Firebox remodel Q for framing/veneer stone to install gas insert

[Majestic33LVDR]

Note: 2 pics provided below -
Helping a relative remodel a 1973 fireplace (unused >10yrs) for pro installation of Napoleon Oakville GDIX3N gas insert.
Firebox in good shape after demo -only requires replacing some mortar at outside perimeter of fire bricks .
First row of firebrick at base of firebox removed (unstable) along with the brick wall facing to get everything at drywall depth.
Plan to fabricate a stud/HardieBacker wall to install stacked veneer stone from floor to ceiling (no hearth).
Original firebox depth will be restored by the veneer stone wall.
The Oakville install manual requires to be recessed into a "non-combustible appliance".
(Have a zero cleareance Majestic 33LVDR screwed directly into wood stud framing at the front, so no understanding of different req's!)
Any recommendations for non-combustible construction of the stud wall around the firebox perimeter?
ie: Build the framing with wood at dimensions that allow reinstalling the first row of firebrick on it, and removed brick up the sides?
That leaves the top outside edge of the firebox -lay the removed lintel back across the two columns of reinstalled brick?
Then lay wood framing on the lintel to continue the wall to the ceiling?
Or consider metal studs? Could 1/2" HardieBacker be cut to cover entire floor of firebox and installed along the extended sides/top ?
Is refractory mortar req'd to install any firebrick/brick at firebox outer perimeter?
Want to do it right, but not waste time over-engineering. Unsure how far to go with the "non-combustible" req.
Any feedback/ideas appreciated -and thanks for your time!

From Installation Manual:
Pg 10 Appliance must be recessed into a vented non-combustible wood-burning appliance (prefab or masonry) only.
Pg 11 Make sure that ... wood-burning appliance in clean and sound condition and constructed of non-combustible materials.

 

[Lennox65]

The HeatnGlo inserts have a section of the install manual that covers this. I have attached the pages for reference.

 

[Majestic33LVDR]

The HeatnGlo inserts have a section of the install manual that covers this. I have attached the pages for reference.

Lennox65, thanks for your reply-
That HeatnGlo install manual has much better detail than provided in Napoleon's manual:

https://www.napoleon.com/sites/default/files/fireplaces_products/Oakville%E2%84%A2-3-_-3E-_-G3-_-X3-Installation-Manual.pdf

That manual is probably a close approximation of what should be required -a comparison:
Heat&Glo Escape-30-IFT min opening: 30-1/2" W X 22-5/8" H X 16-5/8" D -rated 36,000 BTU
Napoleon Oakville GDIX3N min opening: 29” W X 21-1/2” H X (14-3/8+4 for fan)=18-3/8” D -rated 30,000 BTU

Initially surprised at the 56" Y value being 33" higher than the 22-5/8" H unit, but make sense when consider heat rises.
Going to bring this to the Napoleon dealer/installer to request specific requirements for the Oakville unit.

Thanks again
Anyone else with experience/perspective to add appreciated!

 

[bholler]

Lennox65, thanks for your reply-
That HeatnGlo install manual has much better detail than provided in Napoleon's manual:

https://www.napoleon.com/sites/default/files/fireplaces_products/Oakville%E2%84%A2-3-_-3E-_-G3-_-X3-Installation-Manual.pdf

That manual is probably a close approximation of what should be required -a comparison:
Heat&Glo Escape-30-IFT min opening: 30-1/2" W X 22-5/8" H X 16-5/8" D -rated 36,000 BTU
Napoleon Oakville GDIX3N min opening: 29” W X 21-1/2” H X (14-3/8+4 for fan)=18-3/8” D -rated 30,000 BTU

Initially surprised at the 56" Y value being 33" higher than the 22-5/8" H unit, but make sense when consider heat rises.
Going to bring this to the Napoleon dealer/installer to request specific requirements for the Oakville unit.

Thanks again
Anyone else with experience/perspective to add appreciated!

The heatnglo instructions don't apply to your insert. Your insert requires it be installed into code compliant wood burning fireplace. That means your new face needs to be built up to current code for a wood burning fireplace.

 

[Majestic33LVDR]

Met with the mgr at dealer/installer today, who has installed many inserts.
He said metal framing/concrete board to re-frame/extend the firebox outside perimeter approx 5" is acceptable.
Also said, if desired, that concrete board could be cut to cover entire floor of firebox over the current firebrick.
Insert sits directly on firebox floor, and will have an approx 6" space between sides/top to the framing/concrete board.
That space will be hidden by the 4-sided backer plate.
Plan to use metal studs/concrete board for entire wall being built to support veneer stone.

