be).

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Old 03-12-2012, 03:13 PM   #5
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French drain pitch


For some reason this particular question seems to come up a lot. There is an urban myth that the water flows toward the pump because the pipe is pitched towards the pump. As previous posters have pointed out, this is NOT TRUE. The water flows towards the pump because the water level in the pump pit is lower than the water level in the pipe. This occurs because the pump drains the water out of the pit, lowering the water level. So I concur with concretmasonry, I always set the pitch at zero in the pipe. If the pipe does pitch towards the sump, that is OK, the problem is that the basement floor is typically flat, and with any pitch at all the pipes can be too high in the corners. Remember, you want your pipes to be lower than the basement floor, usually by a foot or so, because the objective is to keep your basement dry.
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Old 03-12-2012, 05:12 PM   #6
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French drain pitch


1/4 per foot! that is Uniform Plumbing code.
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Old 03-12-2012, 05:55 PM   #7
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French drain pitch


I don't think that a french drain could be controlled by a plumbing code since it is outside the habitable building volume and usually discharges to the exterior especially with a gravity discharge. Certainly the traditional (centuries old) systems for water control were not under government control, but they were built by the Romans and lasted centuries.

The golf course I play has a myriad of french drains that are working daily (without plastic pipes) after 80 years.

I don't think there is anyone on the committee that writes that fictitious part of the code that is even qualified to determine the properties of the aggregare that is used to increase the moisture control envelope.

The only way that would fall under a real code would be once the water was collected and until it was discharged mechanically. Certainly a plumber is not qualified outside those parameters.

I sat on a code committee when they chased a fellow structural engineer out of the meeting because it could not possibly be a structural item and an exclusive civil/soil situation and a structural engineer is not necessarily qualified for.

Dick

Last edited by concretemasonry; 03-12-2012 at 08:34 PM.
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Old 03-12-2012, 10:29 PM   #8
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French drain pitch


Well Here is my back ground I am retired Union Journeyman Plumber It has pipe it goes to a sump and it goes to a pump. It falls under the UPC and it is a 1/4 inch per foot. How hard is that to understand. It seams like that when some one points out something that they have knowledge on you seem to come back very insulting. I am not even going to second guess you on mason work or cement work why It is work I don't do. I gave the man the correct information. and BTW yes the Aggregate does need to be specific sized at least 5/8th min. That way the drain does not fail in a few short years.
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Old 03-12-2012, 10:33 PM   #9
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French drain pitch


I don't pretend to know the UPC. I have designed a dozen or so perimeter drains for commercial and industrial buildings, and they were all designed using level pipes. They all work fine. The point of the pitch on sanitary pipes is, so far as I understand, to make sure the pipe drains completely, and to maintain a minimum flow velocity to scour the pipe. Neither applies to groundwater control systems, since the water is clean, and the pipes are not going to clog up regardless of flow rate. But if groundwater control systems come under the UPC, I would be very interested to know the section.
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Old 03-12-2012, 11:12 PM   #10
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French drain pitch


French drains tend to silt up, if there is no slope the silt will plug then up over time.
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Old 03-13-2012, 07:41 AM   #11
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French drain pitch


For any sane person, the sump provides an air break between the "plumbing system" and a drainage system that is beyond the horizontal limits of the living space (exterior drain tile) or that is connected to an interior drain tile system that is outside the living space because of a elevation difference. Once the water is picked up by a sump pump(s), it may be under the plumbing code in some jurisdictions.

Is the control of the water flowing across a floor into a floor drain come under the under the plumbing code just because it runs into a pipe that may not be under the plumbing code? A drain tile system is intended to collect the water before that AND to reduce lateral pressure on the walls and floors and prevent structural damage. The 8,000,000 people in the city of Amsterdam (all below sea level for centuries) are there because they adopted the principles developed by the Romans and dewatered the city by using horizontal pipes and the soil to collect water and direct it into pipes for pumping away.

A journeyman plumber (union or not) is not qualified to specify the size of the aggregate of a natural subsurface drainage system even with a made up "standard" for aggregate particle size.

Even as a lowly professional Civil and Structural Engineer, I would not bother to comment on some plumbing eccentricities. However, I did work with a builder to develop a waterproofing system to never have a wet basement. He built over 3,000 homes without a problem over a 20 year span. All perforated PVC pipe was installed horizontally. Incidentally, this was before the use of filter fabric that can easily be misused and be detrimental in the end. Also he was 100% union and never had a plumber install any drainage pipe or "weeps/bleeders" because the union wanted to part of that work.

The ideal mix of aggregates that has been used for decades on golf course (without pipe) is a blens of clean sand, "pea rock" and coarse aggregate since it increased the collection area and does not clog up (without pipe) even with virtually level elevations of trenches.

Dick
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Old 03-13-2012, 08:07 AM   #12
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French drain pitch


Quote:
Originally Posted by Nailbags View Post
Well Here is my back ground I am retired Union Journeyman Plumber It has pipe it goes to a sump and it goes to a pump. It falls under the UPC and it is a 1/4 inch per foot. How hard is that to understand. It seams like that when some one points out something that they have knowledge on you seem to come back very insulting. I am not even going to second guess you on mason work or cement work why It is work I don't do. I gave the man the correct information. and BTW yes the Aggregate does need to be specific sized at least 5/8th min. That way the drain does not fail in a few short years.
Have a link to that code?

BTW, the masons/foundation contractor's are the individuals responsible for installing all the interior & exterior draintiling that goes to the sump crock. The plumber has nothing to do with it. And, 1/4" per foot would be far too drastic for most homes, or they would need a sump crock every 40-50'.............

PS, hate to say it, but you're incorrect on this one.

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