Did you just scratch over the top of cement board?

I would suggest tearing everything out and screw lath over the top...usage of cement board does not provide mechanical bond.

 

The manufacturer had suggested one of two methods - metal lathe over the sheetrock with a moisture barrier or scratch coat over cement backer board. I tore out the sheetrock and went with cement board screwed to the studs.
It was suggested by someone else i should have dampened the board to assist the scratch coat in adhereing?

 

You should have dampened board just a little with wet sponge(not dripping,just wet) to prevent it sucking out liquid out of the mortar in scratch.

As given,let me tell you something,if someone else gave you specifications then why ask us?

If you going to argue point I made then might as well just do what they told you. As it turned out now your scratch is peeling,thankfully before you installed anything.

I told you my suggestions...there are a lot of things I would have done differently..whether I was scratching rght off top of board or lathing it.

Good luck.

 

Why not lath over what you have now?

 

He might not be able to properly attach it and scratch he has right now is probably not sound so over time it might fail the lath even if he uses long enough screws.

 

Problem is that I scratch coated two weeks ago and started buttering the stones and sticking them to the wall last week!
Now that I have just reached 6' high I realized that some of the area at and above that heigth is not adhered to the cement board in two basketball sized pieces. Those pieces peeled easily off the wall but the rest all seems to be quite stuck to the cement board.
At this point to tear it all off and start over would be quite a project.

 

I recently did 1200 sq ft of veneer over cement board...specifications call for scratch coat and then mortar bed over cement board.

I just went with cement board,then lath,then scratch,then stone.

Cement board is not always made out of cement,there are plenty other filler materials that go into it.

Essential use of cement board is to protect from water damage since no masonry wall(whether stone or brick) is 100% waterproof. So cement board gives you extra piece of mind.

No it wont be that hard to take it off,just use proper chisel and dig into the joint.

Otherwise you wont be able to judge how well it adhered until it may fully come down...

 

I never trust cement board to hold. I like the mechanical bond that the lath gives. I can see that it will hold rather than just trusting manufacturers who say it will. Same with concrete. If it's too smooth and fresh I will use an acrylic additive whereas with the diamond lath I see no point.

For the areas that have seperated i would take a chisel to the edges of what hasn't to make sure it isn't coming off and then re-parge with a type S with a good splash of additive. As for the stuff you've already done...cross your fingers i guess and make sure your liability ins is paid up for a few years

 

I never trust cement board to hold. I like the mechanical bond that the lath gives. I can see that it will hold rather than just trusting manufacturers who say it will. Same with concrete. If it's too smooth and fresh I will use an acrylic additive whereas with the diamond lath I see no point.

Fully agree..

What if you had a stucco surface to lay stone on?

You still screw it in? I Used to do that for longest time...

Now I just check what paint is on(if any) if none I just weld-crete it and skim scratch over the top.

if painted,I rough the surface with grinder before weld-creting the area.

 

well you can always tell how deep the substrate is by just jamming a long nail in. I personally haven't seen any foam more than 1", unless there's a band course or trim around windows etc.. It would make me nervous tho that the screw or nail wasn't sunk. I don't really trust cultured stone period, let alone some lath that's 1" away from the substrate. But at that point I'd deffer to the contractor and put the liability on him

 

yea they got all sizes of STO foam around here,last one they brought in everyone is crazy over...(5")...:blink:

Hydro offers rebates so people get the beefiest stuff they can...

 

a few years ago I was on a job and one of the stucco guys had recently moved from Winnepeg. He hadn't touched acrylic until he moved to Ottawa, always done masonry stucco before. i haven't seen masonry stucco in over a decade.

 

Thats sad really...I think masonry stucco is way better looking.

 

I have pounds of EIFS on my clothes, I am convinced that the stuff has some serious lasting power after all the washings its held up through.

But like The Italian said, you have to have a moisture management system with it. The stuff was designed to go over steel studded commercial buildings, it leads to trouble with wood framing. Traditional stucco though works well in that situation.

 

I have pounds of EIFS on my clothes, I am convinced that the stuff has some serious lasting power after all the washings its held up through.

.

That is true,but its a contraversial topic...I have seen holes in acrylic from where it was knocked with foot or a soccer ball etc...

but properly done acrylic or sand/cement will give you same effect.

With sand/cement stucco you have to watch more things compared to acrylic.

With acrylic you need proper moisture management. Now that is sometimes PITA to sell to customer...

