Dry laid stone wall construction

[steveair]

hello,

Just seeing how you guys build stone walls that act as retaining walls.

Just got a design/possible install for about 250 ft of wall and want to make sure I think it through right.

Half of the walls are going to be under 2 ft, so I'm not too concerned with how 'heavy duty they are. I will still back fill with lots of 3/4 gravel for drainage, but am not too concerned.

As for the other half, they will be in the 3-4 foot range and need to be durable. I was thinking about building the wall about 2 feet thick at the bottom, tapering to about 18 inches at the top, with a 3 inch batter from top to bottom.
They are going to be located at the bottom of a inclined planting are, so the load on them will be signifigant. I may have to go higher, but am not sure untill the site gets leveled, trees cleared, etc.

Does this sound right? I'm not sure of the stone exactly yet, but will probably be a field stone type wall, with pieces in the 2-4 inch thick range.

I hate seeing people put all the time in to build a dry laid stone wall only to see it start leaning a few years later. I don't want that to happen. I plan to back fill with a lot of 3/4 crushed for drainage, along with a perforated drain, and maybe drainage fabric?

Also, what kind of footage do you guys get out of a typical pallet of wall stone (3000 lbs) I guess its hard to desribe as types of materials vary, but just asking. I have always figured I get about 10 face ft of wall out of a typical pre-palletized/stacked pallet, with a large percent of the stone being unusable (seems like they put all the pretty stones on the outside and fill the center with garbage) Also, what kind of pricing. I try to get about 400 for every pallet, or around 40 a face ft for dry laid work. How does this compare to any of you out there?

steveair

[Edited by steveair on 10-21-2000 at 11:16 PM]

[Stonehenge]

I need to first clarify what type of stone is being used. When you say 'fieldstone', I think of the stones a farmer finds in his fields; rounded boulders of varying sizes. When you say 2-4" thick, I think of a quarried stone (limestone is most abundant here), snapped into rough dimensions. So for my response, I'm assuming limestone.

Because they don't have the same uniform shapes and full contact with the surfaces above and below each piece like a Versa-Lok does, you might consider more batter than 1" per vertical foot. For me, using limestone 4-5" in height, I have a batter of about 1" per course. Another thing that helps is to pitch the stones into the hill you're retaining - so when you set a level on the top of the wall, perpendicular to the wall, 1/8-1/4 bubble is to the bottom of the slope.

Now, if the stone you're using is much more uniform - perfecty flat, uniform heights, you can get away with less of all that.

Deadmen or tiebacks can help, too. As for grid, I haven't done enough big projects to speak with any authority about that. Paul would be your guy for that.

[paul]

Steveair I would need to know what kind of stone you are using to help you, rubble stone or cut flagstone

[steveair]

hello,

I don't know if it has a technical term, but I've always used the term Pennysvannia fieldstone as do the sellers, being that it is from PA.

Pieces average in the range of 1 inch thick to about 3 inches thick, and are somewhat flat, but also irregualar. They are naturally formed, not snapped as you may say.

This is one of those 'gaps' I guess we have in this business. Like trying to describe paver base course material. We probably all know what it is, but have a hundred diff't names for it as it is from diff't parts of the country.

[paul]

We have a rubble stone that is 1" to 3" about 4" to 18" wide and 12" to 18" long, installed in a random pattern. We don't like to use it on high walls too many surfaces that can shear. If it was for my house I would use a outcropping stone 4" to 6" thick 3' wide at the base, tapering to 24" at the top, with random lenghts, and set back 4" to 6" for each course. Bury 6" and run with it, use a fabric behind the wall with gravel between the fabric and wall stone. This way you won't need any pipe behind the wall. This should give you the look you want, plus it is more stable than rubble stone. You can go with a thinner material and do the smae thing just to my eye thinner materiel dosn't have the look of a bigger stone.

[Lanelle]

I use the same type of stone and we usually don't go more than 2 feet tall with it. I know that it can be laid taller with the proper base thickness and stablization. If you buy directly from PA. source, ask them to advise. I know that owner of the quarry I deal with has been building large dry-stack walls for years, but there is definitely some skill involved in those big walls.

[Stonehenge]

Paul, I'm with you on stone size (and the stuff I use is much smaller than what you do) - the little stuff starts to look like play pebbles when you're used to bigger stuff. My favorite is limestone outcroppings, 500-1000# each.


Just some engineering info to toss out there - a civil engineer at Versa-Lok said in a seminar last year that they've stopped recommending fabric between the stone and the soil you're retaining. The reason being the fabric you're using is intended to prevent fine soil particles from getting into the stone and clogging it up, preventing drainage. They were finding that with the fabric installed, the fabric was getting clogged with fine soil particles, resulting in the hydrostatic pressure you were trying to avoid in the first place. Their recommendation: no fabric, 1' of 3/4" clear crushed stone behind wall feeding to 4" corr perf pipe behind wall at grade, daylighted somewhere in the wall where it can drain freely.

[osc]

Check out this link and look for the tips on retaining walls: http://www.langstone.com