Today's question open for discussion Liner Insulation?

[elkimmeg]

In the building industry claimes are made about products that do not always turn out to be time tested? Example Ice and water barrier, used for roof shingling. Made of ruber type compound that is suposed to seal nail penetrations, but after 6 year it looses the elasticity and the sealing. Huge debate on tyveck about breathability water resistant, VS tap paper being water proof Again over time tyveck looses some of its properties to water resistance.

The question is the longevity of liner insulation. What is the life expectancy? Does it break down and loose properties and what about time testing? A battle is going on in the insulation industry between alternative to fiber glass and poly and bubble wrap duct work. Each side if having the other's product tested. Did you know that foil faced insulation, looses it reflective ability in less than a year due to oxidation? Not just exposed insulation but behind walls? If reflectivity is lost what does't that mean for the r value? How would it apply to foil faced liner insulation? No I do not have the answers. I hoping debate will educate me. I do not not want to require installation of insulation, if it is not time tested and properties degrade over time. I want to understand its limitations

 

[rmcfall]

That's interesting. I spoke with a company the other day and asked whether I could use unfaced insulation with their liners. They told me that foil faced insulation was required because it reflects the heat back into the pipe. Seems to me the unfaced would be just fine, but I also thought I should follow the manufacturer's recommendation/requirement. That said, the unfaced is A LOT cheaper.....

 

[NFreiermuth]

Nice info elk.

I have seen the foil get that dusty oxidation on it (Aluminum Oxide???) I have always wondered if it would degrade the R-value over time.

Here's a question,

Have you seen sprayed in Poly-Urethane degrade over time.
I have seen it turn to dust in the Sun's UV rays, but how about crawl spaces???
Or does it outlast us???:coolsmile:

 

[HarryBack]

maybe shedding a little light here:

the loss of reflectivity doesnt alter at all the R value of the insulation. The foil was originally applied in an attempt to reflect heat back into the living space, irregardless of R value. By the way, it was very difficult to attain reflectivity with the product, because the surface had to be COMPLETELY flat, with a small airspace in between.
As for using it in the flue for insulation....NO! Its not solely a foil facing, rather a foil face mounted on kraft paper! Therefore, the foil facing is combustible and not the best choice for liner insulation.

 

[elkimmeg]

the poly side of insulation battle One when the r value is given for th from the poly industry it comes out higher than the equilvant fiberglass in a 2/4 wall. A closer look the poly fill is using or calculating its r-value for the full 4" and we all know a 2/4 is 3.5"
Fiberglass works but it needs to be installed properly something under attack from it opponents claim that it is not isltalled correctly leaving voids and effectively a reduced system r-value.

I have inspected about 5 new homes with poly fill I also noticed viods and bubling where it does not fill the entire cavity. I will say onething what a mess as excess is trimmed of witha hand saw. Really I thought it would flow better I know there is a difference in cost, ploy being more. Is it better depends on who's oppinion you listen to

 

[Turner-n-Burner]

As I understand it, the foil is for radiated heat, not conducted heat. The R value calculated for insulation material with a foil face is an "equivalent" R value to attempt to show the significance of the radiated heat loss that has been stopped. In actual use, the insulation value of the material can vary significantly depending on the application.

In general, the hotter the heat source, the more significant the radiant energy is.

That said, I don't think that the foil on the liner insulation is really there to stop heat loss. I think it's mostly a binder to keep the rock wool in place and in good condition. For one reason - to act properly for radiant heat, the foil would have to be INSIDE the insulation - not outside. After all, there aren't too many other corrosion resistant, and inexpensive flexible materials that you can put on a chimney that won't melt or burn!

I think the insulation is mostly to improve draft, and in the case of a chimney fire, provide a little extra margin of saftey relative to the heat inside the liner igniting surrounding materials. In the case of lining an existing chimney that is in good condition - it shouldn't be a factor.

I plan on insulating my liner - better draft is the reason.

I welcome any alternate opinions before I order it!

-Dan

 

[rmcfall]

I posted this link in another thread, but didn't get a response. Since this issue has come up again, I thought I'd try again as well...

http://www.anvilfire.com/sales/k_index.htm

The 1" blanket is not foil faced, but I believe the 1/2" blanket is. These are the same price, so I was tempted to go with the 1" just to have the extra thickness. However, I heard that the foil faced insulation may be required for liner insulations. To the contrary, in this thread there is a post that states the foil faced insulation should not be used in liner installations because of the issue of kraft paper. Would someone please clear this up? Pictures of liner insulation that I have seen online appear to be foil faced. Perhaps I am misunderstanding something here... can someone please clarify...

Is a foil faced high temperature blanket acceptable for a liner?

Is a non foil faced high temp blanket equally acceptable?

 

[elkimmeg]

We are talking about two different products. House insulation and liner insulation Unfaced liner insulation does not meet ul listings. As it stands now the liner insulation has to be foil faced Home /house does not.