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?

[BLAHUT]

Is Durarock what was once called rock wool?

I have only known it as cement board.

[Outer Rondacker]

Bmi48219 thank you for the great write up. Only reason I was considering 1/2 inch plywood was the weight factor and I would have a lot less waste. Easy to cut and less studs needed for the weird size.

Pipe is going straight up inside with a slight 30-30 zig to miss the microlams holding up the roof. Roof is true 12" of closed cell spray foam followed by 3/4 ply topped with metal.

GregLaROCHE Durarock is like hardy backer its concreate board held together with fiberglass webbing. Hope this helps describe it. So no its not rock wool.

[Bmi48219]

…Only reason I was considering 2 inch plywood was the weight factor and I would have a lot less waste. Easy to cut….

I’d go with plywood. There won’t be any heat behind it so fire safety isn’t an issue. As far as fastening lathe, it would be better than cement board / Durarock. Whatever you use the primary considerations are rigidity and retention of screws. Is the wall at right angles to floor joists? Twenty five feet of cultured stone and 3/4” of concrete plaster will be some weight on whatever is supporting it.

[Woodtroll]

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.

You're certainly welcome. One thing I meant to mention, but see someone already has, is to start at the top and work your way down. This works fine with artificial stone, which is made with air-entrained concrete full of little bubbles, so the artificial rock is significantly lighter than the real thing, and has a relatively flat but textured back that helps it stick to the mortar. I didn't have any problems getting the artificial stone to stick and hold, but the mortar consistency is pretty important and may take a little fiddling with to figure out. I think I used type S mix to stick the stone to the board, as it has a lot of Portland cement in it and is pretty sticky if you get the water content right. There may be something even better in use these days. As a contractor, you may already know about air-entrained concrete, and if so I mean no disrespect, but someone else following this may not know.

We used the large flat fieldstone too. My wife picked out the stones and helped with the layout as I "glued" them up. There were a surprisingly large variety of stone shapes and colors in the pallet I bought; I had expected little variation with only a few different shapes. The grouting was the most finicky part, as it's hard to strike or smooth the excess without it getting on the other stones. Our job turned out very nicely, if I do say so myself, and I had never tackled any stone work before, just some routine block laying and a little bit of brick work. I did have the advantage of working on different construction jobs that had some pretty fine masons at work, and getting to watch them work did help some.

I would not use plywood anywhere in this construction, given a choice.

Good luck with your project, and please do post photos when you're done!

[Woodtroll]

Concerning the decision between plywood and durarock/cement/Hardee board as a backer: Good dense plywood (not the 3-ply 7/16" crap they use for roof sheathing) is not significantly lighter than 1/2" durarock. You don't have to worry about high heat with durarock, and you don't have to try to affix wire mesh, which adds weight and is a chore in itself. Most importantly, durarock is dimensionally stable during temperature and humidity changes, at least as related to other masonry. Plywood will shrink and expand with humidity changes, and my few trips canoeing the Adirondack lakes lead me to believe that the Adirondacks are a lot like Virginia in that it's humid as heck in the summer, and much drier in the cold winter weather. Add heat from a woodstove to the dry air, and that plywood is going to move quite a bit from moisture content changes, and it would worry me that it might move enough to pop some of the mortar loose eventually.

Just my two cents' worth, even less valuable now due to inflation! Good luck!

[GregLaROCHE]

I thought I would share what I learned about building a stone chimney. If you use lime instead of modern cement, The mortar will withstand much higher temperatures than normal cement. You can buy special refractory cement, but it’s a lot more expensive.

[Plate plinker]

I have done a fair bit and will tell you BMI is setting you down the right path. The only thing I might do different is I use a notch trowel to make a key way in my scratch coat. Been told it’s not necessary but so what you have to trowel the scratch coat anyway! Might as well go above and beyond the lazy people. To fasten wire mesh I use screws that don’t rust and put a small washer on them to grab a bit of the mesh. Kept it tight and not floppy. Take your time and KEEP everything clean. NO mortar on your fingers.
Whatever panel material that is not masonry should have roofing felt or tyvek on it. It’s cheap and easy to apply and is more insurance of overbuilding in my opinion. Why risk having to redo the work?

