Can I use Koawool?

[kniffin50]

I'd like to know if I can use Koawool to make a 'soft block off plate' for my fireplace insert?It has a Selkirk chimmney liner.
Thanks-Rusty

 

[oconnor]

Kaowool(edit - spelling corrected) (www.thermalceramics.com) is very thin (1/4 inch) so I'm not sure how it would work - that said, it is a porous fibre, so it wouldn't do well at keeping air from passing thru it. Kind of the same as trying to airseal around a window with fibreglass. It is also not something that you want to have exposd to your home air due to the very small fibres that can become airborne if disturbed - like many things out there, they are considered carcinogenic acording to the MSDS sheet.

Rockwool (trade name Roxul www.roxul.com) is a thicker product like fibreglass batts, but is not designed for exposure to the high flue temps that a liner will have. It is tested to 1382*F - your flue is tested to 2000 or 2100*F depending on Canadian or US spec - that said many folks have it installed above block off plates, or as a soft plate like you describe. Slightly less of a problem when airborne particles (not classified as carcinogenic to humans, only to animals). It is permiable to air, so makes a poor airseal.

Here is what the MSDS says about heating it: Primary combustion products of the cured urea extended phenolic formaldehyde binder, when heated above 390 °F (200 °C), are carbon monoxide, carbon dioxide, ammonia, water and trace amounts of formaldehyde. Other undetermined compounds could be released in trace quantities. Emission usually only occurs during the first heating. The released gases may be irritating to the eyes, nose and throat during initial heat-up. Use appropriate respirators (air supplied) particularly in tightly confined or poorly ventilated areas during initial heat-up.

Your flue will definately get above 200F. The off gassing will occur whenever a new portion of the material gets above the heat required.

In the end, I will be installing a metal block off plate. These two products cause me concerns (Kaowool - carcinogen if fibres get airborne, Roxul is not rated for flue temps, both are a poor airseal) when they are used as a block off plate.

 

[Adios Pantalones]

Kaowool. It's not just 1/4" thick- you can get it in 1", 1.5", 2" thick blanket material, or in board form. You can also add a silica or alumina stabilizer so that no fibers float around after install.

 

[kniffin50]

thank-you Oconner for that info.
Rusty
p.s. Ican spell it anway I want

 

[Rudyjr]

Brent, I believe there are different products for different applications with rockwool. The product that I used in my block off plate was listed as firestop insulation, no binders were listed, loosely compressed. The temperature range for this product was over 1800 degrees according to the insulation company that gave it to me. The rockwool listed in my McMaster Carr catalog was listed as duct insulation and was semi rigid board with a lower temp rating. Could this be the difference? Jim Melting point of batt insulation is listed at 2150 degrees (which is what I believe they gave me)

 

[Adios Pantalones]

thank-you Oconner for that info.
Rusty
p.s. Ican spell it anway I want

Sure you can, but when you google search for prices, you will have a few issues.

I was trying to help.

 

[kniffin50]

Iwas only kidding.
Rusty

 

[oconnor]

Brent, I believe there are different products for different applications with rockwool. The product that I used in my block off plate was listed as firestop insulation, no binders were listed, loosely compressed. The temperature range for this product was over 1800 degrees according to the insulation company that gave it to me. The rockwool listed in my McMaster Carr catalog was listed as duct insulation and was semi rigid board with a lower temp rating. Could this be the difference? Jim Melting point of batt insulation is listed at 2150 degrees (which is what I believe they gave me)

The MSDS sheet from Roxul covers all the Roxul products - obviously another manufacturer will have thier own MSDS sheet.

My main point is that rockwool is not meant to be exposed to 2100F all the time - it is meant to slow fire spread, not be exposed to 1200F for 20 years - even the pipe wrap that Roxul sells for industrial application states that there is an offgassing that occurs, and that ventilation is required on system startup and break-in. Another rockwool manufacturer may not have the same issues, but I haven't seen it yet.

