I’m hiring a landscaper to build a dry stack retaining wall that’s about 2 1/2 feet high. He says it doesn’t need a footing of gravel because it’s so low and the rock isn’t that heavy (25-75 lbs per rock). There’s also no real need for drainage.
Is he correct? I thought these walls needed some kind of footing.
From building boxes and fitting face frames to installing doors and drawers, these techniques could be used for lots of cabinet projects.
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Replies
There are a lot of variables re soil conditions and slope.
So a lot depends on his experience and reputation.
And you know more about both than I do.
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What kind of stone? Boulders? Flagstone? If boulders, some settling won't show, but flat stone stacked up needs to be level to look good.
We use a 6" tamped crushed stone base on even an 8-10" wall. At two and a half feet, I would also use geotextile and washed 2" stone with a perforated drainline. But I like to do it right. :-)
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2½-feet high isn't much; unless there are serious amounts of water that will wash through the retained soil, you could be okay. Do make sure he slopes it back enough so it won't topple. For a wall of that size rock at that height, I'd slope it to put the top about 12" inwards of the bottom row. (And the bottom row should be dug in, of course.)
It also wouldn't hurt to ask him to lay a geo-textile behind the rock as he backfills; this can be especially important if the soil is sandy. Without it, you can lose your fill through the interstices between the stones.
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Footing is not required. but the first layer should be almost flush with the existing grade. The first layer generally is the repository for the big ugly rocks that came in the load. Backfilling with light gravel or porous coarse sand at each layer is essential. You need drainage as well as a stable base for the rocks on the next level.
I built 100 of these working for a landscaper in Michigan. Generally in native stone you want to choose flat rocks of some type that are wider than 12 inches in depth unless it is a really short wall. Short is less than 2 feet. The backfill needs to be made at each layer as you go. The next layer steps back minimum 2 inches and repeat as necessary. That'll work for hard soils up to about 4 feet.
After 4 foot you have to get serious. Still no footing but the base has to be of thick (6") and wider thicker rock for a stable base. Generally a "dead man" is required for loose soils which is a RR tie cabled at each end and buried back a way up the hill to provide an anchor to keep the top from falling over. Cable end is secured in some novel manner to a big rock several courses down from the top.
Like someone wrote... a lot depends on the soil. Note that it is supposed to move, drain wnr grow vegitation. Otherwise get a mason and put up a block wall. That is a whole nother kettle of fish.
This may be bad protocol on this list-serv - don't know - but THANKS so much to all of you for the thoughts. Really helpful!