Home Built Hearth - Did I do OK? (little long)

[moosetrek]

Well, we just moved to a new (to us) house, and are seriously missing our Englander 30 which is still back in our temporary 12' singlewide trailer house (talk about overkill!). The 900 sq ft (still overkill, I know!) house was built in 1926, and has a masonry chimney in use for venting the furnace. In the interests of quick, cheap, and easy I decided it would be better to just build a hearth, run a new chimney and get it going.

So after reading all the expert advice on the site here, and trying to find a place in the house to fit it, I copied the design on here with a couple mods. Here's what we did (accompanieed by reasonable amounts of frosty beverages, of course).
1) 3/4" OSB subfloor nailed on top of the existing floor, which was remnants of linoleum over either hardwood or doug fir.
2) boxed metal studs for air space
3) 2 layers 1/2" Durock
4) Tile

We had to compromise a couple areas that I hope will not cause problems. As they do not make Durock screws longer than 1 5/8, and I was already into the project and needing to get it done, I grabbed my handy framing nailer and the 3 1/4" nails and went to town. Once the depth was set, it worked really great; I know you're supposed to use roofing nails but again, not long enough. I used a few spiral shank nails I had lying around for extra grip.

That got the hearth pad down and secure, next step was the back wall. I am NOT a tile guy. I can build the wall/floor/etc. all day long but don't ask me to tile it! Tried it a couple times, and went running for help. Anyhow, as I figured tiling would be easier on a horizontal surface, I decided to build the back wall, tile it, and then mount it. What a mistake! I got it built (3/4" OSB, metal studs, and 2 layers of Durock - same as the floor). Still to flexy on the floor to tile, so up it went. PS - 5'6" x 5' of Durock and OSB weighs a ton. I left a couple inches of the OSB protruding on the sides, and made it about 6" too short on the top and bottom (for the depth of the baseboard) , and nailed/screwed a section to the wall that would fill in the gap along the top. Set it up and nailed/screwed to the wall.

Tiled it, and grouted yesterday. I placed 2x4 for a trim on the front edge, and will use metal studs painted to match the grout for the wall trim (using wood trim along the top wall would pretty much defeat the whole purpose of protection from combustibles!). I'll drill holes in the trim to allow air flow underneath and up the wall. Anyhow, I'll post pics soon. The only part I had any concern about was the nails underneath and in the back. However, I really doubt that nails under the tile will conduct that much heat, as they have 2" of Durock and a 1" exposed length before the OSB. We'll place the stove this weekend, and plan to use double wall stove pipe for close clearances specified in the manual. Now I just have to install the chimney!

Total time: 2.5 days
Difficulty Level: Moderate
Beer required: 12 pack (yours may vary)
Trips to Home Depot: 5-7
Total cost: Approx. $375
Tile $125
Mortar/Grout $50
Durock $100
OSB $25
Studs $35
Misc. $40

 

[edthedawg]

I dozed off halfway thru so apologies....

1 - what did you use for your spacing behind the back wall? metal studs? or wood?

2 - prob no issues from your use of nails on the base. if you mortared every mating sheet surface and it ain't movin' you did it right. sounds like you're gonna have something heavy sitting on it soon.

3 - are you sure sure SURE you checked clearances to that little kick wall / column on the left? Seems like you are in a delicate balancing act of clearances and avoiding traffic paths.

4 - What arer your R-value requirements? about 1.2 min?

 

[fossil]

I'm assuming that the manual for the Englander 30 includes allownces for clearance reductions using wall shielding. If it does not, then the rear shield you built doesn't buy you anything. I see that (or at least I think I see that) you brought the rear shield down tight against the hearth. That's not standard shield installation. It would normally be installed with a 1" air gap along the bottom edge, or at least some openings along that edge to allow air to enter. Yours may be adequately ventilated from beneath, I can't tell. Rick

 

[moosetrek]

Thanks for the responses folks! Sorry I'll shorten it up when I post final pics.

Edthedawg:
1) same as the floor - metal studs, 2 layers of Durock.
2) That was my thinking too. I didn't think to thinset the two sheets together, but too late for that now just hope fot the best. Static load, and no movement other than thermal expansion/contraction on the hearth so hopefully should hold. Stove is about 490#.
3) Wall will be well over 20" from the side of the stove - stove will be offset slightly to the right due to joist spading for the chimney install.
4) Per Englander manual, requires R=1.5

Fossil:
The manual does in fact provide for close clearance. The only deviation I have is that I have rear shield on the stove, but no side shields. To remedy that, I will fabicate a couple 16-gauge (same as the rear and factory-offered side shields) rear shield extenders that will prevent the back part of the sides from heating the wall to the rear. For the vent along the back hearth, I cut the metal studs 1 inch above the floor, and the sides will have openings to allow air in, the top will have openings to allow air out.