New hearth for the Princess

[Highbeam]

About 8 years ago I tore out a masonry chimney, fireplace, and Lopi insert to install a Hearthstone Heritage. It was a good move, the masonry was of questionable quality and was over 45 years old. The heritage had some crazy hearth requirements and needed a high R-value so I used metal 2x4 studs and 2 layers of durock, no wood, and tile all over it. The hearth was low at about 5" above the subfloor and wide to accommodate the side loading door clearance requirements.

Then, after about 30 cords, I drank the koolaid and switched to a catalytic blaze king which was barely legal on the hearth with regards to depth since it was a much deeper stove. Also, the OAK connection was off to one side and very visible and a bit ugly. It was all 3" semi rigid and was routed within the hearth since the old chimney footing prevented a vertical drop into the crawlspace.

Getting ready to replace my flooring I decided now was the time to rebuild the hearth to reduce the width, increase the depth a bit, center the OAK stub, raise the hearth more, and make it look better.

Tearing the old one out was a PITA. When I set the steel framework I attached it to the floor with a lot of screws. Then attached all the durock and tile. It was very heavy, big, and overbuilt. How the heck could I access those internal screws? I couldn't. I chipped off the tile and then used a big steel digging bar to rip the screws out. Lesson learned, attach the new hearth in such a way that it can be removed from the outside.

I chose 2x8 lumber for framing. Joists 12" on center plus one under each end of the stove so that support is excellent. This will be topped with 3/4" plywood and then those 2" thick cultured hearthstones. The BK requires only spark protection and the hearthstones with grouted joints 1/2" or smaller are UL approved for this application. Finish height should be 10" to top of hearth.

Here's my progress so far. I'll follow up as I build.

 

[BKVP]

Got to love the kids Highbeam. Those girls around 12 years old now?

 

[webby3650]

This is one of my favorite Blaze King/kid pics.

 

[Highbeam]

Got to love the kids Highbeam. Those girls around 12 years old now?

Yes, the big one on the left will be 13 this winter. They both helped with the wood processing this year. The girls think thnew hearth will be too tall.

 

[Warm_in_NH]

Don't see any problems setting the stove on top of cultured stones? Or do you have a plan for where the legs land?
I ask because most of the cultured stone products I've seen are rather light weight and break easily when stressed.
Trying to decide of a finish for under the Oslo, but without going with real stone (gonna be heavy on an already old floor system), I figured tile was the only option.

 

[webby3650]

Yes, the big one on the left will be 13 this winter. They both helped with the wood processing this year. The girls think thnew hearth will be too tall.

I think it'll be a very nice addition! I wish I would have made a raised hearth in the family room with the Ashford. It's nice for viewing the fire and makes It nicer to load the stove. I think it's a good call.

 

[Highbeam]

I think it'll be a very nice addition! I wish I would have made a raised hearth in the family room with the Ashford. It's nice for viewing the fire and makes It nicer to load the stove. I think it's a good call.

Problem is I just lost 4" of chimney height. @BKVP will kill me! Another set of new holes to be drilled into the double wall for probe meter and screws.

I did upsize my OAK plumbing to 4" diameter since the 3" just seemed small and in rigid duct there is not much 3" to be had.

 

[BKVP]

Problem is I just lost 4" of chimney height. @BKVP will kill me! Another set of new holes to be drilled into the double wall for probe meter and screws.

I did upsize my OAK plumbing to 4" diameter since the 3" just seemed small and in rigid duct there is not much 3" to be had.

You shortened your chimney?!!

 

[BKVP]

Actually I had to respond now that you egged me on...Of my two boys, only one enjoyed the wood gathering. The other one is smarter than his old man.

 

[Hogwildz]

Be careful with the cultured stone. It is merely cement with paint on the surface. Any scratching or chipping and concrete will be showing. Might be better to consider real stone for the surface material.

