# uderground downspout extensions



## ALPS (Jul 28, 2006)

I need new gutters and was considering running extensions off the downspuots underground to discharge the runoff even further from the foundation.

what should I use underground?  PVC?  How deep should it get burried?  What do I do at the end of the run?  One side could reach the driveway, the other will be out past some very large maples.


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## MTCquality (Jul 29, 2006)

Corrugated plastic drain tile is best but if PVC is in your budget then by all means go for ir. make sure you have a good grade.


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## glennjanie (Jul 29, 2006)

Hello ALPS:
In my experience the corrugated plastic pipe becomes blocked too easily with leaves, pine needles and such. While smooth PVC pipe lets this sort of stuff on through. You could use PVC-SDR 21 or PVC Schedule 40 ( the later has thicker walls and is more crush resistant). The pipe is not very expensive; its the fittings that cost so much. The SDR 21 has the coulplings built in on one end of the length of pipe.
Glenn


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## glennjanie (Jul 29, 2006)

Hi ALPS:
Let me try again, I didn't answer all your questions.
The pipe could be 18" to 24" deep  to the top of it. Freezing is not much of a problem with this kind of pipe because it is an intermittent drain. On the end of the pipe I would use 1/4" Hardware cloth (which is actually a wire screen with 1/4" squares). The pipe should be cut to the contour with the ground then wrapped with the hardware cloth to keep rodents from lifting a corner and making a home in the drain. Cutting it smooth to the coutour of the ground will keep a mower from hitting the pipe.
Glenn


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## ALPS (Jul 30, 2006)

glennjanie said:
			
		

> Hi ALPS:
> Cutting it smooth to the coutour of the ground will keep a mower from hitting the pipe.
> Glenn




So at the end of the long horizontal run the pipe should 90 back up vertically and end at ground level?  Wouldn't this act like the trap in your sink drain and never be complety drained and dry?  I'd be concerned with freezing and cracking pipes.  NYS gets cold.  

 On the one side of the house I could run it in to (under) the drive way and dig out a dry well into the drive way.  Would that work?  We have clay soil that drains slow so the dry well might fill up with a heavy rain.


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## Square Eye (Jul 30, 2006)

ALPS said:
			
		

> So at the end of the long horizontal run the pipe should 90 back up vertically and end at ground level?  Wouldn't this act like the trap in your sink drain and never be complety drained and dry?  I'd be concerned with freezing and cracking pipes.  NYS gets cold.
> 
> On the one side of the house I could run it in to (under) the drive way and dig out a dry well into the drive way.  Would that work?  We have clay soil that drains slow so the dry well might fill up with a heavy rain.



Hey Alps!

By cutting to the contour of the ground, he means, cut the horizontal pipe at a long sloping angle to match the slope of the ground at the exit. This will keep the lawn mower from hitting it.


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