interior chimney--insulate liner inside chimney above the roof?

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rmcfall

Feeling the Heat
Hearth Supporter
Nov 28, 2005
308
I am going to be helping my father install a woodstove in the near future and he has a fireplace with an interior chimney. While I understand he doesn't NEED to insulate his liner because his chimney is on an interior wall, should the top portion of the liner be insulated where the chimney exits the roof?
 
I just installed a liner in an interior masonry chimney and insulated it the whole way. It improves draft and helps with creosote buildup! At least that is what I was told. I have to say it is working very well.

Craig
 
In a couple other installations, which were both with chimneys on exterior walls, I did insulate the liner to help with draft, etc. With an interior chimney, however, I don't know as though it will help with draft so much. Depending on the liner, I believe it may be necessary for the UL listing though.

MALogger said:
I just installed a liner in an interior masonry chimney and insulated it the whole way. It improves draft and helps with creosote buildup! At least that is what I was told. I have to say it is working very well.

Craig
 
MALogger said:
I just installed a liner in an interior masonry chimney and insulated it the whole way. It improves draft and helps with creosote buildup! At least that is what I was told. I have to say it is working very well.

Craig

Did you know what I saw today? I saw a home where there is a ladder with a roof hook left on the roof . I think now that's clever makes easy access to get up there for the anual cleaning and monthly observations. Makes for cleaning the termination cap a breeze.
 
rmcfall said:
I am going to be helping my father install a woodstove in the near future and he has a fireplace with an interior chimney. While I understand he doesn't NEED to insulate his liner because his chimney is on an interior wall, should the top portion of the liner be insulated where the chimney exits the roof?

Insulation on liners is a hot topic (pun intended) with much debate, especially on setups like yours.

Code wise, Elk can say it better, but if your existing chimney is NOT currently in good repair (NFPA 211 compliant) then it appears most liners need to have insulation in order to meet code per the strict interpretation.

Functionally, I don't think I've ever seen a case reported where it HURT the performance, and many cases where it helped. I would say the more insulation you can manage the better, it won't hurt and may help to both improve draft and reduce creosote buildup. The colder it is where you are at, the more it will help.

Physically, it might or might not be possible to do much insulation, depending on the sizes of the liner and the existing flue - If you are trying to put a 6" liner down an 8x8 clay tile liner, there basically isn't ROOM to get the insulation down there.

Whether you do insulation or not, but especially if you don't, it is VERY important that you seal the top and bottom of the flue so that you don't get air movement between the outside of the liner and the chimney.

Gooserider
 
rmcfall said:
I am going to be helping my father install a woodstove in the near future and he has a fireplace with an interior chimney. While I understand he doesn't NEED to insulate his liner because his chimney is on an interior wall, should the top portion of the liner be insulated where the chimney exits the roof?

I would definately insulate it above the roof. I have exterior masonry chimneys. I stuffed the top three feet of both with insulation right up to the liner cap. You can tell exactly where the insulation ends by looking at where the crap begins.
 
elkimmeg said:
MALogger said:
I just installed a liner in an interior masonry chimney and insulated it the whole way. It improves draft and helps with creosote buildup! At least that is what I was told. I have to say it is working very well.

Craig

Did you know what I saw today? I saw a home where there is a ladder with a roof hook left on the roof . I think now that's clever makes easy access to get up there for the anual cleaning and monthly observations. Makes for cleaning the termination cap a breeze.

Chicken ladders are very common in this state and many do leave them on the roof, as it does make things much easier if you are up there alot. Beats lugging it up each & every time. As long as they are made with good materials. Nothing worse than hoping on one that has rot, and you don't know it until you hear/feel it cracking apart.
 
I'd say for an additional couple hundred bucks, Insualte the whole thing and be done with it.
Better to do now, then have a draft problem and end up doing it after everything is hooked up.
 
elkimmeg said:
Did you know what I saw today? I saw a home where there is a ladder with a roof hook left on the roof . I think now that's clever makes easy access to get up there for the anual cleaning and monthly observations. Makes for cleaning the termination cap a breeze.
Hey that sounds like my house.

There is a ladder on the side of the house that leads up to the lower roof and a ladder on the lower roof that leads to the upper since the day of my install.

I hate the low slope on the lower roof for cleaning the gutters and crap that ends up hanging up up there all the time but I love it when it's time to go up for there any reason.

On the topic: I have a 50% interior 50% exterion chimney, and I insulated about 17 of the 18 1/2' ... it drafts great and I can easily start a fire when it's 60 degrees outside.
 
What are you guys using to insulate the liner? I have 4" pvp going through 8" pipe all the way up and out the chimney.
 
SoCal65 said:
What are you guys using to insulate the liner? I have 4" pvp going through 8" pipe all the way up and out the chimney.

SoCal, please note that pellet vent and liner do not have the same requirements as wood liners. You can use fiberglass insulation with your pellet stove but this wood unit should only use ceramic wool, vermiculite, or some other Type HT approved method.
 
rmcfall said:
I am going to be helping my father install a woodstove in the near future and he has a fireplace with an interior chimney. While I understand he doesn't NEED to insulate his liner because his chimney is on an interior wall, should the top portion of the liner be insulated where the chimney exits the roof?

Insulation IS NEEDED around your stainless steel liner in all NON-COMPLIANT masonry chimneys. Only if you have a code compliant chimney do you have a choice, regardless of the brand of liner. As has been pointed out here many times before no SS liner is approved for use with Non-compliant chimneys without insulation.

So, in this case, the location of the chimney is secondary. If non-compliant (which is very likely and should be assumed unless it can be confirmed by a competent chimney professional) you MUST use insulation. If the chimney is compliant (to NFPA 211 standards) then you can consider the location and the differences between inside chimneys and exterior chimneys.

I recommend you insulate. If you can afford it it does not make sense to skip the insulation.
 
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