[Bmi48219]

I thought I would share what I learned about building a stone chimney. If you use lime instead of modern cement, The mortar will withstand much higher temperatures than normal cement. You can buy special refractory cement, but it’s a lot more expensive.

Most refractory cement doesn’t achieve bond strength until it is cured at high (1200F plus) temperatures for days. It is great for laying a firebrick lining inside a firebox or chimney but you don’t want to expose it to water. Water and refractories don’t play well together.
In simple terms all refractories (mortar, castable and gunite) are bonded with one of a variety of high purity alumnite cements, not too different from calcined limestone used in Portland cement. The particular alumnite cement used is selected based on the expected temperature the product will experience along with the atmosphere and the environment the refractory is designed to contain.
Portland is good up to 450F. In the majority (99%) of any type of cementitious mix the bulk of the product (and it wearability, tensile strength and refractory qualities) are results of the type of aggregate minerals (sand, stone, alumina, zirconia, spinel, etc) the cement binds together.
Back in the old pioneer days it was common practice to mix cow manure in with the sand & cement mortar when building a stone or brick chimney. The resultant mortar was capable of maintaining bond strength at temperatures that would cause regular mortar to fail. That is why bits of straw are often found in the mortar when pre-20th century chimneys are torn down.

[Outer Rondacker]

You guys are making me feel better about this project. I set the stove in place yesterday. 560 pounds on a 6 inch high dolly needing to jump into a 12 inch high firebox. Its always fun working alone. A floor jack and some blocking followed by a come-a-long hooked to the header made it light work. Then cutting the whole in the base for the fresh air intake was a challenge of its own due to lack of space for tools but its done and the pipe is hooked up. Still need to punch the hole to the outside. Today I head for materials for next weeks work. The next goal is to finish the closet in the basement that will provide some basic support and get the electric, cable and ethernet wires run to the chase. Oh and put the superstrut up to hold the tv mount above the stove.

[Bmi48219]

O.R.,
from the activities you related in post #29 it’s sounding more like you’re install a zero clearance fireplace unit than the ‘stove’ mentioned in post #1. It won’t make much difference as far as the stone veneer goes. As previously mentioned your looking at approximately 230 square feet of cultured stone. At 20 some lbs per sq foot installed (stone, mesh and mortar) you’re looking at roughly 4,600 lbs masonry or 210 lbs per lineal foot of floor-to-ceiling masonry, plus the weight of the fireplace / stove / stack, studs and plywood. Most of which weight will be bearing on whatever supports your floor, a couple feet in from your foundation. You’ve probably already considered this. Your floor has a live and dead load rating. Some under joist support may be advisable.

It sounds like your exhaust gas stack will be enclosed by the framing that supports the stonework. NBD, just follow your unit’s install instructions and make sure the stack-to-firebox joint is sealed. They are designed to be safe for this installation.
Again, take your time and good luck.

[Outer Rondacker]

Yes zero clearance stove. Osburn Stratford II with double wall insulated Selkirk chimney. I have triple 14" microlams running under the stove. I made a pantry/ closet under the entire section in the basement out of 2x6 studs sitting on 6" concreate floor. I even blocked the build. 10" foundation will be supporting a small amount of the weight as well.

This is why I was wondering why I had to durarock the entire 14 square foot chase since the only none combustible spot is just over the stove. Sure would be easier to put up some 5 layer plywood. More ridged too I think.

Ever since we got cellphones I have not used the digital camera. I have no way to post a picture until I find that dang camera. I know is in this gun room someplace. Pics to come I hope.