 

[Highbeam]

Be careful with the cultured stone. It is merely cement with paint on the surface. Any scratching or chipping and concrete will be showing. Might be better to consider real stone for the surface material.

So the hearthstones I bought are "charcoal" dyed concrete. Poured into rock looking 20x20" forms. There was damage to one and the color goes all the way through which is good. Unfortunately, the inside of the stones do look like coarse concrete texture and not what chipped stone would look like. I've used tile before that was very dark on the outside but the inside was bright terra cotta orange so that any chip would be very visible, that is way worse.

 

[quotejso]

Yea I used the el cheapo slate stone from Home Depot after sorting through many boxes I found some good pieces.

 

[Hogwildz]

So the hearthstones I bought are "charcoal" dyed concrete. Poured into rock looking 20x20" forms. There was damage to one and the color goes all the way through which is good. Unfortunately, the inside of the stones do look like coarse concrete texture and not what chipped stone would look like. I've used tile before that was very dark on the outside but the inside was bright terra cotta orange so that any chip would be very visible, that is way worse.

Well at least the color runs through. I used true Owens "Cultured Stone", and once the outside color is scraped, it is gray concrete inside. Fine for walls, as they won't get scraped so easily, but prolly wouldn't work well on a hearth. Their heaerth stones may be different, I don't know. I am thinking of going with flagstone here for the hearth under the 30 when I ever get to install it.

 

[Highbeam]

So now I have the OAK all plumbed in. I wanted to seal the penetration to the crawlspace and also to hold the OAK plumbing really still so I strapped it down and foamed it. The kids loved the expanding foam. That 4" stub will extend about 2.5" above the top of stone.

I set and screwed the 3/4" plywood layer. I will not be using durock after all. After consulting with the mason guys, thinset is made to stick to plywood.
I will prewet the plywood and the stone to prevent the rapid drying of the mortar.

I am now dry fitting the hearthstones. These things are not perfectly uniform or flat so a thick mortar bed will be important. Also, the color varies just enough (darker one on the right) that I need to preselect every stone before mortar day. I built in a 2" overhang on all sides over the framing which will be filled with either 1/2" oak, stone veneer to match the back, or even tile. Haven't decided yet. That will be later.

 

[quotejso]

Yea cement board is more for tile i believe. Whats the r value of those stones

 

[Hogwildz]

Looking good.
First thing my mind pictures is a 1/4 log or 1/2 log horizontally installed up against the face of the base covering all 3 sides.
I'm going to keep that in mind when I do my heart for the 30.

Are you grouting between the stones, or just snugging them tight together? Do they have those little nubs to pre-create a grout space?

 

[Highbeam]

Yea cement board is more for tile i believe. Whats the r value of those stones

The stones have no special R-value, it would be the 2" of concrete which according to the charts gives me about 0.2. The BK needs no R-value, only "spark protection".

 

[Highbeam]

Looking good.
First thing my mind pictures is a 1/4 log or 1/2 log horizontally installed up against the face of the base covering all 3 sides.
I'm going to keep that in mind when I do my heart for the 30.

Are you grouting between the stones, or just snugging them tight together? Do they have those little nubs to pre-create a grout space?

I'll paint the skirt black first. Then have the cabinet maker cut and finish the oak. This can be temporary or permanent if I like it. If I put a mantle up above the stove then I think it would be cool to coordinate the materials. Like a log mantle and half round log skirt would match up real nice. I'm not very artsy so this is tough.

I will/must grout between the stones with sanded grout to attain a UL spark barrier. Plus I want to. It will be a dark grey grout and somewhat rustic, applied with a grout bag in an attempt to fill the very deep gaps. There are no little nubs and since the stones are irregular the spacers won't work so this will be an eyeball job. Shooting for 1/2" spacing but want to hold the perimeter of the stones to a straight line so the grout lines will have to be irregular.

