Hearth question

[calaisvermont]

I just bought a Hearthstone Heritage stove and I'm in the process of planning a hearth. I'd like it to be as flush to the floor as possible, with sixteen inches clearance on both door sides. the plan is to dig into the flooring down to the subfloor, and use that to build onto. Trouble is, I didn't take into account that I need an r value of 1.2.

what is the 'thinnest' approach to getting to the tile layer? And what is the layering order in the sandwich? My sense is, from what I've been reading, that a 1/2 inch of micor and a 1/2 inch of hardyback wil do the trick, then a 1/4" tile surface? Is there any better approach?

Thank you very much,

Erica

 

[DAKSY]

I think you have it nailed...

 

[jtp10181]

If you can find 1/4" tile backer board (non-combustible) that might save you 1/4". I don't know if such a thing exists though.

 

[calaisvermont]

Thank you very much for input. I'm HOPING I can find micor today. Hoping it's not hard to find. So I'm looking for something called micor 300, right? Not sure what the 300 stands for....

 

[edthedawg]

Yes 1/2" Micore-300 is what you want. Micore-160 is the lightweight variant, which is not what you want.

Your local distributor may be as follows:

KAMCO SUPPLY CORP OF BOSTON
484 AVENUE D - SUITE 10
WILLISTON, Vermont 05495
Phone: 802-658-3730
Fax: 802-658-4131
Website: www.kamcoboston.com

Definitely call first. Good luck finding it.

And as someone who tried and failed miserably to do a flush hearth for my own Heritage last year, please - I beseech you - heed my warnings:

1. Triple-check all your front AND back clearance requirements ahead of time! I wound up building mine about 8" too short in every direction. So I built a cheap raised hearth from metal studs, Durock, and thinset/tile/grout.

2. Go with 18" all around - again, AFTER verifying your rear clearances. The US standard is evolving to the Canadian min clearances. You will want the extra coverage.

3. Don't use any pre-mixed tile adhesives. Don't use Hardi-Backer. Durock-"NEXT" is also counter-recommended.

4. I'd actually recommend 2 layers of the 1/2" Durock over the Micore, just due to flex & loadbearing capacity. You're putting a mighty heavy stove there. With just a single layer, I'd mark out the "line" where the feet will wind up, and put in a thin strip of Durock in place of the Micore just in those spots. That'll give you better support for the hearth surface during the install. If your hearth winds up just a little above flush, there are plenty of fine tapers trim details you can add around it to greatly ease the transition from the wood floor.

5. Also - kneeling or bending all the way down to the floor for a flush install kinda sucks. I almost want mine higher sometimes.

 

[calaisvermont]

Man. Why are you the ONLY PERSON who has been able to help me? Not the stove store OR the tile store OR the stove manufacturer? No one around here has ever heard of micor. THANK YOU.

Two layers of durock kicks the stove up another half inch, and I can only go to the subfloor level (deeper would mean too big a carpentry project...). I'm really hoping to stay as flush as I can. But you also say forget the hardybacker? So is the final sandwich 1/2 inch micore, then 2 1/2 inch layers of durock, then tile? What do I use for a tile adhesive if not a pre-mixed kind?

Good god. I thought this was going to be simpler...

 

[edthedawg]

Relax, Erica (oops - edit - didn't see yer name in the OP. Sorry 'bout that!)

It is simple

Use a product called "Versabond" from Home Depot. Great DIY'er/Pro-used thinset mortar. Comes in 50 lb bags as powder for about $15 ea. Get yourself a $5 margin trowel, mix up about 1/3 of a 5-gal bucket at a time. Add water bit by bit, and stir it up real good til a powder-free dollop will hang upside down from the trowel, like soupy peanut butter, almost.

Once you set the Micore into the floor, use a $5 floor trowel (1/4x1/4 square notch) to spread thinset to the Micore. Then set the Durock on top of the Micore, and then the tile on top of that. All w/ versabond. Get 2 bags.

Honestly, it wouldn't be a horrible idea to put a bed of thinset on the subfloor below the micore and press it into that. Or 1/4" Hardie board would be ok there, on the far side of the Micore, if you really wanted to level out the subfloor surface more there. You'd bed Hardie in thinset, as well, AND screw it down to the subfloor, if you used it.

In the end, you just don't wanna have your pretty, expensive stove to sink thru the face of your pretty, expensive tiling job. Hence my recommendation to double up the Durock or/and add a solid strip of it in the Micore layer, where you know the stove legs are gonna sit.

If your finish tiled surface winds up more than 1/4" proud of the surrounding finish floor, it's a fairly simple task to add a beveled trim piece around the whole thing, to make the transition such that you'll hardly ever notice it's there.

Hope this helps. I'm certainly happy to when I can

 

[calaisvermont]

Fantastic. Could not be more grateful. I will print this out and read it seven times and on seventh read I am sure to be ready!!

Thanks again so much,

Erica

 

[Wet1]

I'll add one other tip. You might want to mix that thinset with a large paint mix attached to a drill (a beefy one if you have access to one). HD or Lowes will have 5 gal. paint mixers that will attach to a drill. It takes a fair amount of mixing to get the thinset properly mixed (no clumps) and I can promise you'll be really tired of mixing if you have to do two bags by hand!

