# dry stack natural stone retaining wall



## diy001 (Sep 25, 2009)

I am in the process build a 2.5' dry stack natural stone retaining wall. do I need to put drainage pipe behind the wall? Most of articles online say no need the drainage pipe because water can flow from the wall. I agree with this. How do you expert's opinion?


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## Bud Cline (Mar 12, 2006)

We would always bring up the dirt fill with the wall and place white rock behind the stone as we went up. A plastic barrier was also used behind the wall. This way the earth has an opportunity to expand and contract without torturing the stone wall and any dirty debris that comes along will filter downward. I also always wanted to cant a wall 5 degrees if it was higher than four feet.:yes:

No drainage pipe is necessary as far as I'm concerned.


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## CplDevilDog (Mar 18, 2009)

Plastic? At the risk of showing my ignorance here, I think filter fabric is the best course.

It will filter your fines out before they get into your gravel drainage plane but allow water out of the bank, reducing pressure.

I agree, no weeping pipe needed in drystack


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## CplDevilDog (Mar 18, 2009)

p.s That's going to be one beautiful wall. Where did you get the stone from?

Don't forget to post your after pics.


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## diy001 (Sep 25, 2009)

Bud Cline said:


> A plastic barrier was also used behind the wall. This way the earth has an opportunity to expand and contract without torturing the stone wall and any dirty debris that comes along will filter downward.


I guess you mean a fabric filter layer should be installed between the 3/4" crashed stone and the soil. The crashed stone should be put between the wall stone and the soil. Am I right?


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## diy001 (Sep 25, 2009)

CplDevilDog said:


> p.s That's going to be one beautiful wall. Where did you get the stone from?
> 
> Don't forget to post your after pics.


The stone is from somewhere in New York state, I think. We bought from a local landscape supply store last winter. we like it.


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## diy001 (Sep 25, 2009)

My wall have a short turn at both sides. Which way I should go at the turn?


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## CplDevilDog (Mar 18, 2009)

I would weave your corners.

Alternate long stones on each course

You are correct, your crushed gravel should go between the back of your wall stone and your filter fabric which should lay on your dirt.


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## user1007 (Sep 23, 2009)

That is going to be a nice looking wall. I agree you do not need a drain pipe but given the money you have in stone are you sure you don't want to spend a few bucks more for one for added peace of mind during the next storm of the century? I really am not one for wasting building materials so am just throwing the thought out for you to think about. You have everything excavated so no real extra labor involved in adding the drain?


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## Bud Cline (Mar 12, 2006)

> *I guess you mean a fabric filter layer should be installed between the 3/4" crashed stone and the soil.* The crashed stone should be put between the wall stone and the soil. Am I right?


I said plastic and that was a little misleading. The product we used is plastic but with millions of tiny slits in it for water and moisture to pass through it.


> I guess you mean a fabric filter layer should be installed between the 3/4" crashed stone and the soil. *The crashed stone should be put between the wall stone and the soil. Am I right? *


Correct.


> My wall have a short turn at both sides. Which way I should go at the turn?


The corners should interlock.


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## GardenConcepts (Jan 21, 2010)

I always use 4" perforated pvc behind dry-stacked walls- any water sitting at the base of the wall will drain away. I also like to put 1-1.5" of batter on the wall for every 12" in height. I also cut back the grade behind the wall, beginning at the base of the wall at about a 25-30 degree angle to reduce pressure on the wall, backfill with lots of 3/4" clean stone and rubble. Geo-textile should always separate the gravel from the soil.


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## diy001 (Sep 25, 2009)

GardenConcepts said:


> I always use 4" perforated pvc behind dry-stacked walls- any water sitting at the base of the wall will drain away. I also like to put 1-1.5" of batter on the wall for every 12" in height. I also cut back the grade behind the wall, beginning at the base of the wall at about a 25-30 degree angle to reduce pressure on the wall, backfill with lots of 3/4" clean stone and rubble. Geo-textile should always separate the gravel from the soil.


 looks like there is another professional expert. that 4" perforated pvc should be installed at the very bottom (first course) of the wall or at the base of the wall?


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## diy001 (Sep 25, 2009)

Thank you guys.

This is my design of the drystack stone retaining wall. please review it to see if anything wrong there. This retaining wall connects with a brick patio (my next project). 

We planned to have stairs in the middle of the wall to let us access upper yard more easily. My wife wants the stair to be built with the same material as the wall. this will be a challenge to me.


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## CplDevilDog (Mar 18, 2009)

Depending on how far north you are, your gravel base may be a little light. 6" is recommended here in PA.

As GardenConcepts said step your bank back to take pressure off the wall.

If your really feeling froggy throw in a French Drain under the patio to drain it.


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## CplDevilDog (Mar 18, 2009)

Sorry, but I'm not a believer in perf pipe for drystack. I'm all about the over-engineering but I'm not sure it would have any effect.

Typically you put perf pipe around footings and masonry structures to drain water that would eventually build up until it had enough pressure to push through your masonry wall and into your basement or into your masonry wall where it would freeze and crack.

With a drystack wall on a gravel footer, water is supposed to (and will) flow through the wall and under the wall and drain through the gravel footing. I guess if the wall was low down in a high water table area you could eventually pool enough water around the base of the footer to cause problems.

I've been wrong before and I'll be wrong again so there's a better than average chance I'm wrong now. Open to opinions


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## CplDevilDog (Mar 18, 2009)

So. this might be a nice compromise.

I beefed up your footer for the wall and moved the drain to the bottom back. This will let it drain both the wall and the patio.

I think the perf pipe has a place in the drystack walls as long as you keep it low. Raise it high and water will just shoot by.


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## diy001 (Sep 25, 2009)

CplDevilDog said:


> Depending on how far north you are, your gravel base may be a little light. 6" is recommended here in PA.


 I am in MA. So I should be the same as PA. But some places say there is no requirment on base of drystack retaining wall because the wall can up and down due to they are loosely coupled.


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## diy001 (Sep 25, 2009)

CplDevilDog said:


> So. this might be a nice compromise.
> 
> I beefed up your footer for the wall and moved the drain to the bottom back. This will let it drain both the wall and the patio.


I have pipe for patio by design. The patio will be surrounded by a french drainage system for sureface water to keep them out from my house.

You can see a black pipe there from my first and third photo. That french drain system has been done last summer but the portion close to the retaining wall will be done after the wall.


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