Insulating around fireplace flue

Michael Thomas

What is it venting? If it's a listed vent system, you would use the manufacturer's approved firestop and insulation shield, a typical example:

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Home Inspections, Infrared (Thermal Imaging) Leak Identification and Inspection Services, Roof, Attic, Building, Basement and Foundation Moisture Intrusion and Water Leak Inspections, Troubled Building Consultations - Serving Chicago and Suburbs
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Termite

There's no need to fuss too much about getting an insulation shield from the manufacturer....One can be easily made with a piece of duct metal and a few sheet metal screws or rivets. Wrap the metal LOOSELY around the vent and fasten the ends together to create a circle. Just don't attach to the vent.

If the fireplace is a woodburner I'd say minimum 2" of clearance is a good average. If it is a gas logs unit it'll usually require minimum 1" clearance. When in doubt be safe and get a couple inches of clearance.

Michael Thomas

Around hare, if it's listed system, and the manufacturer makes a listed firestop and/or insulation shield, most AHJs want to see the listed components, especially at manufactured fireplaces.

YMMV.

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Home Inspections, Infrared (Thermal Imaging) Leak Identification and Inspection Services, Roof, Attic, Building, Basement and Foundation Moisture Intrusion and Water Leak Inspections, Troubled Building Consultations - Serving Chicago and Suburbs
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BlueBSH

well after not getting to this project I finally got around to it...

cut out the drywall in the inside the house chase to get full access, which really showed me how tight they built this to the flue..

I could now see the codes on the flue pipe, it is heatalator SL flue pipe (double walled) 8" Inner diamater, and 10" Outter

I ran the fireplace at full heat for a while to see how much the pipe heated up, used an IR camera and it only got to about 80 degrees out the outside, which isn't bad considering the ambient temp was in the mid 70's.

I made a firestop coller out of sheet metal in two pieces and allowed them to overlap by a few inches, sealed it all up with red high tempature caulk (the fireproof kind)

I still have to make an insulation dam, but not sure if I have room or not considering they took the bare minimum clearances and there is no more room to cut or move

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House Information: Build 1996, 1500 sq ft basement, 1500 sq ft 1st floor, 800 sq ft 2nd floor, 560 sq ft unfinished attic space on 2nd floor. Insulation: Attic blown fiberglass, walls R-19, Basement R-19. HVAC: Trane xc95m fully modulating furnace, single zone, Trane XL20i commiunicating AC unit, TCONT900 Communicating thermostat.

akm

Similar situation, except will be trying to use oval (4" round equivalent) type-b flue pipe (for gas waterheater) up thru a 1-story (to get from basement to attic) exterior wall (gable-end, between 2x6 studs and insulation).
Should we provide a sheet metal 'chase' at min 1" clear of the flue pipe, in the wall framing, all the way (except at firestops) from basement to attic ?
Keeping it 1" clear (per local code) all the way up seems like a challenge, but I suppose with straps etc it could be done.
Or, is there another 'chase' material that could be used ?
Is there a good source (manual etc) for this type of installation ?
Thanks much for your help.

Windows on Wash

Best bet is to use sheetmetal and fireproof sealant to air seal the flue to the attic floor and build up a tall enough wall around it so that it does not get insulation piled up against it.

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