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Discussion in 'Hardscaping' started by alldayrj, Aug 19, 2012.
Oh, glad I read this before my job tomorrow lol. I've been mulling this over in my head all day
Hold on a second, guys. I'm just an amateur builder (4 small walls for various family) but I use this website as a resource to further my knowledge and ensure I'm building structures that will still be standing 15-20 years from now. I have the following concerns with Alldayrj's design and construction. These concerns may not be serious design flaws, but I think you guys, the professionals, owe RJ a more critical review of his work.
Issue 1. No geogrid reinforcement. The wall is 3.5 ft tall. The retained slope behind the wall appears to be or exceed a 3V:1H grade. The slope alone should require geogrid reinforcement. Of all the gravity wall spec's that I've seen from Versalok, Keystone, Allen, Techo, none of them allow a gravity wall above 3ft with a retained slope of that magnitude. I couldn't find the .pdf but I can't imagine that Cornerstone, which I think he used, would approve of this application of their block. DVS,any thoughts?
Issue 2. First course not buried into undisturbed soil. Just piling soil up on the face of the wall and compacting it down does not seem to provide the same level of resistance to kickout as burring into virgin soil. I know DVS said that sometimes the patio can help add reinforcement, but it would seem to me that any movement of the wall would just cause lifting/buckling of the patio surface.
Issue 3. The leveling pad looks to be inadequate. In addition to the concerns mentioned above about not burring the 1st course, the picture does not seem to show a minimum 6 inch deep, well compacted leveling pad. Again I may be mistaken. I think a location of Queens, NY would experience alot of freeze thaw cycles, perhaps some winter melt followed by a hard freeze. My worry is without a deeper, well draining leveling pad the wall may subject to heaving or, in the case of leveling pad degradation, the wall may sink in some area.
Please understand that I'm not attacking RJ. It just seems to me that some of the basic construction practices that have been discussed in great detail on this forum have been disregarded on this project and I would like the professionals to take a moment to discuss.
thanks for the thoughtful post, I appreciate it and thats why i posted pics. and to show off my sweet set of tools.
the base is definitely adequate, I didnt show the excavated footing but there is 6" there and its tamped well. also, we took the whole grade of the yard down so its pretty virgin. the dirt we did add back to the face was also tamped.
the slope behind the wall I'm curious to learn more about, as well as terracing walls ( the neighbor wants one)
the block is libertystone 6" mirastone, it was great to work with
All of the force of that slope is pushing on the first course of you wall, hence the importance of burying one full course.
For a terraced wall if you dont set the upper wall back 2x the height of the lower wall, it acts as a single taller wall and would need to be engineered as such.
looks good but my thought is that geo grid is cheap insurance but my other thought is geo fabric between base material and sub soil. It is specs for under patios why not walls? I am also a big fan of using it under base rows. If anyone knows any conflicts with doing that please tell me.