Please help me. I have a backyard with a slight slope (1 foot for every 8-10 feet) and I had it leveled in one area for an above ground pool. I had a local landscaper build a retaining wall. Well much to my suprise after they were done i discovered they did not set the blocks in 4" in a trench as I thought they would. The just leveled the ground with what looks like rock dust (very fine rock sype sand) and placed the first row of block on that. I called them to complain and they said that the weight of the wall would naturally push into the softer clay an inch or so and that the wall was rock solid and not go anywhere. They also said that the slope is very gradual behind the wall and that there would not be any pressure behind it that would push it out. They filled with crushed stone 18" behind and put in a 4" drain tube behind, although it sits about 4" above grade behind the high part of the wall. I do not know what to think at this point. From the picture, would you expect it to slide forward or may I be okay on this one. Other than taking the whole wall down and resetting on a new foundation are there any other methods to create a strong barrier in front of the wall to keep it from sliding? I am putting an above ground pool in the center and will have 3-4' space between the pool wall and the block wall. I am in Tennesse and do not experience significant groupd frost/heave. Thanks for any help/advice.
Last edited by nashvillewall : 07-28-2009 at 01:01 PM.
Reason: typos
Proper install includes embedment - if you want corroboration I'd suggest finding out the brand name of the block and checking the tech specs on their website.
As for what to do now - you could try installing paver edge restraint along the base of the wall. It's unlikely that would be able to stop any significant pressures, but it couldn't make the problem any worse.
You could also bring soil in and place it in front of the wall to a depth of 4 to 6" to provide embedment. This would have to extend out from the wall at least 3 or 4' which means that you would have to bring in enough soil to level the pool area. I also question if the contractor provided enough base for this wall.
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Thanks for the reply. I also wondered if I should dig out 8" in front and have concrete poured into the trench and bring it 2-3 inches above the bottom of the block. Will not solve any settlement issues I am sure but may prevent it slipping forward?
Here is what the contractor has come back with for a remedy versus tearing down the wall and resetting the base block in a trench.
"If we were to rebuild your wall, the block would be approximately 3" below grade. Instead we would lay pavers that are 2 3/8" thick in addition to a crushed stone base. This would be in the three feet in front of the retaining wall. This should be more than efficient for you concerns."
gun to my head, I think your okay. I would avoid the concrete. Make sure any down spouts from the house do not drain toward the wall as well as control any major surface water behind the wall. The pavers should do the trick, the wall isn't going very far if it moves.
I would have done the base right, always do the base right, but I do agree that your concerns are probably 10 years down the road. The cheapest solution to address your concern would be to bring in the dirt. Don't let the guy sell you any freaking pavers. He's upselling you on something else to cover his butt. Sure, it would be nice to have a little paver "decking area around the pool, but it's a way to make more money. Of course, I am assuming that he is asking you to pay for those pavers, right?
So here is his latest proposal. He will come in and lay 12" of rebar reinforced concrete along the front of the wall. It will be 8-9 inches below grade on compacted rock and will stick up 3-4 inches in front of the first row of block. This should prevent any forward slide in the wall, which is my biggest concern. He will also give me a 10 year warranty that the wall will not move or settle out of level or placement more than 1/2 inch. Sounds like a reasonable request versus redoing the whole wall. Not sure how this would be cheaper than just redoing the wall and setting the blocks below grade as he should have. This is all at no cost to me. Thoughts?
I spoke to a lawyer and the lawyer says I have to give him the option to make it correct and give him one chance to do that. My contractor who built the wall says that because the dig into the slope is very fresh from last week and that the very dense clay is already compacted so hard from being 2 feet underground for many years, he is very confident that going down the 8-10 inches will not cause an immediate failure of the clay base under the rock. He plans on building the concerete form, digging the trench, dropping in the rock base and rebar. Then pouring in the concrete the same day. He says he can have that all done in one day and that the concrete will cure very quickly. He said if IT DOES collapse into the trench from under the base rock then he will then revert to plan "B" which is rip it all out and redo. He is also giving me a written 5 year warranty for 100% replacement if it does not work or starts to shift.
Two other guys came back at a price of over 5 grand to tear it down and rebuild (using my blocks no less that are already paid for) with a 6" - 12" concrete footer underneath it. None would agree to just rebuild setting the first row of block in the ground because they said they just do not build them that way. I called the National Concrete Masonry Assn and talked to the Dir of Structural Engineering who teaches certification in SRW installs. He said that as long as the blocks are a minimum of 4-6 inches below grade for a wall of my hight and slope setting I would be more than fine. Do not see whay I can not fine a contractor who will not build/rebuild one without a concrete footer.
Guess I should have taken the time to build it my self over 3-4 weekends and then I would have known it was right since I always follow the MFG instructions to a "T" Lord knows I have learned more than I ever wanted to about these stupid walls from this experince.
Just an FYI, I spoke to our local concrete MFG. before putting up our retaining wall. He said that he's built 20 to 30 walls in our local area and says that putting wall up on a concrete base is a bad idea because the rock will slide and suggested (as above stated) to use compacted crushed rock /limestone base has a better hold.
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