Building up a hearth on a cement floor

[mrbelliveau]

Hi folks,

I'm looking at designing and building a tile (or maybe stone) hearth for my wood stove. Right now, it is resting on a cement floor and I would like to put laminate floor down. So I figure it would be best at this time to build the hearth, then the flooring can butt up against the hearth rather than the hearth sitting on the laminate.

It is in the middle of the wall, not in a corner. So the hearth would have a floor portion and a flat wall portion - no corners, yay! I think that's most of the big picture... Here are the main steps I'm looking at for this project. I want to make sure I'm not missing any big pieces before I start into this. So any feedback on this plan would be hugely appreciated!


Starting on the floor, working up:

1. Start with a layer of vapor barrier, resting on the cement. I read somewhere that this will prevent any moisture from rotting the wood. Not sure where the moisture would come from, but I figure it can't hurt.
   
   
2. Resting on the vapor barrier, a 2x4 frame (2x4's on edge), with interior "studs" 2x4's, 8" OC. I figure with the weight of the stove, my interior 2x4's should be this close together. Any thoughts on if this should be further/closer than 8"? Then fasten this frame to the adjoining wall studs/bottom plate using screws. I figure with plywood, Durock, tile/stone, and a nearly 200lb wood stove on top of it, this platform isn't going anywhere. So I'm considering foregoing cement nails at this stage to fasten it to the cement floor. This whole frame would be designed, of course, with the appropriate clearances in the manual for my wood stove.
   
   
3. 1/2" plywood on top of the 2x4 frame, fastened to the 2x4's using 2" nails.
   
   
4. 1/2" Durock on top of the plywood using Backer-On screws.
   
   
5. Put on grout, tile/stone. As you can see, I've been thinking more about the first few steps... I figure whatever I use in this step, it will need Durock or something of the sort as a backing. Is there anything else I should be considering on the floor platform?
   

On the wall:

1. Cut out drywall where I want the hearth. Again, check manual for clearances. Patch/replace any cuts that I make in the vapor barrier behind it.
   
   
2. Replace drywall with 1/2" Durock. Again, what should I use as a fastener here? And should I build out a 2x4 frame at this stage? Or can the Durock be flush with the existing drywall?
   
   
3. Grout, tile or stone. Is there anything else I should be considering on the wall portion?
   

So that's what I'm planning for now... I've never worked with Durock, tile, grout, or stonework before but am excited/nervous to try it. Does anyone have any recommendations for what I should look for in a stone (material = granite?), or tile (tile that is sufficiently heat resistant?).

Again, never tiled anything before... any tips on working with these materials?

A huge thanks in advance!
-Matt

 

[electrathon]

Are you wanting to raise the stove up? If not, why are you not just going to tile the concrete floor? A lot less work and a better finished product.

 

[mrbelliveau]

Are you wanting to raise the stove up? If not, why are you not just going to tile the concrete floor? A lot less work and a better finished product.

Good point... hadn't thought of it! That sounds quite a bit easier, especially since I'm going to try to do this by loosening the screws in the adjustable stove pipe and jacking the stove up and working around/underneath it. I'm only one man, so I don't want to bother trying to move it laterally.

So you're talking just plywood, then Durock, then tile/stone on the floor? Would you even bother trying to fasten the plywood to the floor? Or just have the weight of the stove hold the whole thing in place (plus the laminate butting up close on either side).

What about the wall portion? Could my Durock be flush with the existing drywall? Or should I build out a bit? I have probably ~14" to work with between the stove and the wall. So I think I've got plenty of room to build a 2x4 half-wall, but if I could avoid it I would.

Thanks!

 

[electrathon]

The floor is concrete, you have no fire safety issues with it. Put down thin set and put your tiles on it, grout, done (sort of). Adding plywood and other stuff would only be done if you want to raise your stove.

What is on the wall now? Is it legal or are you trying to fix an issue?

 

[DougA]

I laid 6" cinder block on their sides mortared right onto the cement floor. That gives you a smooth surface to lay ceramic tiles or stone on. If I had to do it again, I would use 8" cinder block to get another few inches up. Raising the hearth is much easier for loading your stove, for viewing and it helps keep small kids away from the hot stove. Don't use plywood at all for a hearth if you already have a cement floor - not needed.

 

[mrbelliveau]

The floor is concrete, you have no fire safety issues with it. Put down thin set and put your tiles on it, grout, done (sort of). Adding plywood and other stuff would only be done if you want to raise your stove.

What is on the wall now? Is it legal or are you trying to fix an issue?

I guess I didn't think tile could sit directly on a cement floor. Thought you needed something underneath... But that makes life a lot easier.

I'm mainly looking to do the wall for aesthetic purposes, to match the floor. I've got lots of room in my clearances according to my wood stove's manual.