 

[Wet1]

Also, if you can't get the hearth fairly close to the same height as the floor, I'd suggest making it a raised hearth. I've seen some sticking up 1/2" to 1" and they look strange. Raised hearths are typically easier to live with as well in daily use. You can use hollow 4" block or steel studs to raise the hearth, the Durock and air gap will give the R valued w/o using or needing the Micore.

 

[edthedawg]

I poked a tiny bit and found something along the lines of what I was thinking here...

(broken link removed)

Option #2 shows a "flush reducer" (no, not a plumbing term!) that you could miter and butt up against your tilework (or rip narrower, if desired).

Note: This is just one example of one particular floor manufacturer's trim options that this one installer happened to show here. I guarantee if you wander the aisles of Lowes or Homers, you'll find Things Just Like This that you can adapt to your particular finish height, floor finish, etc. Some simple nailing will take care of securing it to the floor. Leave it gapped about 1/4" around your tile work, and use a sanded caulk that matches your grout color to fill that gap.

And since i tend to poof from time to time, feel free to PM me if you ask a question and don't get a timely response

(tho one might conjecture there's plenty of other random people on the internet willing to offer free advice whenever the need arises...)

 

[calaisvermont]

OK so I hope no one rolls their eyes...
but I went back to the tile place today and someone walked me out to the 'granite boneyard' and they sold me on a huge slab of beautiful, reduced-price granite. I thought...man. That seems a LOT easier than tile. Just plunk 'er down. I'm still going to dig down to the subfloor plywood...and I think the granite will stick up about a 1/2 inch. They're going to soften all the edges and offer up nice rounded corners. I'm hoping this doesn't look wicked strange...I'm but it all just seemed much simpler than all the layering. It's one beautiful stone too....I'll admit it. It was an impulse buy. But it was 200 bucks for a 2 thousand dollar slice of granite, and my guess is that in the end, it'll come out to be around the same price as all the tile and layering was going to cost. And this way I certainly won't have to worry about flexibility in the sub layers....
??????
Hoping I made the right choice....

 

[SolarAndWood]

Definitely the right choice. Replaced tile with a single piece of stone in the last house and it was beautiful. There seem to be a lot of those stone yards on the back roads of VT.

 

[calaisvermont]

Really glad to hear that you went this way and were happy with result. I'm kind of on the fence about the idea visually but man. It sure seems easier. And yeah. There's a lot of good rock around here.....

 

[Archer39]

Also, if you can't get the hearth fairly close to the same height as the floor, I'd suggest making it a raised hearth. I've seen some sticking up 1/2" to 1" and they look strange. Raised hearths are typically easier to live with as well in daily use. You can use hollow 4" block or steel studs to raise the hearth, the Durock and air gap will give the R valued w/o using or needing the Micore.

what is this hollow 4" block you speak of?

I am brain storming ideas for when i build mine and it sounds like an alternative to steel studs.

 

[edthedawg]

*whistle* TIME OUT Hopefully i'm the one missing something here, Erica...

You still have a Heritage?

You have a new slab of solid granite? It's about 2" thick? That gives you an R-value of 0.166. (.083 per inch)

Are you still putting the 1/2" Micore board down below the granite? That's R=1.030.

Just curious how the R1.2 is gonna happen. 1/4" of thinset in there gets the cumulative R-value up high enough. I just wanna see the Micore in there still

 

[Wet1]

calaisvermont, Ed is correct... you have done almost nothing to meet the R requirement by going with just the slab of stone (it's a poor insulator). Certainly not to code and that stove burns warm in that frontal area under it.

 

[Wet1]

Also, if you can't get the hearth fairly close to the same height as the floor, I'd suggest making it a raised hearth. I've seen some sticking up 1/2" to 1" and they look strange. Raised hearths are typically easier to live with as well in daily use. You can use hollow 4" block or steel studs to raise the hearth, the Durock and air gap will give the R valued w/o using or needing the Micore.

what is this hollow 4" block you speak of?

I am brain storming ideas for when i build mine and it sounds like an alternative to steel studs.

I used hollow core 4"x8"x16" concrete blocks in place of the steel studs, you can get them at HD or Lowes for about $1.10 each. I spaced them and then covered them with a couple sheets of Durock (all bonded together with thinset). You can add perlite if you want even more protection, it's about $12 for a 4 cu ft bag (plenty for a hearth) on ebay.

 

[firefighterjake]

*whistle* TIME OUT Hopefully i'm the one missing something here, Erica...

You still have a Heritage?

You have a new slab of solid granite? It's about 2" thick? That gives you an R-value of 0.166. (.083 per inch)

Are you still putting the 1/2" Micore board down below the granite? That's R=1.030.

Just curious how the R1.2 is gonna happen. 1/4" of thinset in there gets the cumulative R-value up high enough. I just wanna see the Micore in there still

No, you're not missing anything Ed . . . as I was reading through the thread I saw Erica's post and said the same thing . . . "Whoa! She still needs the R-value for that hearth!"

On top of this, she will want to see if the insurance company and fire inspection (if required) will approve the install . . . as I have stated many times before . . . some places require listed floor protection (i.e. commercially made product or UL listed Durock).

Good catch.

So Erica, the bad news is that you can't just put down the granite slab and be safe . . . but the good news is that it will be easier than tiling and should look wicked sharp when finished.

 

[edthedawg]

Did we scare poor Erica away?

 

[Wet1]

Maybe she decided to stick her head in the sand? Sometimes that's easier in the short run...