Need to extend and Retile an existing hearth - need advice

[Old20sHome1985]

Hello everyone,

I am new to this forum. I have found a ton of great information, but would like to see if I can get some clear advice on something.

I bought a house last year, 1920s home. I love the house and it has a lot of character. However it came with the dreaded Vermont Castings winter warm wood stove insert in the fireplace. The stove was completly toast. Everything was warped and so on and I am buying a new wood stove.

Went and looked at a new Avalon Olympic Wood Stove insert to heat my home. I like the simple function and the way it works. I am 29 years old and have burnt wood my whole life at my parents house.

My problem is the requirements for the new stove and the existing hearth.

The current hearth extends 19" from the face of the current fire place opening. It is a brick laid hearth, with concrete on top and then tiled with 1/2" tile. However for some strange reason it is sloped downward. Highest point at the opening to the fireplace is 1-3/4" above the finished hardwood floor.

The stove I am looking at purchasing says the Hearth needs to extend 16" from the face of the door. NFPA states it needs to be 18", so we will use that number. The stove will extend past the face of the fireplace 8-7/8", which means the hearth pad needs to be a total of roughly 27" from the face of the fire place. That is 8" more then what is currently there.

The wood stove instructions state that the hearth needs to be minimum .018" non combustable or 26 gauge material.

What I would like to do is remove the old tile, and chip away some of the old concrete to level it.

Then I would cut the required amount (8") out of the wood floor to expose the sub floor. I would then put a piece of 26 gauge sheet metal on the subfloor, then perhaps one layer of 1/2" concrete board to fill the 8" gap cut from the wood floor. This would be even with the level of the now leveled existing concrete.

Then perhaps add another layer of 1/2" concrete board to the entire hearth area to tie it all together and provide a nice firm and even base for the new tile. I would then tile the new hearth and trim it out with wood. This would sit 1-3/4" off the finished floor, even with the existing fire place floor.

Will this work? Am i going about this the right way or am I over-engineering/under engineering?

Any suggestions would be helpful.

Thanks again

 

[fossil]

Well, first of all, the manufacturer's number trumps NFPA, so 16" is what you're after. That 16" doesn't need to be a continuous horizontal surface measured out from the face of the insert...just a horizontal measurement out to the nearest combustible flooring. So, if you're up to using a simple non-combustible hearth pad on top of the wood flooring material out in front of the existing hearth, then there's no reason to extend the hearth unless you just want to. Then you're down to leveling the existing hearth surface, which can probably be done fairly simply, I'd think. Rick

 

[Old20sHome1985]

Ok. Thank you for the input. Depending how the demo of the old hearth pad goes, I may go that route. However, with anything I do, I want to do it once and have it last. Because when this stove goes in, I expect it to be there for 20+ years before I even decide to move it. And since I will have everything torn up, I would like to make the hearth pad that I think would take care of all of the needs and looks I want. Again, I may tear it apart and say "screw this", level it off, retile it and use a hearth extension.

That being said, If i go for the 16" requirement, then I am looking at extending the hearth pad 6" to meet the requirement. So, if I cut 6" out of the wood floor and expose the sub floor, does it stand to reason that the construction I mentioned before will be acceptable? I know 6" is not much, and it may seem trivial, but I am just asking. If I use sheet metal to line the subfloor, then use a layer of cement board (thickness and brand to be determined) to make up the height difference between the sub floor and existing concrete, and then a layer of concrete board to cover the entire surface to tie the assembly together and make up the difference to the existing fire place floor level, do you guys think this is acceptable? Will it be strong enough to any possible fluctuations in floor movement?

I have attached picture of the existing hearth pad. It doesnt clearly show the broken and cracked tiles, and the second photo slightly shows the pitch of the hearth pad.

Had anyone extended a hearth pad in this fashion or had a similar problem?

Thanks again.

 

[Hogwildz]

If you're gong to extend it, you may want to consider extending further than the minimums.
The reason I say this, is when you bring a load of wood in, you're going to lay it on the hearth prior to loading the stove, and a good wide area is much less prone to getting dirt etc on the floor, keeping it on the hearth, also making it easier to clean by just sweeping the mess up on the hearth.
I extended about 20" and sometimes wish I went to 24".
I have carpet around the hearth though, which sucks to try and keep wood debris off of.
Another reason to consider this, is embers will occasionally pop out, and the hearth would go unharmed, while the wood floor with get burn spots, pits etc.

 

[Old20sHome1985]

If you're gong to extend it, you may want to consider extending further than the minimums.
The reason I say this, is when you bring a load of wood in, you're going to lay it on the hearth prior to loading the stove, and a good wide area is much less prone to getting dirt etc on the floor, keeping it on the hearth, also making it easier to clean by just sweeping the mess up on the hearth.
I extended about 20" and sometimes wish I went to 24".
I have carpet around the hearth though, which sucks to try and keep wood debris off of.
Another reason to consider this, is embers will occasionally pop out, and the hearth would go unharmed, while the wood floor with get burn spots, pits etc.

I do agree and may extend it further for those reasons. I would rather not have to do this again and who knows what the future brings in regards to stoves, so i may extend it further.

That being said, my main concern is the construction of the the hearth itself. Has anyone extended a hearth and if so what was the extension and construction method? Is the way I am extending it seem like it will be acceptable?

 

[Hogwildz]

I extended mine, which was raised on brick with blue stone on top. The extension I kept dropped at floor level.
I put 1/2" Micore on the plywood floor sheathing, then Wonderboard cement board, then slate tiles.

What you have in mind is fine. You could also go over the existing with cement board and tile that, then put a nice wood trim around the perimeter.
Unless you must have it all flush with the wood floor, then you have more demo to do.

 

[Old20sHome1985]

What you said is pretty much what I want to do. Seems pretty straight forward too. Thank you.

All comments and suggestions welcome!!

 

[BenHS]

Hi, was there a successful outcome to this extension?

I am in a similar situation and am set to resurface my existing concrete hearth (which has been jackhammered down such that the finished tile will be flush with the surrounding floor) and have plywood and cement board to fill the extra 6” of the extension. (Seen in photos.)

I think this will meet code/manufacturer requirements but I am also aware that I could make a form and pour an extension to the existing extension, tied in with rebar. Is this option common or not adviseable for my situation?

I am concerned that the change in substrates (cement board over 3/4” ply to 4” thick concrete) will cause cracking in the tile. Is this normally dealt with via a control joint? If so, will any fire resistant caulk work?

Thanks for any insight anyone can give.