Hi all, several weeks ago I posted a question about a sub that was installing cultured stone on our walkout foundation wall. The question at the time was whether or not the stone could be slapped on to the foundation wall. The general I answer I recall receiving was ‘yes’, as long as it hadn’t been painted or anything – it hadn’t.
He subbed it out to another guy (I didn’t know he planned to do that but actually the second sub seemed a tad more dependable than the first so I rolled with it). Due to some unreliability of both guys (long story; my fault; cash deal), weather delays, etc. I haven’t seen either of them in a couple weeks. He was out there one night according to my G.C. but he didn’t get much done. Today both the G.C. and I were out there and noticed that about 8 of the stones had literally fallen off the walls. As we started tapping on the stones it barely took any pressure for them to fall right off the wall. The hardened concrete sticks to the stone but falls right off the wall as if someone had sprayed silicone on the concrete wall. Other stones (on other parts of the wall about 15′ away from the trouble areas) won’t come off if you kick them hard.
What could account for this? Could it be the mixture they used? How do we fix this? I’m assuming we have to chisel them all off and start over by putting mesh on the walls?
I called him but of course he’s probably out working on another side job as he rarely answers his phone before 10 p.m.
Thanks,
Rob
Replies
Could be the mix....should be type "S" mortar mix, which has a little richer lime component. (Go to the Cultured Rock website and look at the application instructions).
Could be that he didn't dampen the surface of the foundation....ya gotta keep a little spray bottle or sponge handy to wet the surface; otherwise, the surface you're bonding to will suck the moisture right out of the mortar and cause adhesion failure. Should also wet the backs of the stones.
I also add a little acrylic admix to each mortar batch, along with a little extra Portland cement....adds to adhesion and final strength.
These pieces should not be falling off. If done correctly, you'd have to chisel them off in chunks (don't ask me why I know that!)
Get his A$$ back there to fix it, or get someone competent to do it right and send the first guy a bill.
yep yep yep
Thanks guys. I got a voicemail from the stone guy last night. He said there "must have been some dirt behind those stones" and that the "rest of them seem to be holding just fine". I looked at the bags in the garage and he's using TYPE M mix.
- Rob
I did some cultured stone on my house last year and put the wire mesh on first (personally I'd recommend it, I thought it was recommended but I guess that's just over the wooden section.) depending on how smooth the concrete wall is I wouldn't think you're not going to get a very good bond between the two (no matter what they say). You wouldn't pour one layer of concrete on top of another without a bonding agent.
As wormdrive said, you need to keep the existing cement moist to prevent it from robbing the mortar of water.
How long as the foundation been up? Is it a poured foundation or block? If it is poured, the form guy's use form oil to allow the forms to release easily on the breakdown. If you still have some form oil on there, that might be keeping the mortar from bonding.