Stone Veneer Pillars

chan58

Hi all -

I'm a complete rookie with masonry. Of course, that's never stopped me from jumping right in. I'm building a fence that consists of four stone pillars and three cedar panels. The 6' (above grade) pillars are made from CMUs, to be covered with a field stone veneer. I have a couple of questions:

1 - do I have to scratch-coat the CMUs before I can attach the field stone?
2 - assuming the answer to (1) is YES, then is it necessary to "rough up" the mortar after applying?
3 - again assuming the answer to (1) is YES, what kind of mortar would you recommend for the scratch coat? I'll be using Type S to set the stone.

Thanks...

artisanstone

First of all, what is your veneer thickness? Stone is laid as either thin (1-1.5") or thick (5-7") veneer. Thick veneer needs steel ties. Thin veneer needs a scratch coat of Type S, but you need to apply bonding agent to the block first.

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Tommy C

No need to scratchcoat the block.

chan58

I'm sure this makes sense somehow, but now I'm confused - scratch, or not?

Quote:

Originally Posted by artisanstone what is your veneer thickness? Stone is laid as either thin (1-1.5") or thick (5-7") veneer.

I guess I'm in between - its not mastercut (I bought my stone at Luck), but real field stone. I'd say it averages 2" per stone - some thinner, some thicker. Jaysus, since the pillars are already built, I hope I don't need steel ties for this stuff. I'd have to go buy mastercut or something if that's the case.

Tscarborough

Anything less than 3" should be considered to be an adhered veneer, and as such does not require ties to the backup. If the stone is very dense, like a granite or slate, you should probably use thinset, otherwise type S with bonding agent is fine.

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tkle

Common cement. #/1 mix with a pinc3 of lime to keep it from bleeding. No scratch coat. Parge the wall and the back of the stone as you go.

chan58

Ok, thanks - this helps. I've got one cement, one thinset and two type S's - think I'll go with Type S (bonding agent), no scratch coat. Parge block and stone.

Another, unrelated question. I made a form for the caps, and plan to cast them myself (since I'm retired, I try to save where I can). The form is made of pine stock for the sides, and plywood for the dome. Its a standard 24x24 pyramid, 3.5 inches of straight side, then pyramids up 3 inches to a crown (sort of like a mansard roof, no curvature). I planned to cast with fiber-reinforced concrete, colored for aesthetic. My question is what, if anything, should I use to coat the inside of the form to get the concrete to release so that I can reuse the form? (I'd post a pic, but the site won't allow it).

I really appreciate the input...

CJKarl

They sell form release stuff, but for a small project like yours I would just carefully spray it diesel. (shhh, I didn't say that)

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chan58

Thanks - I'd already lined the form with plastic membrane for a test run. If that doesn't work well, I'll try this.

Hey thanks everyone for the help...

stacker

i have made a few caps in the last few years.i think you are going to find the plastic is going to give it a fake plastic look.
we have always used sheet metal and 2x4 or 2x6 depending on how big we wanted them.the sheet metal was put in a break and given a slight pyramid look.
when we were ready to pour we made sure they were on a level surface and sprayed the inside form with diesel or kerosene.
make sure you shake the form or tap it with a hammer while pouring or you will have honeycombs.

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chan58

I had the same suspicion about the plastic - we'll see what happens when I pop the form later today.

Sheet metal - interesting. Never bent a pyramid before, but I'm fairly handy with the brake. I may try that.

Either way, sounds like diesel is the way to go. Thanks again...

chan58

Hey, whatdya know - I have a nice plastic-looking pyramid cap to place on top of my pillars.

Actually, it doesn't look all that bad once it's up. You can't actually see the tops anyway. But one thing I noticed is that, at 24x24, they're too big. I figured a 2" overhang on a 20x20 pillar would be about right, but it ended up looking like a skinny rice-paddy worker. I'll have to adjust the mold back - I don't know why I thought it had to overhang. Maybe if I molded some sort of cornice it would work, but as a straight cap I'm guessing it should just be close to flush.

stacker

we either lay it flush or about 1/2in overhang.i like the 1/2 in better than flush personally.

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CJKarl

I usually go with a 3/4" overhang. Another way to finish it would be to pour it in the morning and keep an eye one it. When it's strong enough to support it's own weight, strip it and rub it with a damp sponge float while it's still green.

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Tommy C

What's wrong with Type N mortar for thin veneer?

Tscarborough

You are allowing yourself a very thin margin of error. Freeze-thaw just narrows the margin further.

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chan58

Great suggestion popping the mold while still green and sponge floating. It smoothed out all the surface pits and then enabled me to scrape all the rough edges down smooth. I think I popped it a little too early (8 hours), because some of the side edges crumbled. Oh well, I can live with a little "character" at $10 per cap...

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LNG24

Post some pics when its on the pillars. I might do this on mine until I can afford bluestone caps

chan58

Unable to find any more excuses, I had to start putting up stone today. Jaysus, how naive I was to think that years of designing and laying tile might have prepared me to work with natural stone. There is a reason masons are called "artisans". What the hell was I thinking? Not only was it difficult to work the stone quickly enough (finding the right stone, chipping it - holy crap rock is hard), but getting it to actually stick to the block was a challenge. I thought I'd get some suction, but it just kind of sat there for a minute then fell away. It took numerous tries to get something to stay put. I finally decided that it was best to work one or two layers then move on - going too high was a recipe for disaster.

On a lighter note, I ran into a stone contractor at the stone yard today while getting a bed full of sand. I gave him my number and told him to call me if he ever needed free labor. Given how much stone work I'd like to do around my property, I guess helping a real mason is what it'll take to get good at this...

Tscarborough

Lay out about a square foot of your rock. Weigh it and if it is more than 10-12 #'s per square foot, you are laying the stone, not sticking it.

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