(Edit - comment added) Melting point is one thing, but you can be sure that something happens before that temp which I don't want in my house - the flammability test is 1300ish - somewhere between 1300 and chimney fire (2100) is where the problem will occur, and I don't want extra problems should I have a chimney fire, like insulation that is installed around my liner that wasn't meant to be there.

In the end, whenever you use a product in a way that is different than what the manufacturer intended it, you need to do the research - Rockwool and Kaowool may work, but they have drawbacks (air leakage, off gassing, flammablility at 2100F). A sheet of steel has no drawback once it is installed - it isn't permeable to air, wont burn, wont cause airborne particles, and is cheaper than all of the above - the only drawback is cutting it - need tools - and sealing it - high temp silicone at the steel to brick edge and stove cement at the liner.

Sheet steel is a better material and less risk for the application at a cheaper price - why try to use someting else?

 

[Rudyjr]

I agree Brent, that is why I put a steel block off plate with rockwool above it. I am not a fan of insulation with nothing holding it in place and seperating it from the living space. My chimney sweep however stated that at least in our area it is common for installers to simply pack insulation around the pipe where it passes through the damper. I do not see how this can possibly pass an inspection but it must. Just one of the reasons I decided to install mine myself.

 

[BrotherBart]

My main point is that rockwool is not meant to be exposed to 2100F all the time - it is meant to slow fire spread, not be exposed to 1200F for 20 years...

If Roxul isn't acceptable, pray tell what is out there that is? What do ya think that insulation wrapped around a liner is made of?

 

[oconnor]

I agree Brent, that is why I put a steel block off plate with rockwool above it. I am not a fan of insulation with nothing holding it in place and seperating it from the living space. My chimney sweep however stated that at least in our area it is common for installers to simply pack insulation around the pipe where it passes through the damper. I do not see how this can possibly pass an inspection but it must. Just one of the reasons I decided to install mine myself.

I think the issue around common practice and inspections is that folks who do the work don't do enough research on what they are doing - I wouldn't even put the kaowool above a steel plate given the temp issues but lots do, and they have no problems - that is the exact rationale for some of the common practices that are well excepted - lots do and have no problems.

The issue is that these installs need to be able to deal with the abnormal conditions of a chimney fire and not cause issues - liner contains fire, insulation retains insulation properties, thermal transfer to adjoining structures doesn't affect thier durability.

The extra R14 of the kaowool above the steel plate does very little benifit - liner is 1200F on both side of the plate, so there is little thermal transfer up the flue - if anything, the transfer would be from the non-ventilated space (inside the flue, above the plate) to the ventilated space in the firebox - again, the kaowool seems to add little to no benefit, given that thermal tranfer is either neutral, or likely in favour of tranfer to the inside of the home vice up the flue.

 

[allhandsworking]

When I intalled my liner and block off plate it came with insulation that looks like fiberglass insulation. I wonder if it is? I dont see what all the fuss is about.

 

[oconnor]

My main point is that rockwool is not meant to be exposed to 2100F all the time - it is meant to slow fire spread, not be exposed to 1200F for 20 years...

If Roxul isn't acceptable, pray tell what is out there that is? What do ya think that insulation wrapped around a liner is made of?

I think - actually I know - that Kaowool made of kaolin, and is spec'd for continuous use above 2000 F - http://www.thermalceramics.com/pdfs-uploaded/datasheets/americas/514-205.pdf

And that rock wool is made from basalt rock and slag with added binders - as produced by Roxul as Rockboard 60, Enerwrap 80 etc - and is spec'd as follows:
ASTM E 136 Behaviour of Materials at 750°C (1382°F) - Non-Combustible
Maximum Service Temperature:
ASTM C 411 Hot Surface Performance In Compliance with ASTM C612 @ 1200°F(650°C)

You can check out the tech data sheets here - http://www.roxul.com/sw34975.asp?apptype=74 . I looked thru most of them, and they all have a max service temp of 1200*F

The residential insulation batts do not state a Max service temp - as the wood studs would burn before the insulation, but I doubt they are higher than the service temp of the above products, which are marketed for the needs of furnaces and high temp ovens.

