Looking for advice from a MASON on fireplace stone

[Outer Rondacker]

Hi guys. As I have mentioned in other posts I am in the process of installing a Zero clearance wood stove in the house. I have built a chase inside my house 2 foot off the wall and 7 foot across the room. Going to the ceiling 22 foot in the air. I am getting ready to wrap the chase but, with what I do not know since I can not get a good solid answer from anyone in my area. I plan on putting up cultured stone around the fireplace to the ceiling.

My question to you is what should I wrap the chase with?

I have been told Durarock with the ruff side out. Then I was told half in plywood followed by Tyveck and expanded wire. Last I was told Durarock wrapped with expanded wire.

I just want the dang stone to stay and would like it to be as light as I can get it. If I could save a few bucks by not using Durarock and putting up plywood that would be nice since that stuff is 20 bucks a sheet here and a sheet is only 3x5. Wire is $22 a sheet and its only 2x8 in size.

If I put up Durarock what do I screw the wire too? I know we have fellas from all walks of life so I am calling on a stone layer / mason to give me some advice please. Thanks in advance as always Outer.

PS Advice on how to put up the stone would be great too as I have never done it.

[rancher1913]

mine is drywall, then durarock, then brick slabs about 1/2 inch thick. looks like real brick work and has lasted 20 plus years. inside is 3 layers of drywall, staggered joints because they did not have zero clearance back when i did it

[Outer Rondacker]

Thanks for the reply Rancher1913. Since its new construction and the air space is so large it only calls for none combustible 40 inches above the stove so I have used all wood construction with a few steel studs above the stove to the header for the small 38"x41" space. I will be putting Durarock over this spot no mater what. I am going to try and post a picture when I return home this afternoon. It might help.

[Rapier]

I owned a hardware store, sold wood burning stoves.

Before you get past the point of no return, do check
1) Local building Codes
2) Your insurance company for wood burner acceptability
3) Whom may install a wood burner in a residence, most, a cert from a licensed contractor

[Adam20]

i am building contractor, not a mason.
either way you described works, the mason installing it will have his preferred way.
Durarock and wire is my preferred way, it is available in 4x8 sheets also.
Wire is nailed to studs and scratch coat of mortar applied before cultured stone.

[Outer Rondacker]

I owned a hardware store, sold wood burning stoves.

Before you get past the point of no return, do check
1) Local building Codes
2) Your insurance company for wood burner acceptability
3) Whom may install a wood burner in a residence, most, a cert from a licensed contractor

Thank you Rapier,
1) They said no concreate pored then dont bother them. Seriously this is not the city we have very little in codes.
2)25 dollars for the year. They know I am installing it.
3) I am a licensed contractor in the area. I built the entire house solo.

i am building contractor, not a mason.
either way you described works, the mason installing it will have his preferred way.
Durarock and wire is my preferred way, it is available in 4x8 sheets also.
Wire is nailed to studs and scratch coat of mortar applied before cultured stone.

Thank you for responding Adam, I am not a mason either :} I think I am going to go with the Durarock and wire unless someone has a better reason not to on the site. I think this will provide the best stick but then again not a mason. The price comes out to be the same almost to the dollar as going with plywood and tyvek and wire. I am going to have to make a few calls to see if I can get my hands on 4x8 sheets as I think it will be a bit easier for me to do solo. Thanks for the advice.

[Shawlerbrook]

I also live in a very rural area in NYS and the fallback is the NYS building and fire codes. I agree on the Durarock and wire.

[ebb]

If you use durock you don't need wire lathe over it. If it were me it would be structural metal studs with durock screwed to them and stone attached with some of that really good thin set. There is a name for the good stuff but memory fails me right now. Zero clearance or not I would use nothing flammable in the whole thing.

[Misery-Whip]

Another contractor here...make sure to support the joists under this thing. We had to go back after another contractor to jack up a project like this. But we build 2 to 4 feet of crawl space here.

If your on a slab nevermind, sounds like a cool project! Please post a pic when its done.

[Outer Rondacker]

Another contractor here...make sure to support the joists under this thing. We had to go back after another contractor to jack up a project like this. But we build 2 to 4 feet of crawl space here.

If your on a slab nevermind, sounds like a cool project! Please post a pic when its done.