[Bmi48219]

This one?

https://cdn.shopify.com/s/files/1/0100/7917/4734/products/stratford-ii-wood-fireplace-with-heat-activated-variable-speed-blower-osburn-stratford-ii-wood-fireplace-with-heat-activated-variable-speed-blower-ob04007-33431027253418_2048x.jpg?v=1648538354

[super6]

Well, My dad was a Mason, He built 5 story fire places with multiple openings, He would NOT put one up with out at least a 4' concrete butt to carry the load, Ya just have to think all of this out. I built my home from scratch and put a butt in for a future fire place. As far as the chimney, Flue liners + a 4" dobie casing and back filled with type s mortar. And you will need a fresh air source other than your interior. Hope this helps! In S.C. it will not pass inspection without the outdoor air induction

[Bmi48219]

The OP noted early on he was cutting a penetration through the outside wall for combustion air. His zero clearance exhaust pipe is already double insulated, and if manufactured and installed per specs, just as good as the old clay flue liners, while being considerably lighter and less prone to cracking.
Using refractory mortar to seal the joints between clay flue liners is sound practice as was ‘kicking’ each liner with brick bats to arrest lateral movement. Clay liners expand when heated and contract when cooled. Wrapping the flue liners with ceramic fiber blanket was best practice in terms of fire protection and allowing the clay liner to expand without pressing against the kickers to the point of cracking themselves or the masonry chimney.
Forty years ago in Michigan someone started a company that “repaired” crack flue liners by pumping light weight refractory concrete to seal around the flue. I made a lot of money rebuilding chimneys they had fixed. At least in northern climates with frequent freeze-thaw cycling, solidly encasing clay flues isn’t a good idea.

As and aside:
My dad related to me he was often privately hired to build fireplaces, sometimes by people he wasn’t sure would pay. His practice when in doubt was to put a thin pane of glass in, blocking smoke from escaping through the flue. If the owner looked up the chimney the clear glass wouldn’t be noticeable. After receiving payment dad would place a bucket in the fireplace and swing a brick tied with line down the flue breaking the glass to fall into the bucket. If he didn’t get paid he left the glass. The customer usually wound up paying later.

[Outer Rondacker]

This one?

https://cdn.shopify.com/s/files/1/0100/7917/4734/products/stratford-ii-wood-fireplace-with-heat-activated-variable-speed-blower-osburn-stratford-ii-wood-fireplace-with-heat-activated-variable-speed-blower-ob04007-33431027253418_2048x.jpg?v=1648538354
Yes sir that is the one. I would of rather had a rounded top than the square look but I got a really good deal and I could use the new pipe I stumbled across for next to nothing.




As and aside:
My dad related to me he was often privately hired to build fireplaces, sometimes by people he wasn’t sure would pay. His practice when in doubt was to put a thin pane of glass in, blocking smoke from escaping through the flue. If the owner looked up the chimney the clear glass wouldn’t be noticeable. After receiving payment dad would place a bucket in the fireplace and swing a brick tied with line down the flue breaking the glass to fall into the bucket. If he didn’t get paid he left the glass. The customer usually wound up paying later.

Love hearing things like that. If he tried it now I bet he would end up in a hole lot of trouble even if they didnt pay. Ah the good old days.

[Outer Rondacker]

310533

Here goes nothing. The chase is 25" off the house wall to land on the floor joist. Its will be 7 foot wide once half inch of sheathing is added. Still dont know what I am going to line it with. I just know its getting durarock up to the header on the front side no mater what. The unistrut is installed over the stove to hand the 75" tv from once its up.

310534

I have to finish the chase to the roof just have not got that far. Looking for a buddy to hand me stuff once I am on a ladder. Plan on putting down a sup floor as a fire brake I think before I frame the rest of the wall up top, not sure still need to figure it out.

310535

Back side of the area the TV mount will be attached too.

310536

Fresh air intake needs to be piped outside. Something is telling me I screwed up adding the pictures. I will see. Oh I should add the 2x12 box will be built in front of the stove area after I remove the wood floor to support the hearth I plan on making from concreate this summer. Board is sitting in front to give the wife an idea of the hearth height. Think its going to be a 14" box with a 18" stone hearth so after I add the board and stone I will get a 2" overhang. Enough already lets see if these pictures took.

