New Hearth for the Princess

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.

 

I gotz lotza popcorn HB.
This is gonna' be gooder.
How's the 30 treating you out in the shop?

 

Coming along nice Highbeam. That ultra sure is a sharp looking heater. I kinda wish I spent the money and went with the pedestal instead of the legs. Wouldn't have been that much more in the grand scheme

 

Thanks guys, the 3" semi rigid OAK will be replaced with 4" rigid coming up through the hearth. I will still use a chunk of semi rigid for the connection to the stove but it will be replaceable if it gets squished by a dog or something running around back there.

The 30 in the shop has been a fine bird catcher this year. So far 2 dead and 2 alive. I did acquire an adjustable temperature activated on/off switch (aka snap disc) to turn the blower on and off but we've had a heck of a summer and I haven't dialed in that blower install.

The only thing that pushed this hearth to the front of the list was that I need to put in the floors around the new hearth and I can't shut down the BK in the winter. It is 100% of our heat.

 

gonna be burning season in a couple months, your going to be busy

 

blaze kings rock!!!!!!!!!!

 

I miss my BK

 

Having read all the threads (on multiple sites) on the BK and WS stoves, I can understand "missing the BK" even though I have never owned one. In a way, I came to appreciate many stoves I will likely never use. Reading the experiences of others and seeing their enthusiasm for their stoves was fun for me. Kind of wish I had a setup that would allow me to use them all and a budget to own one of each. I could then burn one a couple months, switch to another until I've had the fun of learning them all. Of course, this is just a wood burners dream.

Looking forward to seeing the completed hearth.

 

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.

 

Good to see anothe Great Stuff fan!

 

That's a ton of work. I feel sorry for the poor guy/girl that will ever have to disassemble my hearth (of course I'll never be doing it haha). You mentioned overbuilt--- heck I think there's 3-4 boxes of screws in my hearth and at least 3 in my heat shield wall.
Your stove will be nice and high for easy loading and a nice view of the fire. Good job!

 

An update, I got the hearthstones all cut and placed over the weekend.

First, you can cut these things pretty easily with a circular saw and grinder style blade. It's messy but very easy to control and cut from the bottom so the saw doesn't leave marks on the face of the stones. Chipping is not a problem. I touched up the edges with a diamond cup bit on my 4.5" grinder.

I've only ever set 12" tile before and with tile you have a consistent thickness and shape to allow nice straight lines and consistent elevation so long as you use your notch trowel to set an even bed of mortar. Not so with hearthstones. They are very "natural" and not identical, not square, not flat, an not even the same thickness so the hearth was a bit of a bugger to set. I am now at ease with the imperfections of natural stone and hope to appreciate the variation.

These are 20x20 stones and it works out that the very center stone will hold almost all of the pedestal so I made sure that that stone was a little taller than the others (1/16") and very level. Also made sure that the back wall and all the front edges were aligned and straight. This means that the field grout joints are irregular.
Oh and with the huge 20x20 stones it is nearly impossible to lower a stone into the mortar with a hammer, weight, wiggling, etc. The stones are just too big to spooge out the mortar.

Next will be grout. I'm using a grout bag and the biggest challenges will be getting the grout all the way down to the bottom of the 2" deep grout joints, and also pointing the joints without making a mess of the face of the stones.

 

That's looking really nice HB.
I can't imagine trying to set those buggers. Natural stone=variation=unequal grout lines. It's all gooder and I'm sure it'll look even better once that's done.
Facing that frame with Oak would look sharp.
I set my frame in a small bead of caulk, and once set, with all the weight on top......it's not going anywhere. Couple hundred pounds of Wonderboard and tile, then over 400 lbs. of stove................

 

Looking good HB!! Those hearth stones are awesome looking!!

 

So I got the hearth all grouted and after waiting 48 hours I sealed the grout last night. Used polyblend sanded grout and 511 impregnating (love that term)sealer as I did not want a gloss on the hearth. I used a grout bag and that is really a workout for the old hands. I mixed the grout per the instructions plus a touch more water but maybe the grout baggers like it thinner. I didn't want to weaken the grout or mess up the color with extra water.

The 511 sealer is oil based and is a silicon sealer. Pretty stinky. It is strong enough to strip the black paint off of my OAK stub so it's the real deal. The goal is to reduce staining and make clean up of ash and debris easier. A little bit of that sealer goes a long ways.

Now I wait 72 hours before resetting the blazeking. We normally start full time burning in mid September so this is working out.

Photos are before sealer. Sealer slightly darkened the hearth but zero shine. I used two coats of sealer, 2 hours apart.

 

I hope that OAK is indeed connected to the outside. Some installers pull from the basement, garage, attic etc. Defeats the whole purpose of OAK. I have OAK on my pellet stove and my gas furnace. Not going to create negative air pressure that will suck in cold air from every crack in the house. Nice install. Enjoy the warmth.

 

The OAK draws air from the ventilated crawlspace under my home. This is the ideal location for OAK air since it is unaffected by wind, debris, snow, kid's pranks, etc. Short amount of tubing as well.

 

Okay, update, we're getting closer. The hearth is all sealed up and time to replace the stove. I slid the stove right off of the old 5" tall hearth onto the cart/dolly thing but now that the hearth is taller by 5" I need to elevate the stove before sliding it back onto the new hearth. Of course, this is done alone without any help. 4 2x6 chunks of lumber on each side ought to do. Would have been much easier with help since it takes three hands to lift the stove and slide the next shim under. Ugh, I had to sort of kick each additional 2x6 layer under without upsetting the stack and dumping the stove.

Once up to height I slid the long strips of 3x4" plywood under to use as ramps to position the stove without dragging it on the hearthstones. I was also a bit worried about overloading the overhanging hearthstones.

So now it sits on the hearth ready for OAK hookup and chimney hookup. My old slip section of double wall pipe, fully collapsed, was still 2" too long so I had to order a new shorter slip section. Also, I am upgrading the adapter between the ceiling support box and the double wall pipe to the new bolt on style instead of the hokey SS snap ring.

Another funny thing that happened is that the pedestal under a BK is only a three sided deal. The rear of the pedestal does not support the stove but about 1/8" above the pedestal base is a stout chunk of channel iron across the rear. Since my pedestal straddled the tallish center hearthstone, the rear of the stove sat down in the rear and created a low back. Not cool. It's hard enough keeping the smoke in the stove when the stove is level. So I cut a chunk of 3/16" flat bar and slid it under that channel iron to support the stove in back. Now the stove is level front to back and left to right.

So now I wait, and run electric heaters to stay warm. We have been getting some cold nights here in the Puget sound region.