fireplace chimney clearance

Cory Bates · 10-28-2014, 07:22 AM

I found this yesterday and i am unsure if the clearance is acceptable. This is for a freestanding fireplace.
What are your opinions? please educate me.

DSCN5150.jpg

**Nicky DeBolt** · 10-28-2014, 09:01 AM

Originally Posted by Cory Bates

I found this yesterday and i am unsure if the clearance is acceptable. This is for a freestanding fireplace.
What are your opinions? please educate me.

DSCN5150.jpg

Hey Corey,

Just using a the general clearance of gas fired heating equipment... it can range from 6" to 36", depending on manufacturer recommendation and type of equipment.

**Scott Patterson** · 10-28-2014, 09:39 AM

Is that the flue pipe coming up into the attic? Clearances will also be dependent on the type of flue pipe. Many times the clearance is embossed on the pipe. Also if that cone/thimble is part of the fireblock, it is wrong...

**Jerry Peck** · 10-28-2014, 09:58 AM

In addition to the previous comments - the following "typically" applies:
- single wall vent requires minimum 6" clearance to combustible material and insulation ... and ... is not permitted to go through an attic.
- Type B gas vent requires minimum 1" clearance to combustible material and insulation ... and, presuming they did not run single wall through the attic that is likely a Type B gas vent.

Several presumptions made above in that they didn't do it all totally wrong ... however, there is so much wrong in the photo that they may have done it all wrong.

**Mark Reinmiller** · 10-28-2014, 04:40 PM

Looks too big to be a B-vent. Double wall chimney for wood typically requires 2 inches of clearance. I know of nothing that allows no clearance. Also, there is no fire-stopping. That cone thing does not belong there (it may be a storm collar, but could just be some idiots attempt at fire-stopping. Of course, maybe this is some new piece of equipment that I never saw before, but probably not.

**Jerry Peck** · 10-28-2014, 06:18 PM

Originally Posted by Cory Bates

I found this yesterday and i am unsure if the clearance is acceptable. This is for a freestanding fireplace.
What are your opinions? please educate me.

For Mark, others, and myself - is this a gas fireplace, a wood burning fireplace, or ???

As Mark pointed out, the fuel being burned makes a difference in chimney/vent and clearances.

**Bob Harper** · 10-28-2014, 08:16 PM

This is probably a site fabricated attic insulation shield. The firestop should be on top of the ceiling joists in the attic but keeping insulation off the chimney is a good thing. As in all cases, find the rating plate and record the make, model, serial number, fuel, listing, and date of mfr. On the vent/chimney, find a listing sticker and take a pic. Also take pics of the vent termination, which can often tell the mfr.

Any pics from farther back showing the pipe above this storm collar?

**Stephen Tilleux** · 11-03-2014, 11:28 AM

A better picture would be good. That said it looks like a attic radation shield with a storm collar to keep insulation, mice etc out of the clearance area.

We install many attic radation shields with every current brand of gas vent and wood chimney's too. A storm collar added on top is sop and required in many cases by Mfg.

"This is probably a site fabricated attic insulation shield. The firestop should be on top of the ceiling joists in the attic but keeping insulation off the chimney is a good thing."
With a attic situation, the combo firestop radation shield installs under the celing and projects up through the joists and insulation. With plywood sheeting in a chase firestop on top is normal. This is outlined in the instructions.

That said I can not tell what brand or type of vent/chimney op has there.

**Mark Reinmiller** · 11-03-2014, 07:24 PM

I did not look at the photo closely when I replied. I see now that the actual chimney or vent would be quite a bit smaller than than sleeve that is visible. It makes sense that that would be an insulation shield, and I suppose a top like that would also make sense to keep insulation out, but I have never seen a setup like that. I still cannot tell whether there is proper fire-stopping.

**Ray Cole** · 11-17-2014, 02:41 PM

Originally Posted by Nicky DeBolt

Hey Corey,

Just using a the general clearance of gas fired heating equipment... it can range from 6" to 36", depending on manufacturer recommendation and type of equipment.

IFG G2426.4 Insulated sheild. Where vents pass through insulated assemblies, an insulation shield costucted of steel having a minimum thickness of 0.0187 inch (26 gage) shall be installed to provide a clearance between the vent and the insulation material. THe clearance shall not be less than the clearance shall not be lesss than the clearance to combustibles specified by the vent manufactuer's installation instruction. Where vents pass throug attic space, the shield shall terminate not less than 2" above the insulation materials and shall be secured in place to prevent displacement. Installation shields provided as part of a listed vent asystem shall be installed in accordance with the manufacture's installation instructions.

Christian Schneider · 02-13-2015, 10:10 PM

I'm not an inspector, but just finished installing one of these. I came here to see if there is any info about through-attic installations. That does look like an on-site fabricated insulation shield. The collar should stop insulation from getting between the chimney and outer barrel. Assuming double-wall Class A chimney pipe, clearance to combustibles is 2".

I'm surprised you all haven't seen these, but my city inspector hasn't seen one either, so I can't get my installation cleared until he finds out if this meets IRC 2009 specs - all through-attic installations he's seen have a chase built from framed support to roof sheathing. I researched much and these galvanized AISs are all I've seen, unless there's not enough space for the assembly (needs 12") between joists and sheathing. I saw elsewhere the barrel only needs to be 2" above the joists, but all I saw allow 10" of insulation above the joists. The one I installed seems to form a firestop (not sure if the sealed ceiling support forms a firestop).

This describes much about Class A chimney installations:
http://www.menards.com/main/store/20...nswarranty.pdf

Attached is a photo of Selkirk AIS installation, one of vent from wood stove, and specs dealing with AIS/UL103 (can't copy the text).

I saw on a post by Bob Harper ~"these chimneys need two points of support and the roof flashing doesn't count". I didn't see this in any installation manuals unless the chimney extends over 5 feet from roof - then it needs chimney support bars. Should I have another point of support?

attic insulation shield.JPG ceiling support.JPG AIS description.JPG