Do i need an insulated liner

[bholler]

I was asked to start this thread due to a discussion in another thread.

I will start by posting the applicable code.

https://codes.iccsafe.org/public/document/IRC2015/chapter-10-chimneys-and-fireplaces

Code r1003.18 is the code regarding clearances of masonry chimneys. It says if you dont have the required clearances you need a liner listed to ul 1777 and rated for a chimney without the requred clearances.

There is no liner available that has that rating without insulation. And in my experience a very small percentage of chimneys out there have proper cleatances.

So my answer is in almost all cases yes you need insulation. And even if you dont need it by code it still offers lots of performance benifits. So even if you dont need it you still want it.

 

[Ctwoodtick]

For a new install or re-install, it’s very small added cost to have liner insulated. Safety is much increased in the event of a chimney fire. I went from uninsulated to an insulated liner and was shocked how much less buildup I got in liner when swept. The lesser buildup decreases likelihood of chimney fire. Double benefit.
Obviously all bets are off if you’re trying to burn wet wood.
It might be a good way to filter out bad contractors too. If they say you do not need insulation as a general rule, find a different installer who understands the need for it.

 

[fire_man]

Both my liners are insulated but I still can't imagine how my clay liner on the outside edge of a 6'x3' chimney could radiate enough heat during a chimney fire to catch the structure on fire. The liner is almost 3 feet from any wooden material.

But yes its insulated.

 

[bholler]

Both my liners are insulated but I still can't imagine how my clay liner on the outside edge of a 6'x3' chimney could radiate enough heat during a chimney fire to catch the structure on fire. The liner is almost 3 feet from any wooden material.

But yes its insulated.

I agree there should be a thickness of masonry over which you dont need that clearance. But there isnt and heat can travel through masonry pretty well.

 

[joshuaboston]

My question is...

Will an insulated liner help with a negative draft?

 

[bholler]

My question is...

Will an insulated liner help with a negative draft?

No. It will help establish draft faster. And it will make draft better and more consistent but it wont overcome negative pressure issues

 

[Poindexter]

So even if you don't need it you still want it.

Thank you.