Jotul Oslo hearth

[jeepnerd]

I'm planning on removing some wood flooring and then blocking and laying two layers of 3/4 ply flush with the top of the joist. I'm thinking of laying in 1/2" of Micore, then 1/2" of Hardy Backer (maybe two layers of HB) Then tilling it. I'll be filling in the original hearth with brick and mortar and continuing my tile over the brick to the back of the fireplace. I'll not be able to make it flush with the finish floor doing it this way, but it'll be close, I can live with that. My question is what do you think of my plan?
I know it's and ember protection only stove, but I'd rather over build it just incase I put something else in down the road. One thing I noticed in the manual was it said to use a non combustible hearth pad for ember protection and radiant heat. The radiant heat part concerned me, how hot does the floor get in front of the stove? With my install the stove itself will be on the original hearth from there forward it'll be wood under my tile extension.

 

[webby3650]

I think its over built. There is no reason to overbuild, this is a fine stove! If you replace it I'm sure it will be replaced with an even better stove, neither of which will need more than ember protection.

 

[jeepnerd]

Webby, I see you have an Oslo. How warm does the floor get in front of you stove? Do you think I could just go with 1/2" HB and tile? That adds up to around 1 1/8" which is 3/8 aff.

 

[cptoneleg]

Webby, I see you have an Oslo. How warm does the floor get in front of you stove? Do you think I could just go with 1/2" HB and tile? That adds up to around 1 1/8" which is 3/8 aff.

Yes

 

[webby3650]

Typically 1/2" is used on walls and 1/4" is used under tile on the floor. Have you considered cutting out the hardwood so the tile ends up flush with the existing flooring?
I don't notice the floor being very hot under the stove. It would have to be too hot to stand on before it would be a problem.

 

[Warm_in_NH]

My cat lays under an Oslow and the dog lays in front of it. Floor gets warm to the touch, but not too hot that you pull your hand away.

 

[jeepnerd]

Thanks for the replies. I guess if the cat doesn't combust I can do without the Micore. Webby, yes, I am planning on removing the hard wood. I'll be installing plywood flush to the top of the joist then Hardy Backer and tile.

 

[Pellet_Pete]

Wow, that looks exactly like the project I'll have on my hands once I can sell my propane insert! I'm curious - how are you dealing with the concrete-to-framing joint? I'v read on another post somewhere here that there is potential for "movement issues" with the two different substrates, possibly resulting in cracks in the grout. I haven't vetted my plan with the group yet, so it may sound bonkers, but for my situation I was planning to 1) pop out brick & mortar and put a leveling cement in the old hearth 2) lay sheet metal down, 3) frame out the old hearth with 2x4's laid sleeper-wise, 4) put a second piece of sheet metal attached to the underside of the 2x4 frame to let it "float" over the concrete section, 5) put a single piece of plywood over the existing joists and the new 2x4 frame & then cement board over that with tile, and finally 6) an expansion joint with sanded caulk at the wall.

Maybe I'm crazy to put framing where there is an existing masonry hearth. Curious what led you to the way you're doing it - maybe you can save me doing something stupid!

 

[jeepnerd]

I didn't even think of that having the potential of moving. I'm having a friend, who does tile for a living, come over in a couple of weeks to take a look at it, I'll ask him what he thinks. An expansion joint sounds like a good Idea, but has to be done in a way so that embers can't find wood framing. My first thought is to use some thin gauge angle to protect the wood some how around the joint

 

[Pellet_Pete]

I think the sanded caulk should do the trick at the expansion joint in terms of ember protection - it's supposed to function just like a grout line except flexible to deal with expansion (which would compress the caulk if anything since it's heating up).

 

[jeepnerd]

Maybe I could just use the caulk if a crack appears. I'll add some framing to the joist to stiffing the floor. The framing is already boxed around the fireplace with mortis and tenon. Maybe I'll get lucky and have no issues. I did a Google search and found a tilling forum, I'll post there and let you know what I find out.

 

[Ashful]

I'm planning on removing some wood flooring and then blocking and laying two layers of 3/4 ply flush with the top of the joist.

This is exactly what I did, and somewhere on this forum is a thread about it. Only difference is that my floor joists are roughed tree trunks, so I was able to skip the blocking and rabbet the sills for the plywood directly into the joists. This provided me the height (or lack thereof) I needed to lay cement board and red brick tiling flush with my original floor.

