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Green Grass
04-01-2006, 10:52 PM
Hey i do lawn care and irrigation for a living. But i have to build a bolder wall next to my house i was wondering if there are any secrets that i should know.

Jamesgateslandscaping
04-01-2006, 11:34 PM
What size boulders? We did one last year, 2-4ft diameter rocks, they were huge and offset them so that they would interlock w/ each other, came out very nicely. Here are a couple pics.
James

Jamesgateslandscaping
04-01-2006, 11:35 PM
And another....
James

randallwise
04-01-2006, 11:43 PM
I would say it depends on the height of the wall. Can't go over 4' as you probably know. Anything over 4' and you'll have to have it engineered.

Dirty Water
04-01-2006, 11:56 PM
I would say it depends on the height of the wall. Can't go over 4' as you probably know. Anything over 4' and you'll have to have it engineered.


If you have to go over 4', find out how far back walls have to be set back from each other in your area's code, and build two 4' walls on a terrace.

olderthandirt
04-02-2006, 12:13 AM
Each rock was between 4 & 5 ft. set the top course back in 12" from the bottom when there this size. They wont move

JimLewis
04-02-2006, 03:28 AM
Well, it depends on what size of boulders you are referring to. There's a big difference between building a wall like the ones in the pictures above (using very large boulders that are moved around with a large track-hoe) and a wall using 1 or 2 man boulders that you can lift and move on your own.

See my website below. Check the pictures section. We have a section there just for dry-stack rock walls using the 1 and 2 man smaller boulders.

Anyway, some basics; First, you'll want to prepare the ground properly where the wall is going to be placed. Excavate below grade several inches. And excavate back a foot or so from the back of the wall. This is because you'll be backfilling with gravel, for drainage reasons. Anyway, then you install and compact several inches of gravel as your base. Then you start to lay your first course of boulders. This first course should be partially buried - below grade. This stabilizes the wall. Then you start to stack and backfill. Stack and backfill. It's like trying to fit together a puzzle only the pieces are from different puzzles. So you just keep trying and trying different boulders until you find two that fit well together. After a while it becomes easier.

Do the first course first. Backfill that course as you go along. Then start the next course, and backfill again as you go along. The backfill holds the boulders into place so they don't fall backwards.

Also, study about the concept of batter. You want your wall to pitch back a little bit as it goes up. That keeps the rocks from falling forward.

You'll want to have a wide variety of boulders at your disposal as you build the wall. So get more than you need. You can always return or save what you don't need. But the more options you have and the more pieces you try in each area the nicer the wall will turn out.

That's about it.

treedoc1
04-02-2006, 11:33 AM
I just stacked these with the dozer so I didn't have to keep cutting back from the house I'm building. Not much movement with these...most are at 6-8' tall. Not as pretty as the ones purchased from the quarry, but I was just trying to get the house done and use up what was on site....function first. Work from one end and go back across the face. Good batter angle is important.

GreenMonster
04-02-2006, 11:54 AM
I would say it depends on the height of the wall. Can't go over 4' as you probably know. Anything over 4' and you'll have to have it engineered.

I didn't know boulder walls had to be engineered if they were over 4'.

How do you engineer a boulder wall when each boulder is unique?

sheshovel
04-02-2006, 12:54 PM
treedoc I call that RipRap

treedoc1
04-02-2006, 01:20 PM
Venice Beach Rip Rap for you Californians.....rip rap on steroids:weightlifter:

Green Grass
04-02-2006, 02:36 PM
I am building a wall that will be about 4ft at the highest point. the boulders are about 2 to 3 feet in size have to use skidsteer to move the boulders.

randallwise
04-02-2006, 03:59 PM
If you go over 4' you will have to use a material other than boulder, such as locking retaining wall block, which will have to be engineered.

JimLewis
04-02-2006, 08:25 PM
If you go over 4' you will have to use a material other than boulder, such as locking retaining wall block, which will have to be engineered.

I am not sure that's true. I've seen lot of walls in my area using the large boulders that are over 4'. Some of them in my area are over 10 or 15'. And I always wondered how they got away with it because my area, like most, has codes that say walls over 4' have to be engineered. And you also have to get permits and inspections on them. And these walls are in areas where inspectors are driving around on a weekly basis. So I know they must have been approved. But how do you engineer a boulder wall? I don't know. But there must be some way to do it because I see it quite often around here.

randallwise
04-03-2006, 12:36 AM
Yeah, I've seen big walls in this area, but anymore, it won't happen. Here they had to have been built before the code changed. Especially our county, anything over 4'1" and they nail you. But no, boulder walls can't be engineered as they do not lock well together (so say the engineers).

PSUturf
04-03-2006, 11:11 PM
We use black fabric behind most of our boulder walls to prevent soil from bleeding through. The guys that do the walls do such a good job of placing boulders that you hardly ever see the fabric. We often do walls over 4' and never have them engineered although that might not be the case with commercial jobs. I don't work on those.

klkanders
04-04-2006, 12:00 AM
PSU
Same here. We set the bottom layer on fabric and step it up each layer backfilling to hold boulders in place.
Some advantages of boulder walls are they are easier to step down with grade and also dont have to worry as much about settling next to new foundations.