Building My First Hearth

[MurphyMacmanus]

First off great site with tons of good information.

I'm starting to build my first hearth for a newly acquired stove. Its a used traditions by earth stove (which i believe is owned by lennox now). The hearth is going on-top of a concrete slab and up against a plaster wall. The stove manual states it must be placed on a 3/8 hearth pad or equivalent. What R value is that asking for? I assume since whatever I build is going to be over a concrete slab it should be fine. I am planning on make the base out of 16x8x4 cinder blocks covered by slate tile if it matters.

My major question is on the rear clearance. The stove manual states it needs 6in rear clearance to a protected wall and 13 3/4 to an unprotected. What R value do I need to constitute a "protected wall", or does that depend on local building code ? I'm either going to cover the plaster wall with brick then slate tiles or frame it out with metal 2x4's, durock, then tiles depending on what is needed or suggested from here. Any suggestions, guidance, etc?

Thanks

 

[daryl]

I used durarock spaced out 1" from the wall open at the bottom and top. You can then tile or stone the face of the dura rock.I do not know what the R value is but the NFPA 211 approves this type of wall sheild. The width is determined by placing stove or a cardboard cut out at the clearance needed. Using a tape measure go from stove corner too back wall at what the un wall clearance is suppose to be that well be your wall width.Same goes for the height.You should also use double wall stove pipe so you do not have shield the whole wall for stove pipe clearances.

 

[firefighterjake]

It sounds as though your cinderblock/slate tile idea will be OK . . . since it is going over a concrete slab. I did have a question about this however -- are you planning on cementing the cinderblocks together and/or putting down Durock or some similar material over the blocks. I wouldn't worry about any flex from the concrete slab below, but I would think that applying the slate tile directly to cinder blocks without a "backer board" or at the very least "tying" the blocks together might allow some flex between the individual blocks and tile resulting in cracks and pop offs. I also would check with your insurance company and local AHJ (typically the Fire Department) to see if the proposed hearth is OK and meets local codes . . . sometimes there are more strict rules . . . for example here in Bangor the Inspector requires listed floor protection for all solid fuel burning appliances.

I don't think you need to worry so much about the R-value requirement of wall protection. You would want to follow NFPA 211's methods to get the wall protection. Some techniques honestly are rather simple and (in my opinion) ugly (i.e. using plain sheet metal . . . although I suppose some nice copper sheeting might look good). I suspect that most folks who go with wall protection go with Daryl's suggestion of using Durock, spacing it out one inch and leaving a gap between the top and bottom of the sheet . . . and then they cover it with tile, stone or a decent paint.

 

[MurphyMacmanus]

Thanks for the replies. The cinder blocks would be cemented together just as if the hearth was being made out of them with no slate. Depending on how the finish looks I may apply durock over-top just to get a nice flat base to apply the slate to.

What is the preferred method to gain that 1in of air space between the durock and wall for the backer board? Metal 2x4's as a frame? How much of a space should be left for it to be considered "open" ? Is a few slits cut in the grout lines to hide them good enough or is more airflow needed?

 

[daryl]

Through the years I have used a lot of different things long screws w/ a non combustible spacer,2 X 2 metal studs.If I remember correctly 50% of wall width. So if your wall is 48" wide 24" has to stay open 1" X 24".You should also check your manual sometimes by adding double wall you no longer need to use wall protection.

 

[MurphyMacmanus]

Thought I'd update this. Finished it up a while ago an just got around to a few pictures. Hopefully it will be cold enough soon to get a fire going in it.
The flash reflected in the coat of sealer on the slate is giving it some glare in the pictures. What I ended up with was 1.5in deep spacers cut out of cement board to create a 1.5in air space covered by 1/2in layer of cement board (durock) with the tiles attached to that for the wall protection. The base is concrete blocks over a concrete slab covered in slate.

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now that this project is done, time for some paint and trim in the room.


Little bit of food for the stove...

 

[MurphyMacmanus]

Need to pick up a kettle to sit on the trivit. Copper or black? Any opinions?

 

[szmaine]

Copper - pick up some of the colors in the slate.

Looks terrific! I really like slate.