Please exclude the "early old lady" wallpaper. Left by previous owner, we've been on bigger projects.

 

[jeepnerd]

Thanks Joful. You replied to other post on my project. Have you had any issues with the tile or grout joints cracking? Did you use 1/2" HB then tile?

 

[Ashful]

Yes, I have, but I believe I know the cause of that. I did the carpentry work, but left my mason (he was there to point the fireplace anyway) do the leveling pour in the firebox floor, as well as lay the cement board and tile. I should have done this work myself, and just permitted him to grout the tile, as I believe he did not do a good job of getting the firebox floor level with the new subfloor, and then trowling the thinset over and under the cement board. The day it was done, I could knock on the tiles and hear hollow below several of them. No surprise, those are the few tiles that have popped loose. The grout is holding them in, so I have not removed them yet, but I can hear they're loose when I knock on them with my knuckles. I'm hoping the hollow was just under the tile, and not under the cement board, but I do fear the worst.

 

[xman23]

You can see mine in the avatar. I had the hearth in before the 3/4 oak floor. I tacked down a stucco wire mesh on the floor. Then set with mortar the interior stone and limestone border. The hearth limestone boarder is cut back 3/4 inch along the bottom edge. The oak floor tucks in under the border, for a seamless look. Actually after I did this install, I read the manual a little closer. There is something wrong with a corner installation and the ember protection in the front does not come out far enough. I have no idea what is wrong with the corner, the side door opens fully, and the ember protection in the front isn't needed.

 

[jeepnerd]

Xman, I take it you put the wire mesh on a plywood subfloor? How warm does your hearth get? Beautiful install by the way.
Joful, sound like you haven't had any issues with the transition between the masonry and wood framed floor?

 

[Ashful]

Nope. The transition, in my case, is a 9" x 7.5" walnut timber partially set into the masonry of the fireplace foundation. The next joist out from there is a 11" x 6.5" oak timber, and I have the plywood subfloor set between them, as shown in this side view of the fireplace:

 

[jeepnerd]

That's more or less how what I was thinking of doing. I'll post a picture or two of the framing from underneath tomorrow.

 

[xman23]

Xman, I take it you put the wire mesh on a plywood subfloor? How warm does your hearth get? Beautiful install by the way.
Joful, sound like you haven't had any issues with the transition between the masonry and wood framed floor?

Correct the mesh is on the plywood floor and the sheetrock walls as well. The mesh ties everything together and gives the mortar something to grip to. I learned it from a tile setter doing a tile bathroom floor on plywood. I think it is common method on a quality job, but a shortcut many leave out.

The walls are Cultured Stone, River Rock. The floor is the coolest, not sure of these numbers, but maybe 110 F surface. The walls are a bit warmer, maybe 130F. If I remember at the time, the Oslo had 2 different legs lengths, this is the higher one.

To not take up anymore room floor space, I wanted the stove back as far as possible. I thought I had it exactly the correct distance, but I must have forgotten the stone on the wall. So the stove has a rear heat shield and the single wall pipe has a rear heat shield. As I said the hearth in the front is about 1' 6", which is plenty, but the spec is more. You never open the front door, due to the one Oslo issue, ash spills out.

 

[jeepnerd]

Here's the framing from the basement. My extension will come out to the second joist.

 

[Ashful]

Ah, yes... I remember that fireplace foundation from another thread.

That's not asbestos pipe insulation, is it?

 

[jeepnerd]

No it was removed professionally before we moved in. That is micro lock fiberglass.

 

[Pellet_Pete]

My joists are running perpendicular to my hearth, and they're not the beefy full-dimension stuff you have. But then again, your extension will be in mid-span of that 2nd joist...I guess it's six of one, half dozen of the other in terms of vertical movement. I think you said something about stiffening the joist - I'm also thinking to do that (double them up at mid-span). Ideally I would jack in a new column or two, but that's not an option since my oil boiler & HW tank are right underneath!

 

[Ashful]

If you're thinking of stiffening a joist span, google "flitch plate girder". Can be done with heavy sheet metal on a joist.

 

[jeepnerd]

My joist span 16' so they may have some flex to them. I thought about bracing them with a post too. My floor in the basement is brick, I thought about removing a few and making a footer for the post. I'm thinking bridging between the first 5 or 6 joist would take care of any side to side movement.
Joful, I'll check that out.