Thanks I will post a few pics soon. I have the stove itself sitting over triple microlams so that weight is ok. I decided to build a pantry under the chase the same size just for extra support of the weight of the stone.

[BLAHUT]

For my money, when I was doing this type of work, steel studs, durock, and the best thin set available now. Haven't done any of this type work for a few years, so don't know what is good stuff now.

[rancher1913]

i remember just reading the directions that came with the brick slices and used what they suggested for underlayment and glue/morter

[Woodtroll]

I did something very similar, over 20 years ago. Steel studs, durarock, artificial stone stuck with thinset mortar onto the board then grouted. Absolutely nothing combustible, which brings peace of mind when the stove or flue pipe gets too hot (usually because my wife has opened up the stove again!). Stone is still stuck to the board after literally thousands of heat cycles.

[Outer Rondacker]

Thanks for posting Woodtroll. The vendor I was going to use for the cultured stone said just thin set to the durarock but they also dont install anything so no real hands on experience. I like hearing imput like this. One thing is for sure. A all durarock chase is sure to keep a none combustible zone.

[ulav8r]

I did one years ago, used natural rock. Durock on studs, then a 1 inch airspace between the durock and stone. A few 1x2 air vents at the bottom and a small gap at the top. The rock was about an inch higher than the durock. Had a 1 inch airgap shield on back of the stove, 12-14 inch clearance between the stove and rock. The rock got warm but never hot.

[Bmi48219]

Don’t know about current codes but I’ve built many chimneys and fireplaces. Stone, cultured stone, brick, tile and concrete block.
Last one was for daughter and SIL, to code, cultured stone over Durarock & expanded metal.
If you put up mesh it has to be well fastened. When you plaster your putty coat of mortar over it you don’t want it to start flexing or sagging because your putty coat will slump off. Plaster’s lathe is the best, flat mesh needs to be stood-off with spacers so mortar can get all the way around the wires.
Don’t try to slick finish the putty coat, you want it to grip the bonding mortar on your stone. Wait until after the putty coat hardens to start stone work. You can get a little better adhesion by lightly dampening the dried plaster before laying stone on it. Type M mortar will work for plastering and bonding stone. Unless you’re blessed with a good eye for fit or you’re using rectangle shaped stone, you’ll want to test fit the stones before buttering them. You will want outside corner pieces if your work area has outside corners. Some cultured stone like drift stone can be trimmed a little to get tighter joints. Just remember the trimmed edge will be noticeable if it is too thick for grout to cover. The top edge of a stone above eye level can be trimmed with being noticeable as can the bottom edge of a stone below waist level.
The mark of good stone work is narrow mortar / grout joints. You don’t want to see a large area of grout between stones. For a novice I’d suggest one of the random rectangular cultured stones. If properly fitted you don’t even need to grout them. I dyed the plaster putty coat on daughter’s fireplace surround and dyed the bonding mortar so the joints between the stones were thin and looked grouted.
The mortar you use to adhere the stones should be soft and creamy. Trowel it on the back of stone firmly and as you set each stone press and wiggle it a bit to get a good bond to the wall. If mortar is too tight it won’t stick well so temper it with a little water to loosen it up.
Avoid getting mortar on the exposed side of stones. It will leave a stain or smear. They used to recommend starting from top of wall and working downward laying cultured stone so the mortar that squeezes out and drops doesn’t stain stones below. But then if the stones start slipping you’re in trouble.
Laying cultured stone is more like laying tile except tile joints are straight and consistent, stone joints are supposed to be random.

[Outer Rondacker]

Don’t know about current codes but I’ve built many chimneys and fireplaces. Stone, cultured stone, brick, tile and concrete block.
Last one was for daughter and SIL, to code, cultured stone over Durarock & expanded metal.
If you put up mesh it has to be well fastened. When you plaster your putty coat of mortar over it you don’t want it to start flexing or sagging because your putty coat will slump off. Plaster’s lathe is the best, flat mesh needs to be stood-off with spacers so mortar can get all the way around the wires.

Thanks Bmi, Perhaps my coffee has not kicked in yet it was a late night. So you put up Durarock then expanded wire before the cultured stone? Also are you saying you used Plaster as in dry way mix? You mentioned type M I was told by the lumberyard type S. Can you clarify or I will come back and read this again in another hour it might just be me.