Just cause lots of folks use it doesn't mean it was designed for use around a liner.

You need to think - What does it do in a chimney fire?. If you are happy, then go ahead. Free country - and I'm free to read up on it and decide that it wasn't built to use around a liner.

I have not looked at all rockwool brands - so if someone knows one that is better than Roxul, let me and the rest of us know.

 

[oconnor]

When I intalled my liner and block off plate it came with insulation that looks like fiberglass insulation. I wonder if it is? I dont see what all the fuss is about.

Whatever it was, it should have come with instructions and some ULC/CAN label. The kaowool stuff is fine for liners - 2000*F continous. I'm not convinced mineral wool belongs near a liner.

The fuss is about having a smoking smoldering mess around your liner during a chimney fire if you use the wrong stuff.

 

[karl]

They Sell a 'paint' like substance, that you put on the stuff, that makes it rigid.

 

[burr]

Properly installed, tight fitting common sheetrock is better fire protection than ceramic fiber insulation in most instances, check stairwell codes. It's much cheaper (product and installation) AND has longer protection times when UL tested. And it is never mention here. Ceramic fiber is a high temp insulation, used for protecting against heat, or holding and using heat, not especially fire protection, although the manufacturer has attempted to market such a product.

To answer the question, you can use Kaowool for high temp insulation, but fire protection is not its' primary or best application.

 

[Rudyjr]

Brent you are using the specs for a different product : And that rock wool is made from basalt rock and slag with added binders - as produced by Roxul as Rockboard 60, Enerwrap 80 etc - and is spec’d as follows:
ASTM E 136 Behaviour of Materials at 750°C (1382°F) - Non-Combustible
Maximum Service Temperature:
ASTM C 411 Hot Surface Performance In Compliance with ASTM C612 @ 1200°F(650°C)

This as I said before is a board and a wrap which has added binders to retain its shape. Firesafe is rockwool that has a melting point of 2150 degrees . This is the spec sheet for unfaced the temperature range changes for faced and anything made into a board because of the binders. It states the temperature tested at and the melting point. I do not think by looking at this spec sheet that you could have a smoldering mess but it could melt at 2150 and above.http://www.roxul.com/graphics/RX-NA/Canada/Product Literature/Tech Data/RoxulSafe-7-3-08.pdf
In my case with an exterior chimney and basement installation there is quite a temperature difference on the two sides of the blockoff when the stove is not in use. Seems to help mostly with condensation when the stove is sitting idle and there is temperature fluctuations. It was in the single digits here last weekend and today it is almost 70.

 

[burr]

Properly installed, tight fitting common sheetrock is better fire protection than ceramic fiber insulation in most instances, check stairwell codes. It's much cheaper (product and installation) AND has longer protection times when UL tested. And it is never mention here. Ceramic fiber is a high temp insulation, used for protecting against heat, or holding and using heat, not especially fire protection, although the manufacturer has attempted to market such a product.

To answer the question, you can use Kaowool for high temp insulation, but fire protection is not its' primary or best application.

When properly installed, and in practical applications, ceramic fiber or mineral wool is ideal for insulatiion and protecting from heat. And if any applications approach melting point, you've got the wrong product. The problem with ceramic fiber or mineral wool in a chimney wrap is the single layer. Although these products should not actually melt, they WILL SHRINK, producing air gaps. This is not acceptable in fire protection. I'm not talking about great shrinkage, but any shrinkage, and any air allowed will fan the flames, not smother them.

In proper application, ceramic fiber is layered with offsetting joints, so that any shrinkage will not allow for direct hotspots.

 

[rickw]

I think you're better off with a steel block-off plate. Not too hard to do; especially if you have access to sheet metal brake and shear. Check the wiki on this site. Have ordered a big bag of perlite to pour around the liner from the top for insulation.

Unless you're willing to do it yourself there might be a problem; I couldn't get any of 3 shops to even admit that it might be a good thing much less quote the job. Best of luck!

