# Micore 160 or Micore 300 for hearth?



## Kate1569 (Jan 21, 2011)

There seems to be some confusion about which one has a better R value. I found some comments on this board that say Micore 300 is better, however, if I read the Technical Data Sheets correctly, Micore 160 has better insulating properties:

Micore 160:

k-factor: .39
R-value (1/2" board): 1.27

Micore 300: 

k-factor: .49
R-value (1/2" board): 1.03

To my knowledge, a low k-factor is good, because it means less conductivity. So it seems to me that Micore 160 would be the better choice. However, and I am also weighing those factors, Micore 300 is mechanically stronger, which might (I am not sure if it would) be a factor when using it under tiles (with CBU over it, over course).

Anybody have any insights on this? I'm right now facing the choice of ordering one or the other.

Thanks everybody.


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## begreen (Jan 21, 2011)

If the insulation requirements are sufficiently met, I like the higher density micore 300 for a hearth.


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## Eaglecraft (Jan 21, 2011)

BeGreen said:
			
		

> If the insulation requirements are sufficiently met, I like the higher density micore 300 for a hearth.



BeGreen:

When I discussed Micore products with my supplier in Salt Lake City, he advised me to purchase Micore 300 because he felt it was a better quality product.  Depending on specific R requirements Micore 300 can be obtained in various thicknesses, or for that matter doubled up.

Here is what US Gypsum says about its products:

Micore 300 

Micore 300 board does it all. Itâ€™s a superior substrate for fabric and vinyl-covered wall panels, office dividers and tackboards, and an excellent core for chalkboards, stove boards and other similar applications. With outstanding resilience, superior machinability, and high density, Micore 300 board has the best surface hardness of any Micore board. The boardâ€™s smooth surface laminates easily with various finish materials such as vinyl, fabrics and steel. It is compatible with most water- or solvent-based adhesives.

Thickness 3/8 inch (.375)
7/16 inch (.438)
Â½ inch (.500)
5/8 inch (.625)
Â¾ inch (.750)
Tolerances Thickness .015 inch sanded and coated
Thermal Conductivity k Factor = .49
R Value (1/2 inch board) = 1.03

Micore 160 

For superior performance plus savings, Micore 160 board adapts to a variety of design applications. Ideal for open plan partitions, office screens, dividers, tackboards and various other applications. The board combines lightweight properties with the strength and stability of heavier boards. And that means easier handling, simplified assembly and lower freight rates. Micore 160 board also has good sound control, reducing noise in open plan interiors.

Micore 
Mineral Fiber Board 160

Thickness 3/8 inch (.375)
Â½ inch (.500)
5/8 inch (.625)
Â¾ inch (.750)
Tolerances Thickness 0.015 inch  sanded and coated
Thermal Conductivity k Factor = .39
R Value (1/2 inch board) = 1.27


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## Kate1569 (Jan 21, 2011)

I agree with both of you. I ordered Micore 300 today, because it is stiffer, which is critical for tiles. It is important to understand, though, that it has a lower R value than Micore 160, contrary to what has occasionally been purported on this board. 

I wonder why, by the way, in their product description, they actually advertise the "high k-factor" of the Micore 300. Anybody buying this for insulation would see this as a minus. But maybe there are other applications where a higher k-factor is desirable.


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## billbaehr (Mar 2, 2011)

Micore 300 is slightly more dense than Micore 160.  As with all insulation, higher density means less air infused into that material and therefore not quite as good as an insulator.  

On the plus side, it is a bit more rigid (i.e. durable) and less likely to compress under weight than Micore 160.


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## pixalu (Feb 14, 2014)

Hoping to revive this thread with a question about Micore 300:

I'm contemplating buying some to make a temporary pad under a stove that doesn't currently have enough floor protection. If I do, I will put two layers of Micore 300 on top of an existing brick hearth, and then put the stove on top of that. I will not be tiling over the Micore, but I probably would put a sheet of 24 gauge steel on top of it.

Is the Micore durable enough to withstand the pressure of somewhat uneven bricks underneath, and the legs of the stove on top of it? Or would it need additional protection? I could put a sheet of 1/4" Durock underneath and/or on top of it, but I can't add more than another 1/2" of thickness because of space constraints. I could also put 1/2" steel plates under the stove legs, or something like that.

Any thoughts? I will have to order the Micore sight unseen and probably nonreturnable, so am hoping to leverage the collective experience here to decide.

Many thanks.


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## rwhite (Feb 14, 2014)

Can't speak to the 160 but Micore 300 is definately not strong enough to set a stove on. It needs to be sandwiched between 2 surfaces. I used 1/2" Wonderboard and tiled the top. I don't know the actual material it's made of but it's like working with compressed newspaper. You can break it off with your hands,


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## begreen (Feb 14, 2014)

Agreed. Micore is too soft to support a stove. I would add a layer of cement board. One layer of 1/2" micore 300 + 1/2" durock nexgen+ sheet metal will provide an protection of R=1.42.

What stove is this for pixalu?


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## pixalu (Feb 15, 2014)

That's what I was afraid of.

It's for an Englander 13-NC, needs R of 2 or more. I already have a layer of brick, which gives me 0.40-0.45--but I only have an inch of clearance above that to add 1.6, or I block the chimney cleanout door. Also it needs a big pad, 42" square...

I have pretty much shelved the idea for now. I had already planned on moving that stove to another location in a couple of years, and I may just do it now and get a different stove instead.


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## W.B. (Feb 15, 2014)

pixalu said:


> Hoping to revive this thread with a question about Micore 300:
> 
> I'm contemplating buying some to make a temporary pad under a stove that doesn't currently have enough floor protection. If I do, I will put two layers of Micore 300 on top of an existing brick hearth, and then put the stove on top of that. I will not be tiling over the Micore, but I probably would put a sheet of 24 gauge steel on top of it.
> 
> ...




Just get some thinset or mortar and skim coat the bricks before you put down the micore.  That should give you a flat surface to work with.


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