Micore 300 as chimney chase insulation?

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NVHunter

NVHunter

Feeling the Heat
Nov 3, 2013
292
Reno, NV
Can you use Micore 300 as chimney chase insulation? I know it's probably over kill but I just want piece of mind with lining the interior of my chase with something like micore.

What do you guys think? Yes or no? I'd need about 75 square feet of it to line the interior of the chase.

Thanks
 
I would use cement board instead of drywall with roxul for insulation if you are concerned.
 
My main concern is to keep heat off of the wood studs and OSB sheathing. I will be meeting the class a chimney clearances of course, just want something extra which will keep the heat off of the skeleton of the chase.

Would micore keep the heat off the wood structure? How about Duroc? I don't necessarily need to insulate the chase to keep it warm, or for code per my building department.
 
I dunno. Anything you can do to keep the chimney warmer is a good thing I would guess..for sure if it's a cat and you're doing a lot of low burns .
 
If the chimney pipe manufacturer's documented minimum clearance to combustibles weren't safe (with a non-trivial safety factor figured in), and verified by lab testing...it wouldn't be the manufacturer's minimum required clearance to combustibles. Rick
 
I guess I could put some roxul behind the micore or Duroc when I line the chase just to add to the insulation factor and keep the chase warmer.

I'm looking at running a cape cod under this system.
 
fossil said:
If the chimney pipe manufacturer's documented minimum clearance to combustibles weren't safe (with a non-trivial safety factor figured in), and verified by lab testing...it wouldn't be the manufacturer's minimum required clearance to combustibles. Rick
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I get it, as long as I meet the clearance requirements I will be fine. I'm just paranoid I guess and want a little extra assurance. Make me sleep better I guess.

Thanks
 
NVHunter said:
Can you use Micore 300 as chimney chase insulation? I know it's probably over kill but I just want piece of mind with lining the interior of my chase with something like micore.

What do you guys think? Yes or no? I'd need about 75 square feet of it to line the interior of the chase.

Thanks
Click to expand...

NVHunter:

Having used Micore 300, I would recommend that you not use it for insulating your chimney chase. I'm assuming that you are using a Class A chimney that has a 2 inch clearance to combustibles requirement.

The thing about Micore 300, it's not a very good construction material, especially used in a vertical orientation. Micore 300 is fairly friable, much more fragile than SheetRock, for example. Micore 300 has the consistency, more or less, of the overhead panels used with suspended ceilings. I used it in a horizontal orientation, as part of hearth insulation, and for that purpose it was fine. I agree with begreen on this issue - ROXUL batts would be perfect. And since ROXUL is non-combustible, you could put it up against Class A pipe as an insulator.

I suggest that you frame up the chase with 2X4's, drop the Class A down the chase, then stuff the ROXUL around the Class A. The ROXUL could be held in place with wire, or with high-temp tape used for sealing heating appliances. Then sheath over the framing with plywood, cement board, or OSB. The nice thing about ROXUL is that it is impervious to water.

Good luck with your install
 
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Ok I briefly looked into roxul and I found roxul rockboard 40-80. It comes in 1" through 4" thicknesses.

Sounds like a 1" sheet of this would be my ticket. What do you think? Has the same protective properties of roxul batts just ridged and I can line the chase interior with for added fire resistance.
 
Ok, I looked for rockboard in 1" thickness and couldn't find it online.

I stumbled across this product which is sold at home depot. Does anyone have experience with it?

It has a better R value than the micore does and is easy to work with it looks like.

Has a Class A fire rating too

http://www.bondedlogic.com/pdf/radiant-barrier/radiant-barrier-spec-sheet.pdf

I could secure one or two sheets of this and call it good. What do you guys think?
 
why not just use regular insulation as long as you are following the clearance requirements of the chimney and the appliance you can use what ever insulation you prefer it doesn't need to be non combustible. Also read the clearance requirements of your zc unit some of them require a certain open space above not just a clearance to combustibles. Follow all the clearances carefully and use what ever insulation you prefer
 
I'm installing a free standing stove in an alcove with the chimney exiting out the roof of the alcove and up the side of the house. This is why I'm building a chase (because the HOA doesn't want a shiny pipe up the side of the house to be visible.)

I guess I'm seeing anything will work per everyone's input.

Thanks
 
Oh ok I see then yes anything should work but I don't see why the chase would need insulated at all in that situation.
 
