I have begun (laid a total of 4 boulders.) About summer time last year I started re-shaping my back yard. I am ready to do the retaining wall and have 40+ tons of boulders waiting for me in the side yard. So I laid in the biggest boulder (I reckon 600#+) and a few others and called it a day. However... My plan was to dry stack, 4' high, and do a gentle batter tapering back. I did not plan on any fabric or even gravel backfill/ base. The material being held back is extremely sandy. I fear the soil will just erode through the wall, eventually settling all funky and perhaps pushing the wall out without any drainage barrier. Should I use geotextile fabric & gravel? Pics do not show my "progress", and sadly those 4 huge boulders I laid are going to have to come out in the event I need the gravel & fabric.
How much area will drain "into" the wall per linear foot of wall? There's no magic number here....but when in doubt backfill the wall with gravel.
Im not a professional so take its worth but I would absolutely lay a fabric behind the wall backfilled with gravel. A drain behind would not hurt.
Talk with mywaynow, he built a beautiful dry stack retaining wall several years back and he did drainage. I'd say if it were my project, I'd definitely be doing fabric at the very least, and stonebed/drainage pipe if you get a lot of water in the yard.....
That makes 2 of us, but I will forego the drain as the dry stack should self drain provided the fabric & gravel are filtering the silt. Ayup, about this much give or take 5000% Yeah, but you're Mr. Overkill so.... Thanks fellas, you guys all willing to work for beer & bbq? How's this weekend sound to start?
Yeah - do the fabric etc. My last house we dry stacked boulders for several retaining walls (I'm talking about tonnage here had to use an excavator to roll them). Even those get moved by the "flowing" earth after a while. and before that, the clay/dirt/whatever, was flowing thru the cracks no matter how much filler rocks were used. Drainage however, shouldn't be a problem if you use fabric with the dry stack.
About halfway there with trench, will call for gravel this week and bought the fabric. I want to do this ONCE! Will create a separate build thread later on, thanks for the advice.
These are only my thoughts. Pull up any of the well know brand name dry stack wall manufactures web site and download their manual and follow their recommendations. If you can not find it, I have the Keystone manual if you PM me your email. I know that they are not typical retaining wall block but the same hydraulics apply to any retaining wall - water behind a wall is bad.... I would do 6 inches of 2b limestone/dolomite/or what you have in your area in the base tamped very well with an inch of manufactured lime stone (almost like a heavy sand) on the top and tamp again. The 2b stone can be use for the back fill also. Do not use any kind of round gravel. 1st layer of stone and set them with a 4x4 , log and sledge. Fabric directly behind the wall- some holes may be large enough for stones to fall out ->drainage pipe at the base of your 2nd layer ->1 ft of stone behind the wall then mesh again- that way the stone does not fill with sand/ silt / dirt. Build the wall up a couple levels, back fill stone , pull the back fabric back over the wall , back fill dirt, pull fabric back off the wall up the hill and repeat until the wall is at height. That way you can manage how much stone you put behind the wall - too much would be just an extra expense. I did these 2 walls. I don't do it for a living but try to do stuff up to spec when I do things. We have had some really bad below zero years recently and hard freeze/thaws and no movement on either wall. Forgot to mention - they have 6 ft fabric - it is more expensive but higher grade and much nice to work with. Again, these are only my ideas. Hope I was able to help.
ChipsFlyin love the walls and I understand just about all your advice. Why no "round" gravel? Was planning on 1 1/2" minus gravel for the base and backfill.
round can move especially on the base. The sharp stone locks in place when compacted. From the installation manual. "Install Unit Drainage Fill/Backfill and Compaction. Once the pins have been installed, provide ½-¾ inch (10-20mm) crushed stone unit drainage material to a minimum total distance of 24 inch (610mm) from wall face. Fill all open spaces between units and open cavities/cores with the same unit drainage material. Place the wall backfill behind the unit drainage fill in maximum 8 inch (200mm) lifts and compact to 95% Standard Proctor Density or 92% Modified Proctor Density with the appropriate compaction equipment. Use only hand operated equipment within 3 feet of the retaining wall face."
