I have a large boulder retaining wall, both the wall is large and the boulders are large, and a question on filling the gaps between the rocks. The house and wall are 25 years old, we moved in a year ago, and there are some rocks that have decent size gaps between them that is allowing the gravel back fill to wash out. What are some good ways of correcting this as to stop the wash out?

My thought was to power wash the spaces between the stones to get the loose back fill out then to 'tuck' in concrete to plug the cavity.

Any suggestions would be appreciated. Thanks

 

How high is the retaining wall and what is the ground like behind it? How large are the rocks forming the wall? How much work are you willing to expend to repair the wall?

Generally I don't think it's a good idea to concrete or mortar on a dry stacked wall. It might be OK to do here and there but you don't want to seal the wall up or try to stick everything together. Dry stack (no cement or mortar) walls benefit is that they can move as the ground settles and water trapped behind can percolate through. Properly filling the openings with stones would be the better option.

 

I have just completed (yesterday) a major landscaping project using large boulders (100-800 lbs ea) so I think I have a little experience with this. Our soil is very sandy and I used the recommended fabric behind the boulders which is an 8oz landscape/erosion control fabric. It is a non-woven fabric that will let water through but not soil.

Your best option is to remove the boulders, install the fabric I have mentioned, and then reinstall the boulders. Likely this is not an easy option, but another option is plant something that likes to grow in the cracks of stone walls (search "boulder wall plants") The plant roots will take hold and help prevent the erosion. You might want to stuff the holes with some good dirt to give the plants a start. You could also add some smaller rocks as Dane suggested and the plants for a combo effect. This is what I am going to do to hide the fabric from the sunlight.

BTW - here is my wall:

 

What are the terraces for? Do you have a moat in one of them Nice wall. Glad your back did it and not mine.

 

The top one will be for a brick patio and pergola. The middle one is for a fire pit/ sitting area. The bottom will just have small bushes and perennials.

I can not lift 800 lbs. Tractor did most of the work and a Bobcat for the dirt moving.

Thanks

 

Nice workmanship with the boulders, but I don't care much for your design. Having straight, uniform-looking lines with large, natural stones is too unnatural. Would have looked much nicer if you put in some gradual curves and even vertical relief. Making it look like the stones were placed by nature (instead of a man and his tractor). A few steps near the center at each course would also have made things more practical, to avoid walking all the way to the ends to go from one level to another.

 

It is hard to tell form this picture but there is a stairs from the top tier to the middle tier by the steps from the deck. That will give access to the firepit. I was limited on how many stairs I could build by how many flat rocks I got. There is really no reason for for foot traffic all the way down as there is nothing to go to.

Were getting a little too here but one of these days I will post something in the "I did it myself" section. Let's just say I did the best I could the what I had to work with.

 

Isn't that what all us diyers do?

 

I hope you had diesel power to help move all those stones. Since I've gotten my little track hoe with a hydraulic thumb I've become rather lazy.

 

Mostly there are rocks that are 3' to 5' across and I would assume several hundred pounds.
Also thanks for thread-jacking my post. Ha

 

I don't think those rocks are anywhere close to a few hundred pounds. I'll bet many/most of those rocks have a comma in their weight. It does not look like you'll be able to do much removing and re-building without getting into the footers for your deck.

First, I'd extend the downspout drain pipes to beyond the rocks. I might then try packing gravel back into the areas that have washed and jam some larger rocks in to help hold things in place. Concrete might work but I don't think it would look good and might not hold up well to freeze/thaw movement like rocks would.

 

I would agree with Dane. My rocks largest rocks were about 3' dia and my tractor could barely lift them enough to skoot them around and the tractor is rated at 800lbs lift. Yes, it is diesel.

I think some good ground cover plantings would be a big help. I also agree with Dane about the downspout. You have a nice natural look to your boulders, (Unlike mine, ) I think concrete would mess that up.