 

[oconnor]

Brent you are using the specs for a different product : And that rock wool is made from basalt rock and slag with added binders - as produced by Roxul as Rockboard 60, Enerwrap 80 etc - and is spec’d as follows:
ASTM E 136 Behaviour of Materials at 750°C (1382°F) - Non-Combustible
Maximum Service Temperature:
ASTM C 411 Hot Surface Performance In Compliance with ASTM C612 @ 1200°F(650°C)

This as I said before is a board and a wrap which has added binders to retain its shape. Firesafe is rockwool that has a melting point of 2150 degrees . This is the spec sheet for unfaced the temperature range changes for faced and anything made into a board because of the binders. It states the temperature tested at and the melting point. I do not think by looking at this spec sheet that you could have a smoldering mess but it could melt at 2150 and above.http://www.roxul.com/graphics/RX-NA/Canada/Product Literature/Tech Data/RoxulSafe-7-3-08.pdf
In my case with an exterior chimney and basement installation there is quite a temperature difference on the two sides of the blockoff when the stove is not in use. Seems to help mostly with condensation when the stove is sitting idle and there is temperature fluctuations. It was in the single digits here last weekend and today it is almost 70.

Rudyjr

The details on that spec sheet are the same as for the Safe and Sound and Flexibatt - both of which aren't meant to be exposed to heat during thier use, but are used to create firestops. The items I mentioned earlier actually mention a high heat application, but not high enough for use around a liner. When it comes to materials like these, if they don't say you can use it in a given situation, then they haven't tested it. I'm sure if you called them and enquired as to the suitability of exposing the product to 24/7 duration of temps of 1000-1200 F, they wouldn't recommend it.

Burr

Your info is correct, but you've missed the point of a block off plate - it is to prevent convective air circulation. The OP was inquiring about using either Kaowool or rockwool as a "soft" block off plate. In the end, given that both are permeable to air, and rockwool won't stand the temp of the liner, neither is going to do as good a job as a piece of sheet steel.

All
I find it amazing that we will flinch over K values in hearth pads and inches in clearances to combustibles like mantles, but we will use things like rockwool, which I have never seen rated for constant exposure to liner temps, just because we think it won't burn. If you never have an overtemp/chimney fire, you will be fine. But what if you do?

 

[Rudyjr]

Brent your numbers are nowhere to be found on that spec sheet. 2150 melting point and a test point are all that are given.The fact that it meets a certain spec does not mean that it is the max it is rated for. I don't know what the specs for Canada are but there has to be some reason why they allow this in the states. This is the product they use with fireplace doors and manufactured block off plates. If it melts at 2150 that is one thing, it does not burn or support combustion.
Quote: I’m sure if you called them and enquired as to the suitability of exposing the product to 24/7 duration of temps of 1000-1200 F, they wouldn’t recommend it.
It is in fact tested to 1382 degrees f and the flamability and sread are listed as 0
A chimney fire is approx 2000 degrees, the melting point is listed as 2150 degrees,flamability is 0 spread is 0 in my masonry chimney I believe that the weakest link would be the galvanized sheet metal block off plate and the high temp silicone caulk.

 

[oconnor]

Rudyjr

The numbers aren't on the spec sheet because they aren't tested to it. If you look at their high heat products, from the US site, they specify a maximum temp when it is available, and none are above 1200F, let alone 1382F. As you work your way down the spec sheets, they drop the temp to 1200F, and then they drop a maximum service temp all together. The 1382F number is for a burn thru test, and doesn't mean it is stable for ever at that or any other temp. It means. It comes from ASTM E136 - and assumes that when exposed to 1382F for 30mins, that temp rise of protected items is not excessive (numbers can be looked up), and that the mass of the product doesn't decrease by more than 50%. If the stuff around my liner meets that spec, then 30 mins into an overfire, I may have only half the insulation left - not suitable. When they give a max service temp, that is the temp they feel it to be stable forever at.

You just can't assume that the statement that rockwool melts at 2150F means you can use it anywhere - that same statment is on every spec sheet that they produce. It is a general statement about mineral wool, not a spec for any given product.