[farmbif]

I only use wood to heat and anything and everything electric or electronic is far away from the wood stove. when the stove gets real hot on the coldest days any firewood within an inch or so can get charred. those 2x4's on the side and below look awful close.
I will add that I burn a lot of different kinds of hardwoods and some times in trying to get the place warmed I put in too much or something that happens to burn real hot and its gets really hot. excessively hot. and another thing you may encounter is when you first start using a new wood stove it might smoke all of the paint and finish off and fill the house with burned paint fumes, thats what happened with the new stove I got several years ago. if I ever get a another new stove it will be fired up out in the yard first before coming inside.

[Outer Rondacker]

I used to start my stoves in the yard first. This one is a slight bit different, but I think it will be ok. The 2x6s are within specs for a zero clearance. I have only ever heated with wood until I build this house six years ago. This is more for end of days and power outages. Or at least I am telling myself that. My current heat bill is $600-750 a winter. Not too bad for close to the Canadian border.

[Bmi48219]

Here goes nothing. The chase is 25" off the house wall to land on the floor joist. Its will be 7 foot wide once half inch of sheathing is added. Still dont know what I am going to line it with. I just know its getting durarock up to the header on the front side no mater what. The unistrut is installed over the stove to hand the 75" tv from once its up.

I have to finish the chase to the roof just have not got that far. Looking for a buddy to hand me stuff once I am on a ladder. Plan on putting down a sup floor as a fire brake I think before I frame the rest of the wall up top, not sure still need to figure it out.

Back side of the area the TV mount will be attached too.

Fresh air intake needs to be piped outside. Something is telling me I screwed up adding the pictures. I will see. Oh I should add the 2x12 box will be built in front of the stove area after I remove the wood floor to support the hearth I plan on making from concreate this summer. Board is sitting in front to give the wife an idea of the hearth height. Think its going to be a 14" box with a 18" stone hearth so after I add the board and stone I will get a 2" overhang. Enough already lets see if these pictures took.

You’re putting Durarock on the face wall around & over fireplace? What on the rest of the to-be-covered-with-stone surfaces? You’re planning on putting a subfloor below the unit in lieu of the wood flooring? If it’s going to be difficult to fit a wood subfloor and you don’t feel like pulling out the fireplace why not a piece of mesh and one inch for mortar?

I’m guessing you are already living there. Did you pull a permit on the fireplace install? If so the building department could tell you their expectations, like whether you have to cover the inside walls of chase and with what. Or minimum dimensions of your raised hearth. A non-permit fireplace is a good excuse for your HO insurance company to deny a claim.
Your wing walls span over to a joist, did you beef up that joist? Ditto for whatever bears the weight of the raised hearth.
I’m not following the concrete hearth idea. If the box for your hearth is solidly built you could cap it with a piece of 3/4” plywood or 1-by boards and lay the stone cap in thin set directly on that. I’d bring the stone up to top of your hearth box, you can trim any stone that is too high because the hearth stone overhang will hide the cut. Figure how thick your hearth stone and setting bed will be and temporarily set a piece of wood that thick and the OA length of the hearth in its place. Put some tape on the top of wood for a parting joint and lay the fireplace facing stone on the wood. When you are ready to set the hearth stones pull the wood to give you a chase for your stone to slide into. I’d set those hearth stones after you’re done with the cultured stonework so they don’t get cracked or mortar stained.

That’s a pretty floor, cover it well. You’ll need some place to layout stones for selection too.
A ladder might work for topping out the chase walls but do yourself a favor and use a scaffold for the masonry install.
You’ll have to make some cuts. If you don’t have a tile or bricksaw an angle grinder and a 4” diamond wheel works well.

The way I see it a zero clearance fireplace, properly installed, is designed to seal the products of combustion (Fire, heat and smoke) in where they can’t cause harm. The installation instructions should specify what, if any, grade of owner supplied materials are needed to line the fireplace surround. I guess you could line the chase inner surfaces with drywall but you shouldn’t have to IMO. That’s why you bought a zero clearance unit. Whether you line the chase or not if a fire starts the entire chase will become a flue.