NVHunter said:
I get it, as long as I meet the clearance requirements I will be fine. I'm just paranoid I guess and want a little extra assurance. Make me sleep better I guess.

Thanks
Click to expand...

This is the only reason as stated above....

This is a completely new install and I'm a little paranoid... Don't want to burn the house down. Overly cautious I guess you could say.

Thanks
 
NVHunter said:
Ok, I looked for rockboard in 1" thickness and couldn't find it online.

I stumbled across this product which is sold at home depot. Does anyone have experience with it?

It has a better R value than the micore does and is easy to work with it looks like.

Has a Class A fire rating too

http://www.bondedlogic.com/pdf/radiant-barrier/radiant-barrier-spec-sheet.pdf

I could secure one or two sheets of this and call it good. What do you guys think?
Click to expand...

NVHunter:

I found this at a Home Depot site: http://www.homedepot.ca/product/rox...eathing-board-for-basement-and-exterio/995375

So it might be possible to special order this ROXUL product from a HD outlet. It's called: Roxul R6 ComfortBoard IS Insulated Sheathing Board for Basement and Exterior Wall Applications

It's 1.5 inches thick, 24"' wide by 48 "' long. I think that you could use the ROXUL ComfortBoard (semi-rigid) or the ROXUL flexible batts. Were it me, I would go with the batts because of the construction issues. That is, visualizing what you want to accomplish, stuffing the batts around the pipe would be easier than fastening any semi-rigid material/product to the studs.

The material you are proposing to use as an alternative is: "UltraTouchTM Natural Cotton Radiant Barrier is a lightweight, foil faced, fire retardant blanket-type insulation with multiple uses. UltraTouch offers excellent thermal and acoustical performance and carries a Class-A fire rating." This product is not a sheet, but a "wrap around" type insulation. I think it would be a bit more troublesome to use than the ROXUL options. "UltraTouch" would be OK to use in your proposed application because of its fire rating, I think, but it would not be superior to ROXUL.

As I mentioned earlier, ROXUL has one property that makes it very attractive for use with an "exterior" application: it's impervious to water. As you know, ordinary Corning fiberglass becomes a soggy mess should it ever get wet.

Is any insulation necessary for an exterior chase? No. But were I doing it, I would probably add the insulation as you are proposing "just because." After all, what's adding the insulation gonna hurt? Nothing.

 
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Eaglecraft said:
NVHunter:

I found this at a Home Depot site: http://www.homedepot.ca/product/rox...eathing-board-for-basement-and-exterio/995375

So it might be possible to special order this ROXUL product from a HD outlet. It's called: Roxul R6 ComfortBoard IS Insulated Sheathing Board for Basement and Exterior Wall Applications

It's 1.5 inches thick, 24"' wide by 48 "' long. I think that you could use the ROXUL ComfortBoard (semi-rigid) or the ROXUL flexible batts. Were it me, I would go with the batts because of the construction issues. That is, visualizing what you want to accomplish, stuffing the batts around the pipe would be easier than fastening any semi-rigid material/product to the studs.

The material you are proposing to use as an alternative is: "UltraTouchTM Natural Cotton Radiant Barrier is a lightweight, foil faced, fire retardant blanket-type insulation with multiple uses. UltraTouch offers excellent thermal and acoustical performance and carries a Class-A fire rating." This product is not a sheet, but a "wrap around" type insulation. I think it would be a bit more troublesome to use than the ROXUL options. "UltraTouch" would be OK to use in your proposed application because of its fire rating, I think, but it would not be superior to ROXUL.

As I mentioned earlier, ROXUL has one property that makes it very attractive for use with an "exterior" application: it's impervious to water. As you know, ordinary Corning fiberglass becomes a soggy mess should it ever get wet.

Is any insulation necessary for an exterior chase? No. But were I doing it, I would probably add the insulation as you are proposing "just because." After all, what's adding the insulation gonna hurt? Nothing.
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Thank you for the response. I'll look into this. Again thanks to everyone for their input on this.
 
For peace of mind safety I would put up Durock NexGen and call it a day. That will create an insulated fire barrier around the class A pipe. You don't want to super-insulate the chase or the studding will be exposed to high temps over a sustained period of time. That could lead to pyrolysis issues later on.
 
That's
begreen said:
For peace of mind safety I would put up Durock NexGen and call it a day. That will create an insulated fire barrier around the class A pipe. You don't want to super-insulate the chase or the studding will be exposed to high temps over a sustained period of time. That could lead to pyrolysis issues later on.
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That's exactly what I'm trying to avoid is pyrolysis.

