Hearth- Airstone vs Evolve?

[SCHomestead]

We are getting a new alderlea T5, and the dealer is worried about the adhesive heat rating of the Airstone (airstone itself is class A fire rated). They sell evolve and versetta stone products. Evolve is just a nail on foam type product and is class B rated. Has anyone used any of these products that can recommend/not recommend them?
Thank you!

 

[begreen]

Congratulations. The T5 requires a non-combustible hearth. If these products are not specifically rated non-combustible they may not be ok, especially if the binders are still somewhat volatile. They probably won't combust, but will the outgas constantly and is this desirable in the home?

 

[SCHomestead]

That's one of my main concerns, and why I was looking at airstone over a polyurethane product. Airstone is air infused concrete. The hearth dealer called the manufacturer and they said they've never had a complaint of off gassing in the evolve PU product, but I was wanting to see if someone on here had used either. I saw a couple of posts of people using the Airstone with outdoor adhesive rated to 300 degrees, but I dunno if that's enough. The evolve stone is rated to 800.

 

[begreen]

It looks like AirStone may be ok, but the adhesives are not. They're just glue. I am not sure if the product can instead be installed using latex-modified thinset instead.
From the site:
AirStone Interior Adhesive is rated up to a temperature of 120˚F, and Loctite PL Premium Construction Adhesive is rated up to a temperature of 160˚F.

Is this for the hearth wall or floor? If for the hearth pad then see if they are ok for heavy objects to be place on them. The T5 is a heavy stove with the weight concentrated at the four feet.

 

[begreen]

Just got reminded of a previous thread where I did a bit more research. Airstone is for vertical surfaces, not horizontal like the hearth pad.

 

[SCHomestead]

Yes, we would be putting it behind the wood stove on the wall. We're looking for lighter & cheaper materials than stone. Thank you, this has been a more difficult endeavor than we thought 😅

 

[begreen]

I think you will be ok to use it on the wall with the T5 as long as the proper clearance is met or exceeded. The shielding is good. The T5 radiates very little heat from the back.

 

[SCHomestead]

I think you will be ok to use it on the wall with the T5 as long as the proper clearance is met or exceeded. The shielding is good. The T5 radiates very little heat from the back.

Great thank you! We exceeded all clearances 😊

 

[begreen]

What will be used for the hearth pad?

 

[SCHomestead]

What will be used for the hearth pad?

We were going to use tile. Hearth is on 4x6s, raised 6" from floor

 

[SCHomestead]

We were going to use tile. Hearth is on 4x6s, raised 6" from floor

2x6" I meant

 

[begreen]

That will work. Put a plywood cap on the 2x6s, then cement board, then use latex modified thinset to set the tiles.

 

[SCHomestead]

Thank you! We were going to omit the plywood bc he beefed up the hearth good with supports, do you still recommend it? It's a large hexagonal hearth, widest in back at 6.5' and 39" in front. It's over a basement, which is why we want a lighter stone weight.

That will work. Put a plywood cap on the 2x6s, then cement board, then use latex modified thinset to set the tiles.

 

[stoveliker]

I think that to hold the heavy stove and not break, cement board likes to have a continuous backing structure. It's not good with point loads when unsupported imo.

 

[SCHomestead]

I think that to hold the heavy stove and not break, cement board likes to have a continuous backing structure. It's not good with point loads when unsupported imo.

Okay, will do! Thank you very much!

 

[begreen]

We were going to omit the plywood bc he beefed up the hearth good with supports, do you still recommend it?

Yes. The T5 is a heavy stove. 1/2" or 3/4" plywood under the cement board will add a great deal of stiffness. The underlayment needs to be rigid so that the top can't flex. Otherwise there is a risk of the tile joints or maybe the tile itself cracking.