 

[mrbelliveau]

I laid 6" cinder block on their sides mortared right onto the cement floor. That gives you a smooth surface to lay ceramic tiles or stone on. If I had to do it again, I would use 8" cinder block to get another few inches up. Raising the hearth is much easier for loading your stove, for viewing and it helps keep small kids away from the hot stove. Don't use plywood at all for a hearth if you already have a cement floor - not needed.

I like that. I was trying to think of other reasons why I would want it raised! But definitely makes loading it a lot easier. So avoid flammable wood in making a hearth. Makes sense.

Any thoughts on my original idea to do Durock on the wall? I'd like to do it as well for aesthetic purposes, to match the floor section. Cut out drywall, then replace with Durock? Or should I build out?

Thanks for the help!

 

[usmc1371]

You can lay tile right on the concrete floor with just thin set. The reason for cement backer board under tile is to give the tile and thinset something to adhere to that is rigid. There may be a specific kind of thin set for concrete applications so google that up.

 

[electrathon]

If you are ok and safe now with your clearances you can just tile the wall. If you are needing a heat shield you want to set durock with a 1" air gap and tile on the durock.

As to the raising of the hearth, it is a form or function issue. From a purely thermal issue, the lower the stove the better. If you want the look or style of a raised hearth, that is ok too. I did cringe a little when Doug said he set the cinder blocks on their side. They are absolutely not stressed to support weight on their side. As long as your stove is light it probably is not an issue. Depending on the stove foot design you could be putting a couple hundred pounds of stress on a spot designed to not have stress on it.

 

[BobUrban]

x2 on what Electrathon said - Cinder blocks are designed to be rigid in only one direction up/down - I know for sure I would not feel safe with my stove supported by cinder blocks laying on their side. I also find it potentially a serious code issue and possible access for insurance denial of a claim.

As mentioned: Simplest solution for you: Tile floor and wall - Google how and what materials are best - DONE.

Raised hearth is a nice option for the above mentioned reasons but adds to the work - not a lot, but some.

Personally if it were my project I would raise it - just me. But either way I strongly recommend removing the stove and getting it out of your way to do the project as apposed to attempting to work tile/stone/other under a precariously jacked up stove without much experience laying tile, etc.. Ask a friend for help or move it yourself - if you are on cement it will be really easy and the project will be so much easier.

 

[DougA]

I did cringe a little when Doug said he set the cinder blocks on their side

I guess I should have been more specific. I used cement blocks, which I thought were the same as cinder blocks. After checking, there is a difference and cement blocks are stronger. My guess is that it's a regional thing for what they are called. I always called them concrete blocks.
I got the solid ones that are square on all sides with smaller holes in the middle. That makes putting tile on the sides very easy. Plus, I assume anyone would be putting a ceramic tile or stone on top which will distribute the weight. I put my 800 lb stove on without even questioning the strength. There should not be any problem with any wood stove.

 

[electrathon]

That made me feel better Doug. I have seen people put cars on cinder blocks long side up. If you have ever seen a test you can support a car on them. Tap the side with a one pound hammer and the block will collapse.

 

[mrbelliveau]

Thanks for all the great responses everyone... I'm contemplating all of the stubbed toes with a raised hearth and am leaning towards putting tile directly on the slab. It's very level (great work from the crew that poured it) and would be a nice option considering we're tight on space in that area around the stove. And the more I think about it, Bob, the more it looks like moving it is going to seem exceedingly necessary. Before I get going with the rest... any tips on moving a heavy wood stove (and then back onto the new hearth, without scraping across and disturbing newly installed tile)?

 

[BobUrban]

any tips on moving a heavy wood stove (and then back onto the new hearth, without scraping across and disturbing newly installed tile)?

I moved my old stove off my hearth and new NC-30 onto it without too much trouble and my hearth is raised a little bit. I would start by cleaning the stove really well and removing the heavy parts that are easy like door, fire bricks etc. This may not be necessary to get it out of the way but will help when putting it back. Actually to get it out of the way use a floor jack and 2x6 or so - Jack up - role out of the way. With a cement floor this should be rather easy. Going back may not be as simple due to the lip created by the tile but still an option if you are creative, have decent wheels on the jack and something down to protect the new tile. If this is not an option and it is on legs you can put the legs on those plastic slidy things - first two... slide... then four... slide into place. Mine I just was slow, diligent and got it there but I am not using pretty tile - my hearth is 100+ year old brick pavers.

 

[begreen]

That install sure looks close to the wall Bob. Is that double-wall stove pipe.

 

[BobUrban]

Photo trickeration - and DBL wall. 16" from the drywall.

 

[DougA]

Moving it:
Two medium strong guys
or one guy with an appliance cart with straps around the stove.