I am using polymer modified thinset mortar. 1/2" notch applied to the plywood and then also backbutter the stones with the notches 90 degrees apart. Idea is to get a thick grout bed so that I can level the surfaces of these irregular stones and keep the stove from rocking. I'm a little nervous about the whole mortar operation.

 

[sequoia]

I'll paint the skirt black first. Then have the cabinet maker cut and finish the oak. This can be temporary or permanent if I like it. If I put a mantle up above the stove then I think it would be cool to coordinate the materials. Like a log mantle and half round log skirt would match up real nice. I'm not very artsy so this is tough.

I will/must grout between the stones with sanded grout to attain a UL spark barrier. Plus I want to. It will be a dark grey grout and somewhat rustic, applied with a grout bag in an attempt to fill the very deep gaps. There are no little nubs and since the stones are irregular the spacers won't work so this will be an eyeball job. Shooting for 1/2" spacing but want to hold the perimeter of the stones to a straight line so the grout lines will have to be irregular.

I am using polymer modified thinset mortar. 1/2" notch applied to the plywood and then also backbutter the stones with the notches 90 degrees apart. Idea is to get a thick grout bed so that I can level the surfaces of these irregular stones and keep the stove from rocking. I'm a little nervous about the whole mortar operation.

How do you plan on cutting the concrete stone to fit around the OAK? I've tried a stone chisel with less than stellar success.

 

[Highbeam]

How do you plan on cutting the concrete stone to fit around the OAK? I've tried a stone chisel with less than stellar success.

I've been able to cut concrete with a dry abrasive blade in my circular saw. It isn't a clean job but it can be done. All of the back stones will be cut down to about 9" or almost in half. Then one of those will be cut into three pieces to allow for the OAK. I will probably try to cut a little chunk (about 4x4) to fill in behind the OAK. I'll show the layout soon.

 

[sequoia]

Ok.
Now does the black pipe connect directly to the back of the stove?
Also, what is the size of that black pipe?

 

[Highbeam]

Ok.
Now does the black pipe connect directly to the back of the stove?
Also, what is the size of that black pipe?

Yes, the black air inlet connects directly to the stove. 100% of the combustion air for the BK, and my previous heritage, is taken in through a single snout.

So the black rigid pipe is 4" and the snout on the stove is 3" so there will need to be a transition there somewhere. I wanted rigid pipe sticking up out of the hearth since replacing a crushed piece of flex inside the hearth will not be an option. I chose 4" for better flow but also because you can't get 3" rigid duct at the hardware store. Bigger is better for less flow restriction.

 

[sequoia]

Yes, the black air inlet connects directly to the stove. 100% of the combustion air for the BK, and my previous heritage, is taken in through a single snout.

So the black rigid pipe is 4" and the snout on the stove is 3" so there will need to be a transition there somewhere. I wanted rigid pipe sticking up out of the hearth since replacing a crushed piece of flex inside the hearth will not be an option. I chose 4" for better flow but also because you can't get 3" rigid duct at the hardware store. Bigger is better for less flow restriction.

Thanks.

 

[quotejso]

Yes, the black air inlet connects directly to the stove. 100% of the combustion air for the BK, and my previous heritage, is taken in through a single snout.

So the black rigid pipe is 4" and the snout on the stove is 3" so there will need to be a transition there somewhere. I wanted rigid pipe sticking up out of the hearth since replacing a crushed piece of flex inside the hearth will not be an option. I chose 4" for better flow but also because you can't get 3" rigid duct at the hardware store. Bigger is better for less flow restriction.

Does that stove require outside air hell my house is so leaky that I doubt I would need it.

 

[Highbeam]

Does that stove require outside air hell my house is so leaky that I doubt I would need it.

The stove doesn't require outside air but the law does. My stove would not have passed inspection without the outside air hookup. This was the case with both stove permits I've had in this home. Different inspectors but in Pierce County which includes big cities like Tacoma. Plus, I like the idea of burning outside air instead of heated and humidified house air.