DIY Chimney Liner Insulation -Leftover Roxul

[Brep]

I have a ton of Roxul left over from a damper block plate insulation installation and thinking about using that leftover Roxul to insulate the 5.5" liner ill be putting in with my wood insert.

Can I wrap the liner with 1/2 in Roxul, wrap with Roxul with stainless wire to hold in place and then cover with heavy duty high heat foil tape? Seems like it is the same but Significanlty less $ than the $250+ charged for a wrap blanket. $25 for tape and wire beats $250+ Given I have leftover Roxul, right?

What am missing?

 

[JA600L]

Technically you can't because it is not an approved chimney liner insulation. However, many people use it in contact with their liner and never have an issue.

 

[bholler]

It has not been tested and approved as insulation for liners. We do not know how well it will perform and protect your house in case of a fire. And it does not meet the ul listing or code.

 

[Brep]

Thanks for the insight on code and I completely understand. A little confused as there are numerous forums strongly advocating the use of block plates with Roxul. Surely some of the Roxul would touch the liner at a closer point to the firebox (where it should be the hottest). It is more about common sense than the money. Roxul has the same heat rating as the thermal wrap blankets, just not the certification (who knows how much the certification would cost given current EPAand Consumer Protection agencies).

I am not trying to agitate, just trying to rationalize. I might get the obligatory, "well just do it", but really trying to understand the pros and cons.

Exterior chimney lined in terra cotta, 8x13 with a 25' run using a 5.5" single wall 316l liner.

 

[JA600L]

https://www.hearth.com/talk/threads/can-i-stuff-roxul-up-the-chimney.94772/

 

[bholler]

Thanks for the insight on code and I completely understand. A little confused as there are numerous forums strongly advocating the use of block plates with Roxul. Surely some of the Roxul would touch the liner at a closer point to the firebox (where it should be the hottest). It is more about common sense than the money. Roxul has the same heat rating as the thermal wrap blankets, just not the certification (who knows how much the certification would cost given current EPAand Consumer Protection agencies).

Yes the temp rating is high enough. There is a lot more to it than that. That insulation needs to be able to keep the temps down on the outside of the masonry structure enough to keep any adjacent combustibles from catching fire. It may do that it may not we just don't know.

 

[ccmac]

If you do it the Roxul will fall apart, the wire just won't be enough to hold it onto the liner. Instead, purchase some stainless screen (it's fairly cheap) and then use a spray on adhesive, fold your Roxul over the liner then wrap the whole thing in screen, then wire tie it every 18in. maybe more often if it doesn't hold together well. This would work pretty well and maintain some durability and longevity. I would still recommend buying the insulation because the cost just isn't enough to justify this. Good luck and let us know how you do it.

 

[bholler]

I would still recommend buying the insulation because the cost just isn't enough to justify this.

And no matter what you do with the roxul you will never know if its properties are correct to protect your house in the event of a chimney fire. The stuff that is listed to use has been tested for that.

 

[JA600L]

I'm not advocating for anybody to go against code. However, there is no argument that it would not work. You just "shouldn't do it. "

 

[bholler]

I'm not advocating for anybody to go against code. However, there is no argument that it would not work. You just "shouldn't do it. "

There also is no info saying that it will work properly only info that it will not burn.

 

[Dmitry]

It is going to be a challenge to work with roxul. It breaks apart when bended and crumbles all over. It might bend a little , but not around 6' liner.

 

[volunbeer]

Impressive video - we put Roxul in the wall that will be tiled for our install here next month. I have enough left over to get in the crawlspace and lay it down around the stove pipe as it comes out of the ceiling and goes to the roof. I wanted something that was fire resistant (just in case) and dampened noise since our bedroom is on the other side of it.

 

[bholler]

I have enough left over to get in the crawlspace and lay it down around the stove pipe as it comes out of the ceiling and goes to the roof.

I hope you mean chimney pipe not stove pipe.

 

[begreen]

There should be an attic insulation shield around the chimney pipe in an attic.

 

[mellow]

Exterior chimney lined in terra cotta, 8x13 with a 25' run using a 5.5" single wall 316l liner.

I don't see how you could wrap Roxul around it and still fit it down the chimney unless you compress the heck out of it with the chicken wire.

Just pony up the extra cash and get the foil wrapped 1/2" insulation.