 

No scratchcoat over board, thinset directly to it for adhered veneer.

 

I could see thinset sticking better to cement board since it seems to use a chemical bond rather than a mechanical bond (I don't really do tile so I'm just guessing here) but for a product like cultured stone, where there is such a rough back, would there be enough surface contact to make a decent bond to the unit?

 

I have done maybe 6 stones total with thinset(ran out of mortar,didnt wanna drive to vendor,had bag of thin sitting in van) and I gotta say I hate it...thinset has peanut butter consistency,its hard to handle compared to simple mortar...I can see how what Tscar is saying is plausible but I still wouldnt want to do it because of thinset's consistency.

Not to mention that you still getting reg. mortar anyway because you gonna be grouting if you are wet-stacking.

 

Quit buying cheap ass Home Depot thinset. The good stuff has a 45 minute board life in the heat, is high-build and highly modified, and you even have time to adjust the stone before it grabs.

 

Quit buying cheap ass Home Depot thinset. .

Who told you I am buying HD thinset?

 

what about the lack of surface area on the back of cultured stone, eldorado stone etc.. i can def see using it on "realstone system" or any natural stone with a saw cut back but the rough back of culutured stone, there's less against the wall than not

 

Follow manufacturers installation instructions for the thinset, not the stone, since they warrant the bond.

 

Interesting. Square notch or V notch?

 

Margin, since they require full coat on the stone, not the board.

 

What, just glop it on? or a thin smear over everything?

I've used PL many times before for fireplaces, I could climb the wall the next day, but never thinset.

 

http://www.laticrete.com/dealers/products/anti-fracture_crack_supression/productid/54.aspx

 

oh, I see. extra steps required and about the same result as a mortar with acrylic additive. That installer has no idea bout masonry, that's obvious.

I think i'll keep staying away from thin veneer except for fireplaces.

 

you dont do any cultured besides fireplaces?how come?

 

actually the stuff was invented to repair masonry buildings damaged in ww2

 

I do, but i try to price them not to get them. I don't like it and I don't trust it. I don't like that I can't cut it without having to hide the cut. I do fireplaces because they're quick and good indoor winter work or weekend jobs

 

If you talking about quality of product,then yes I dont trust them.

But I find it to be quick cash...it is great way to do some winter work though I agree...

 

Do the kind of work you want to do, but if you are going to do it, do it right. Lath over cement board is stupid, as is scratching board. If you are going to stick concrete to concrete board, then do it with a product engineered for that purpose.

 

Lath over cement board is stupid, as is scratching board.

If you have to paint 2 coats of that primer on, why not attach latch and scratch coat? I still trust the mechanical bond

 

Just for the record, I am using real stone that has been veneer cut. Product put out by Quarry Cut. Much better feel and appearance than cultured. Very smooth backs from the diamond blade saw that cut them.

Building a dry stack wall but we may have to grout in between some spaces that I can not get a real tight fit with the stones.

The manufacturer and vendor recommended S mortar for the scratch coat and to stick them up.

 

The manufacturer and vendor recommended S mortar for the scratch coat and to stick them up.

thats fine,so manufacturer recomends sticking the stone straight onto cement board?(without lath)

 

Apply mortar coat to cement board. After that dries butter stones to the wall.

 

Lemonbomber, does the manufacturer warranty the bond of the units to the base?

 

Do you mean the bonding of the stones to the board?
I never thought to ask about a warranty.
Yes, this is my first foray into this field and I am learning alot on the fly.

 

If laticrete warranties the bond then that's pretty good. There is a product at Home depot around here that is a mortar specifically for laying up thin veneer. Never looked at the specs or warranty since it's almost $20/bag (much less I'm sure in US). Maybe worth looking into also.

 

If laticrete warranties the bond then that's pretty good. There is a product at Home depot around here that is a mortar specifically for laying up thin veneer. Never looked at the specs or warranty since it's almost $20/bag .

as in thinset or reg mortar?

 

I'm surprised the thin veneer supplier recommends tile backer as a suitable backer. Sure, it will work with an expensive thinset, but lath is far easier IMO. Just need to plaster the day before with Type S and a v-notch trowel, and add a small amount of bonding agent to the bedding mortar. As for what to do now? Not sure to be honest, as I take it you laid the joints in with the stone right away, and some of the stone is still loose??

 

I think only the scratch coat has come loose, no loose stone yet. But that was yesterday, today is a new day.

It's raining rocks, Hallelujah, it's raining rocks.