I want to keep the heat away from the wooden structure of the chase and house. The chase will be vented on the top obviously so the heat can escape. I just want to put a material (micore, roxul, ultratouch, or Duroc) between the chase structure and the chimney pipe to minimize the heat the wood is exposed too.

Not wanting or truly worried about it being insulated just want to minimize the heat exposure to the wood structure.

I've heard Duroc won't be a good barrier as it allows heat to penetrate it (lower R value) and over time pyrolysis could take place.

So even the ultratouch fire barrier material would stop the heat from reaching the wood as it has a good R value.

Nothing major here to do....
 
Eaglecraft said:
NVHunter:

snip ... I agree with begreen on this issue - ROXUL batts would be perfect. And since ROXUL is non-combustible, you could put it up against Class A pipe as an insulator.

I suggest that you frame up the chase with 2X4's, drop the Class A down the chase, then stuff the ROXUL around the Class A. The ROXUL could be held in place with wire, or with high-temp tape used for sealing heating appliances. Then sheath over the framing with plywood, cement board, or OSB. The nice thing about ROXUL is that it is impervious to water.

Good luck with your install
Click to expand...

I'm not sure Begreen was implying you should wrap the Class A with Roxul. I haven't yet seen Class A instructions that don't require an air gap around the chimney inside the chase.

The Class A would be more likely to over heat and damage could result if it was covered with insulation, even non-combustible Roxul.

Check the instructions and read the clearances carefully. Sometimes its distance to combustibles, and some times its an air gap. For Class A, it's very likely an air gap.
 
No, I knew what he was saying. You never rap a factory made chimney. It needs the clearances listed, no matter what the material is (non-combustible roxul or what).

I emailed the company that makes ultratouch products and they say it's a no go with their product with chimney setups.

I really want a 1" thick piece of material or less (1/2" to 1" max). Does anyone know if Roxul is made in 1" thick pieces?

The chase doesn't have a ton of space in it as is. Don't want to be dropping down to the pipes minimum clearances here with thick material....
 
Air is a good insulator. Don't wrap the class A pipe with anything. It is already internally insulated. I am pretty sure that wrapping the pipe with insulation will void the warranty. Call the mfg. to confirm.

1/2" Durock NexGen has an R value of .39, which is decent and will protect the wood. If the chase is ventilated and clearances are honored or exceeded, then you have done plenty to ensure safety. To be honest in 8 yrs of being here I don't ever recall hearing of a fire in the chase, and only once do I recall a scary situation and that one had chase wood right up against pipe and fireplace.
 
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begreen said:
Air is a good insulator. Don't wrap the class A pipe with anything. It is already internally insulated. I am pretty sure that wrapping the pipe with insulation will void the warranty. Call the mfg. to confirm.

1/2" Durock NexGen has an R value of .39, which is decent and will protect the wood. If the chase is ventilated and clearances are honored or exceeded, then you have done plenty to ensure safety. To be honest in 8 yrs of being here I don't ever recall hearing of a fire in the chase, and only once do I recall a scary situation and that one had chase wood right up against pipe and fireplace.
Click to expand...


Thanks for all the help begreen. That sounds like what I'm most likely going to do. Use 1/2" Duroc and call it good.

I think (and tend to do this with everything) I've over thought this.

The interior of the chase will have these clearances from the studs; 3 1/2" on north/south sides of the chimney pipe and 11" on the east/west sides of the chimney pipe.

3" and 10 1/2" after the Duroc is installed.

The north south sides are my only concern but I'm still exceeding the 2" requirement.

Should be fine correct?
 
Yes, that all sounds good and beyond spec. Remember to put in a firestop if the chase is 2 story.
 
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Ok, thanks. It's only a one story chase but I'll see what the building department wants as they have the final say.

Thanks again.
 
"1/2" Duroc and call it good" Durock can be used by itself for the front facing or backing for tile, etc. But the technical department for US Gypsum (USG) brand of "Durock" specifically told me that I can't use Durock board by itself as a heat protective product in a chase wall due to it not having a significant R-value.

It's R-value of .49 per inch would have to be 8" thick to equal 1" of mineral wool. As such the manufacturer recommends using an insulation board or other product behind it. That's why they rate it only for 200F max, because the framing behind it can get hot even though the Durock itself is fairly fireproof.

You'd have a durable, very heat tolerant assembly using Durock over Mineral wool board.
 
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