[Outer Rondacker]

BMI, The current chase is 10' off the floor. I need to take the sides to 18 ish feet to meet the walls. I was thinking of putting a piece of sub floor on top of the chase before finishing the walls. Gives me a place to stand. After I get the chase walls finished being framed I would just cut a 16"x16" whole in the plywood to allow the chimney to pass. This is not needed just might help me reach the dang top since its so high.

The stove calls for non-combustible up to the header over the stove. That is why I used some metal. It also calls for it on two inches of the face sides. So no mater what I have to put durarock on these places. Durarock is weak and if I was going to still put wire up I would rather cover the rest of the chase with plywood but if I didnt need wire durarock would get it done in one pass.

I have to cut up the 3/4" hardwood hickory floor before building the hearth box. Once the box is built I will be putting down a concreate created hearth or bluestone if I can get it reasonably. I had planned on doing this last. Was going to make it 20" off the face of the stove. More than meets any codes. For height code states more about what is under it than how high it is. Since its elevated I would be more than ok with 2 inches stone or concreate.

As for holding up the entire structure I have that more than covered.

I have no plans on putting anything inside the chase like sheetrock or wood. I only plan on doing what ever is needed outside to hold the stone.

[Ed K]

Great thread. Not a mason but have done quite a bit of tile work. BMI has done very well for you with his pointers. My preference (strong) is for Durock over Hardie board. Hardie board tends to be quite thirsty which I believe is due to having cellulose in the mix and could dry your scratch coat too quickly possibly sacrificing some bond strength. Have witnessed thinset not properly adhering due to this. Yes, Durock sucks to cut but on any job of size we just set up a couple of sawhorses over a tarp and with a hand-held tile saw with diamond blade go to town.

[white eagle]

laid miles of the stuff
we used tar paper as a vapor barrier, sort of like your tyvek
then the wire then a scratch coat of mortar and finally the stone
be sure to apply a good amount of mortar on each stone for a good stick
then finish the joints on however you like them
we always raked them and brushed them
good luck was a mason for 25 years

[Outer Rondacker]

Wish one of you guys where local I would give you a job. Got the electric and fresh air intake done today. Also the channel for the cable, ethernet wires run. (almost)I wasted a day gun shopping but I am in no rush. A few days ago I tried to order stone and got laughed out the lumber yard. They said I had better chance making it myself. I guess they are backordered over a year. Honestly that is the last thing on my mind. I will keep plugging away and add an updated picture soon.

[Outer Rondacker]

Project got put on hold yesterday afternoon. I was finishing up screwing the pipe for the fresh air intake together and going to duct seal it when I slipped off the ladder and grabbed the pipe thus braking it and exposing's a very sharp part. Yeppers cut my hand pretty good. So taking a few days off to heal up. Nothing some super glue and duct tape didnt fix up. Worst part is now I have to rework the pipe back to the first floor from the basement again. It was not fun the first time doing it solo.

[Bmi48219]

…we used tar paper as a vapor barrier, sort of like your tyvek….

When I started laying brick tar paper was the only vapor barrier.

[Bmi48219]

OR, did you get your stone ordered?
We took granddaughter out to Cracker Barrel for breakfast yesterday. While gagging on the worst sausage gravy I’ve ever had I noticed their stone veneered fireplace. I took a couple pictures so you can get a idea how not to layout your stone.
I can’t get the pictures rotated but being 90 degrees off doesn’t make them look any worse. The near straight, stacked mortar joints in the top picture is what you want to avoid.
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[Bmi48219]

I visited my BIL Tuesday. Almost forty years ago he was converting a garage into an ‘up north’ cabin. Here’s some pictures of the cultured stone fireplace and chimney I veneered for him. This was actually one of my first cultured stone jobs. Took three months working a couple days a month. I got the mortar joints pretty tight but had less success staggering the bed joints. Dyed the mortar joints on the inside work cause I didn’t like the way the chimney joints looked outside.
Don’t recall who made the stone but we picked up a trailer load of it in Wixom, Michigan. The style was called ‘California Drift’.
The cabin is near Traverse City so it sees a lot of snow and cold. I checked it over closely, not a lose stone or crack to be found.
Sorry about the pics orientation.

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