hearth extension for new Woodstock

[rickw]

Picked up a new Fireview a couple weeks back, need to upgrade the hearth for it. Will go in front of existing fireplace (where I had a Lopi answer insert for the last 3 years). This is an exterior chimney, with the fireplace on a joist floor (that is, the fireplace is not on a ground floor). The existing hearth pad (before I added anything) was 18" x 60" quarry tile on top of concrete. I added another row of tile (on top of 3/4" total of Wonderboard) to make it 24" x 60" when I put in the Answer insert. Now, with the new stove of sittting in front of the fireplace, I need more pad - like 36" x 60" or maybe 42" x 60".

I'd attach a pic but am stymied by Linux. Don't ask.

Question - I saw some concrete under the tile when I extended the hearth for the Lopi. what does a typical concrete hearth extension pad look like? I've heard mention of pouring it in a frame; I just assumed that maybe it was poured over the joists somehow. Anyone know how this works?

It matters because I'm considering ripping it all out and replacing it with a subfloor/durock/tile structure. If concrete hearth extension pads are always poured in a frame then I'll leave it alone and just add a few rows of tile on the front (by removing my previous extension and adding the durock/tile sandwich on top of a new section of subfloor). This would certainly be easier than demolition.

Any ideas or links?

P.S. - I can't wait to fire up the Woodstock. A real handsome stove, very friendly and helpful people at the factory. Real positive experience so far.

 

[begreen]

I'd keep it simple. It doesn't sound like you'll need to demo the concrete. The Fireview has light duty hearth requirements. From the manual:

"If you decide to build your own hearth to go over a combustible floor, start with a
plywood base. Over this apply:
1) a layer of 24 gauge galvanized sheetmetal,
2) a 1/2 inch layer of an approved non-combustible insulation board (such as
DUROCK cement board or WonderBoard Backer Board),
3) decorative non-combustible material such as tile, slate, stone or brick."

 

[Highbeam]

The extension does NOT need to be poured. There doesn't need to be any concrete at all. I would step back a bit though and look at how heavy this bugger is. How is the floor support? You've got the stove at about 500#, the hearth at a couple of hundred or more if you pour anything, and then a full load of hardwood burning in the stove, oh and don't forget the family of four all cozied up next to it. Easily over 1000#s of load on that floor that may not have been built for it.

I liked the woodstock but the hearth requirements were very large for a freestanding application without an existing brick chimney in back.

The hearth can be built per tha manual unless you need more thickness, and then you have more choices/options to make including pouring concrete or even wood framing.

 

[rickw]

I guess I wasn't being very clear. The stove will go in front of an existing masonry fireplace (with exterior brick chimney),which seems to have some sort of poured concrete pad in front of it (tiled over). What I don't know is what the hearth pad in front of the fireplace is connected to. Is it part of the chimney somehow? Can I park some of the weight of the stove on it without problems? I was planning on putting a jackpost in the basement to support at least some of the aditional load.

 

[pinewoodburner]

Call Woodstock. I also just purchased a Fireview from them and have to exend my hearth. Need 1/2 inche of Durock or wonderboard and then grouted tile. If you don.t grout the tile, you will need the sheet metal under it all. Also, if you put plywood under it all, you will spread the load to 3 or 4 joist, and they can handle the 500 lb stove just fine.

 

[begreen]

I guess I wasn't being very clear. The stove will go in front of an existing masonry fireplace (with exterior brick chimney),which seems to have some sort of poured concrete pad in front of it (tiled over). What I don't know is what the hearth pad in front of the fireplace is connected to. Is it part of the chimney somehow? Can I park some of the weight of the stove on it without problems? I was planning on putting a jackpost in the basement to support at least some of the aditional load.

Best to go down to the basement or crawlspace and investigate. It's hard for us to predict how this was made, but a look on the underside should reveal what is supporting (or not) this area.

 

[Highbeam]

Just last year I tore down my masonry chimney built in 1963. The firebox, fireplace, and chimney were built as one assembly from the foundation in the crawlspace to the rooftop. The hearth extension area in front of the fireplace's firebox, in my case about a 18" tall hearth and about 18" deep, was set on the same foundation but the blockwork was independent which allowed me to leave the main big dog base of the chimney but remove the blockwork for the hearth extension down to the poured foundation. I used the poured foundation that had supported the hearth extension to support the new beams I used to hold the floor up under my new and very large hearth pad.

So in my case, the hearth extension had its own stem walls supporting it to the poured foundation providing high strength.

 

[Todd]

How many inches do you need to extend your hearth? The Fireview only requires 8" in front since it's a side loader. But then you need 18" on the sides.

 

[rickw]

Thanks for the responses. I'll have to tear out some of of the stucco ceiling in the boiler room directly below the fireplace to see what's there. I'm leaning towards just leaving the original 1958 pad and extending it another 4 rows of 6" tile towards the front and one row of 6" tile on each side - using a plywood/Durock/tile structure recommended by Woodstock. This will give me a pad 42" deep x 6' wide; plenty big. Will probably put a jack post in the boiler room to hold everything up.

The next problem is the mantle. My wife is looking at hand-painted tile....

Thanks again.