help w/ stone veneer on concrete block retaining wall
About a year ago I had a landscape contractor install a concrete block retaining wall in my backyard. At the time, it was all I could do to pay for the grading and block wall, so I'm just now getting around to applying a natural stone veneer and capping the wall (it's only had a makeshift cover of ceramic tiles that I laid over the top course of block for the past year - hopefully, I haven't severely compromised the integrity of the wall by doing this?) I've read various masonry books and info I've found online on do the stone veneer and, of course, I've ended up w/ different takes on some aspects of the process. Advice from someone who actually knows what their doing would be especially helpful! 1) Most of the books I've read suggest that it's okay to cap off the wall w/ some kind of capstone set in a mortar bed so that has a slight overhang extending beyond the veneer. In one book, however, it suggests that you cut a groove w/ a circular saw parallel to the edge of each capstone on it's underside to help it shed water. On a professional mason's website, I also read that he actually covers the top course of the wall in copper flashing (expensive!) and then sets the capstone in a mortar bed on top of the copper flashing. Are either or both of these necessary? 2) In some of the books they suggest nailing up wire mesh to the concrete block, applying a scratch coat of mortar over the mesh and letting it dry, and then applying the veneer. Are either or both of these steps necessary if you already have a block wall under there to adhere the stone to? Thanks for any advice anyone has. I'm open to any and all suggestions at this point. If anyone knows of a good reference on apply a stone veneer I'm all ears. Thanks. Alex Each manufacturer will have instructions for the stone installation over CMU, but basically you can just stick them to the clean, un-painted surface with a good mortar. As for the cap, if the wall was constructed properly, then any cap will do. By properly, I mean solid grouted with a waterproofing material on the soil side. If not, then it still doesn't matter, because you will have moisture in the wall in spite of the cap. Thanks so much for your input. I'm planning to use real stone as opposed to manufactured stone - so there's no manufacturer's instructions per se. I think the delivery guy from the stone yard will just deposit them on the pallet and leave me to my own devices. Glad to know that those other steps w/ the wire mesh/scratchcoat are not needed and any cap will do if all else was done right. I'm hoping the wall was properly constructed - there's a gravel filled trench covered w/ landscaping fabric behind the wall w/ a drainage pipe in a sock that drains to the outside. No weep holes, though. The mason insisted they weren't necessary. Some of the block webs are reinforced w/ rebar. Not sure if there is any kind of waterproof coating on the rear of the wall or not? I don't remember anything else back there other than the drain. I truly hope this wall outlasts me as it's the most expensive thing I own other than my house and I plan on living in this house the rest of my life. I will repost in 30 years w/ an update on it's durability. OK, you are confusing several things here, or I am. What is the thickness of the stone you want to attach to the wall? Hmmm...the stone yard hasn't delivered the stone yet, but I believe it's 1-2 thick. The guy at the stone yard gave me a deal on some sawn thin veneer that was cut a bit too thick at the quarry. It's *supposed* to range from 3/4-1 1/4, however, they cut it too thick for it to pass code for residential applications (it's supposed to weigh less than 15#/sq ft when used as veneer on a house and this would exeed that requirement). The stone yard guy said that wouldn't matter for my application since I just have a stone retaining wall to face. The other question I'm running up against is what mortar mix to use. Every time I read a different book or article I get a slightly different mix - so I guess there's more than one right way. Some say just to use straight Type S mortar, some to mix Type S or N w/ varying amounts of sand. Not sure which way to go on that. It is going to be hard to lay.. You will need to use a latex modified thinset and spacers. I use linoleum tiles broken into small pieces. You will also have to lay from the bottom up and be careful with the thinset. Mix the mud pretty dry and make sure there is no dust on the backs of the stone. Thanks for the advice. I will be sure to have some spacers handy. So, you're suggesting I use a latex modified thinset instead of some regular kind of mortar to get the veneer to adhere? Like the stuff you might use in a wet, ceramic tile installation? I read that some veneer manufacturers suggest you add an acrylic bonding agent to the mortar. Are those two things comparable? Yes, but standard mortar sand will have too much buildup. Use the thinset. Gotcha. Thanks for your expertise. It'll be interesting to see how it goes! imho, type 's' mortar with latex or acrylic additive will work just fine. i've laid 3-4 thick veneers with it, but that was real stone, where the stone veneer is actually laid as a separate wall, and you set the stones on a bed of mortar. mixing tip, no matter what you get: buy or rent a 1 drill with a plasterer's cage whip (not the two-paddle kind.) put two inches of water and your additive in a 5-gallon bucket, add half of an 80-pound bag of mortar mix, whip to a workable consistency, adding water or dry mix as necessary. cheaper than a mixer, easier than a hoe and wheeler, and it gives you a nice, workable amount. and if you eff it up, you can put it back in the bucket and re-whip it.
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