Round Stone Wall Formula

Old 04-22-06, 02:37 PM
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Round Stone Wall Formula

Hey Folks
Looking for a formula to determine how much stone would be required to build a round stone retaining wall (mortar).
The wal will be about 78' long with some curves and 2'-3' high.
I called a local stone yard and the sales guy said it has never been done (yeah, not so confident in the stone yard anymore since the foundation for my house is made from round Deleware River Stone).
Anyway - I tried to come up with my own calculations, but wanted to run them by some folks who may have a clue .

I calculated that my total volume for the wall would be
175 cu ft

I got this from 78X3X.75 (I figured the stones would be about 8" wide and would fill in the back with cement and junk stone)
I was able to get some useful info out of the sales guy
the chunk rock comes on pallets about 4' wide and held together with chicken wire in a circle about 3' high

so in a pallet i would expect to get about
38 cu ft

this means I would need about 4.5 pallets of the stone.

Figure I would use 5-6 2 man boulders (150-500 lbs) as good foundations stones through out the wall for accent.

Am I even close here?

Thanks for the help
Old 04-22-06, 04:58 PM
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That is about what I would have figured.
Old 04-22-06, 08:39 PM
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Round Stone Wall Formula

I think you are very short on your calculations. You are dealing with irregular pieces and all variations (and there will be many)should be rounded up. If you are using mortar, you should make the wall as solid as possible and minimize the amount of mortar, especially since you are trying to build a rigid wall without a footing (assumed).

An average thickness of 8" is not reasonable for a 3' high wall. You are not going to reduce the thickness when the wall in not as high.

You have curves that add additional volume required.

It is possible to use a minimum of material by being "clever" with placement and end up with a poor wall.

When you build the wall, you are fitting and use as much material as possible for strength and durability. Apparently you are buying by volume on a pallet that is not as tight as your wall would be.

For estimating purposes, you should plan on 30% to 100% more volume that you get with a sharp pencil or calculator.

The volume of materials can vary by a large amount depending on how they are packed and the shape. This is especially true for angular materials.

An example - take a 4' x 4' x 4' box and fill it with 6" balls. That gives one one amount of material (solid). Add a bunch of bb's that fill into the voids. That gives you another amount of material in the same box. - Which box would your rather lift?

Old 04-23-06, 04:11 AM
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Thanks for the responses
I do plan on running a footing and the back half of the wall would be filled with junk (broken up cement, other rocks i have in the yard, gravel, and I planned on mortaring in 1/2" rebar both in the footing as well as the back of the wall.
Because it is a irregular shape I am using, I am having difficulty understanding the right balance between too much mortar fram a looks perspective and too little mortar from a strength perspective.

Too much - looks bad
Too little - might as well be free standing

This is why i figured the volume on the pallet would be about the same as the volume in the wall? I like the idea of adding 30%, but i guess i could just do that on the initial order and then if needed by enough to finish, figure by then i will have a good idea of how much it will take.

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