As for fireplace doors, I have no idea what they use - saying they use it doesn't mean it is so, - but, I have found nowhere that rockwool can be exposed to temps above 1200F safely. The lack of a stated maximum temp does not imply that the 2150F general statement is what you can go by. The stuff Roxul makes for insulating furnaces has a stated max service temp of 1200F. If you download the catalogue - http://www.roxul.com/graphics/RX-NA/Canada/Product Literature/NA_ICI_Catalogue_06-08-07.pdf - you can run thru the whole lineup, and see that when it is meant for constant heat exposure, they state a temp. When it is not the intent of the product - no max temp, just the 2150F number.

Let's let logic and research prevail here, not common practice - we all know that common practice often doesn't meet code, or common sense - use a product that actually says it is good around a liner. Liner insulation systems are tested to 2000F (US) or 2100F (Can) temps for 30-60 minutes, depending again on US or Canada (again, exact details on the specs for flue gas products can be looked up). If the product doesn't pass these parameters, then it does not belong anywhere it can touch a chimney liner.

 

[Rudyjr]

Brent , Like I said I have a liner that is in sound shape the purpose for which I insulated the block off plate is as I stated. The practice right or wrong in my area is to pack insulation around the damper with no plate, which I did not do. I know that many installers in our area probably stuff ordinary fibergalss around them.I have spoken to one of the largest commercial insulation contractors in central Ohio and they stated that this product is commonly used around flue pipes. I installed it in my chimney above a galvanized block off plate.You need to re-read the spec sheet it says tested to 1382 f 2150 f melting point. If my masonry chimney were ever to exceed 2100 degrees i would certainly have bigger problems than this stuff melting.


General Product Information:
Description & Common Applications:
ROXUL® products are mineral wool fibre insulations made
from basalt rock and slag. This combination results in a noncombustible
product with a melting point of approximately
2150°F (1177°C), which gives it excellent fire resistance
properties. ROXUL mineral wool is a water repellent yet
vapour permeable material.
ROXUL

 

[BrotherBart]

I hear ya rudy. Both of my chimneys are packed for five feet with Roxul up top and the block off plate in the fireplace is too as is the pipe in the clay thimble in the basement. The walls next to the fireplace will burn before that stuff does as will the concrete blocks surrounding the thimble in the basement. I proved it with a torch before installation.

That chit will not burn. And nothing even smelled bad during the testing. It is nasty to work with but it ain't gonna burn. The stove and stainless pipe will be in a puddle before that stuff even breaks a sweat.

I have never said this in almost 8,000 posts but o'conner ya have this one wrong.

 

[oconnor]

I am afraid that I have yet to hear any information that answers the questions I have raised to either of you.

My assertions are this - The quoted 2150F is a general description, not a tested application - my logic - it is on all Roxul products, but those designed for high heat use have a specific Max Service temp listed - therefore, they did no testing on the other products other than ASTM E 136, which is not a service temp test, but a fire stop test.

1 - why, if the stuff only melts at 2150F, does only the industrial stuff meant for high heat applications have a max service temp of 1200F listed?
2 - why do you assert that the ASTM E 136 test means it can be employed at the 1382F temp when the test is for burn thru, not for service suitability?
3 - why do you assert that a product only tested to 1382F can be used in an application where the UL1777/CAN635 test uses 2000F (US) or 2100F (Can)?
4 - why do you believe that insulating a block off plate is even needed in the first place, when the heat tranfer based on temp differential inside the brick chase compared to the fireplace behind the stove is at best neutral, or more likely in favor of heat moving from the space that is sealed and heated by 15-30 feet of stainless pipe @800-1200F into the firebox, that is vented and air cooled?
5 - even if it would cause no problems until at least 2150F, why do you feel a product not tested to the UL1777/CAN635 spec is suitable for use around a liner?

Please don't let the fact that you have/have not done yours using this product influence your answers. Mine has the same soft plate installed, and I have come to believe it is a bad idea.

Answer these 5 questions for me if you would. There may well be something I am missing, and I am willing to learn.