Edit The wife and I like Large field stone look. So I guess triangle stuff. The stacked stone look we think would be to much 25 feet high. So larger we think is better. River rock is out as I think it looks like it should fall down being round stacked stone.

[Bmi48219]

The durarock was done by others. Personally I don’t see it being critical, 5/8 th drywall as long as it and the mesh are solidly attached to studs. Both the drywall and base (putty) coat plaster will be fire resistant and combined will be about 1 inch thick, providing a rigid solid surface. Important thing is you’re going up 25 feet. That’s a lot of weight, you want to make sure your studs, wall board and mesh are solidly attached. I’d lean toward studs on 12” centers myself.
Will your stove pipe go through the roof or out through the wall? That penetration is the biggest fire concern. Any masonry covering on a wall behind a modern wood stove will suffice to protect the wall from heat.
Type S is great for bonding, probably overkill but not a major additional expense. I don’t see where you’d need it for plastering the mesh but your choice. No drywall compound.
I’m not a fan of the ‘river rock’ look, it is too ‘busy’ looking and doesn’t lend itself to tight mortar joints. In the end you’re going to be looking at a large section of stone wall for a long time. Field stone is somewhat more angular so you can get it to fit together tighter. Cultured stone usually contains a lot of darker pieces that take some effort to position to be visually aesthetic. Your supplier should have reasonably sized sample panels on display. Examine them thoroughly; stone layout, joint size and how the stones fit together. The guy that laid that panel was probably a pro. You’ll want to try to duplicate his work.
You’ll have several ranges of stone sizes. Mix them so you don’t have similar sizes next to each other, same for colors. Remember you want your joint to be erratic and tight. The only straight joints should be at the top and bottom of your wall.
The stones come from molds, there will be a limited number of shapes and shades. It will be helpful to lay a bunch out on the floor so you can select one that fits the area you are working.
Take your time and step back once in awhile to see what your work looks like. If you don’t like how something looks change it. If you need to trim an edge for a better fit a you can use a crescent wrench to grip a thin edge and chip it off a little at a time. An angle grinder with a diamond wheel will work for straight cuts at top and bottom of your wall. You’ll have to hide the cut edge with mortar or grout if it is noticeable.
Ask the supplier if he’ll take back unused boxes of stone. You’ll want to have extra to start as some shapes will get used more than others.
Good luck.

[Bmi48219]

Thought of a couple other things.
Really no reason you can’t use plywood instead of DuraRock. As long as it’s solidly attached and doesn’t flex. If you were doing this wall outside you’d be using plywood. Forget the tyvex idea.
You’re a contractor so you know a scaffold is required. A 5’ x 7’ or 5 x 8 will give you room for your feet, a stock board and your mortar pan. Erect it so it’s 4” away from the plaster surface so falling mortar doesn’t bridge from scaffold foot board onto your finished stonework.
I’d put a layer of plastic on the floor and cover it with cardboard. Do all the lathe install first, then all the scratch coat plaster next. Rough up the surface of the plaster as you go (notched tile trowel or stiff brush) to get more surface area for bond mortar to grip.
Mix your mortar (for both plaster and bonding) in batches you can work before it sets up. You may find that for setting stone, letting the mortar sit a few minutes and re-tempering it will make it smoother and stickier. Use a spray bottle to slightly dampen a panel of plaster with water before you start setting stone. It will help with adhesion. Don’t let the water run down onto mortar below that hasn’t got hard, it will cause stains. You can lightly dampen the back of stones too. That will keep the mortar you trowel on the stone from drying out before you can press it onto the plaster. And don’t put 1/2” of mortar on the back of stone. A 1/4” will hold and not squeeze out / fall on the work below.
If you can set stone from top down without some pieces slipping and falling, you can keep your stone cleaner. If not try to protect yesterday’s work from falling mortar with tape and masking paper / plastic sheet. If you’re going to grout the stone think about dying the grout a few shades lighter or darker than the dominant stone color. It will help hide some of the staining.
Don’t get in a hurry, dry fit each stone before setting it. Remember, when you grout what looked like a thin joint between the stones will look a lot wider. Stone masons pride themselves on tight and, unlike tile, block or brick, erratic joints. Optimally you don’t want to see the corners of four stones adjacent to each other.

[GregLaROCHE]

Is Durarock what was once called rock wool?