He also said many times they have arrived to perform the insert install and found similar renovations that needed rework.
Being risk-averse and meeting with the installer to confirm design acceptable before renovation has benefits!

 

[bholler]

Met with the mgr at dealer/installer today, who has installed many inserts.
He said metal framing/concrete board to re-frame/extend the firebox outside perimeter approx 5" is acceptable.
Also said, if desired, that concrete board could be cut to cover entire floor of firebox over the current firebrick.
Insert sits directly on firebox floor, and will have an approx 6" space between sides/top to the framing/concrete board.
That space will be hidden by the 4-sided backer plate.
Plan to use metal studs/concrete board for entire wall being built to support veneer stone.

He also said many times they have arrived to perform the insert install and found similar renovations that needed rework.
Being risk-averse and meeting with the installer to confirm design acceptable before renovation has benefits!

The problem is what they told you does not meet the requirements for your insert.

 

[Majestic33LVDR]

bholler, thanks for your feedback. I'm here to learn -
Can you provide any clarification/detail for "code compliant"?
I respect your almost 28K posts, and also respect that the installer has many years of experience, installed hundreds of inserts and is very knowledgeable.
Therefore, my dilemma is receiving different recommendations from two experts.

Installation Manual pg 11 says "a wood-burning appliance constructed of non-combustible materials" That's it -quite vague.
Apparently the conflict is regarding the definition of non-combustible materials?

Thanks again for your time

 

[bholler]

bholler, thanks for your feedback. I'm here to learn -
Can you provide any clarification/detail for "code compliant"?
I respect your almost 28K posts, and also respect that the installer has many years of experience, installed hundreds of inserts and is very knowledgeable.
Therefore, my dilemma is receiving different recommendations from two experts.

Installation Manual pg 11 says "a wood-burning appliance constructed of non-combustible materials" That's it -quite vague.
Apparently the conflict is regarding the definition of non-combustible materials?

Thanks again for your time

I also have many years of experience and have installed hundreds of inserts as well.

When the manual states the insert must be installed into a woodburning fireplace that (according to all code officials and manufacturers I have talked to) implies that the fireplace meets minimum code requirements.

Look up IRC chapter 10. That will give you all of the applicable requirements

 

[Majestic33LVDR]

Thanks
Appreciate the info and I will do that.

 

[Majestic33LVDR]

Some Q's after reviewing IRC Chapter 10 and thinking more on this.
That strict code is for a firebox interior exposed to a roaring fire/hot embers/cinders/smoke, and assume higher BTU than the 30,000BTU Napoleon GDIX3 insert generates. Can understand the code makes sense for wood fire applications.
For the insert, Romex wire is routed into the firebox and batteries and related electronics are located inside the walls of the insert.
I wouldn't put Romex/batteries/electronics into a roaring fireplace, but they go in the firebox to support the insert.
There will be 3-4" space between the sides/top of insert and the metal stud/concrete board framing.
There are many references online (including here) about using metal studs/cement board around firebox gas inserts.

Based on the above, a bit confused b/c the IRC Chapter 10 seems like overkill for this application.
Acknowledge that you're an expert, but the other expert/installer approved the plan.
Maybe there's a local code for this application that the installer is familiar with?

Thanks again for your time

 

[bholler]

Some Q's after reviewing IRC Chapter 10 and thinking more on this.
That strict code is for a firebox interior exposed to a roaring fire/hot embers/cinders/smoke, and assume higher BTU than the 30,000BTU Napoleon GDIX3 insert generates. Can understand the code makes sense for wood fire applications.
For the insert, Romex wire is routed into the firebox and batteries and related electronics are located inside the walls of the insert.
I wouldn't put Romex/batteries/electronics into a roaring fireplace, but they go in the firebox to support the insert.
There will be 3-4" space between the sides/top of insert and the metal stud/concrete board framing.
There are many references online (including here) about using metal studs/cement board around firebox gas inserts.

Based on the above, a bit confused b/c the IRC Chapter 10 seems like overkill for this application.
Acknowledge that you're an expert, but the other expert/installer approved the plan.
Maybe there's a local code for this application that the installer is familiar with?

Thanks again for your time

IRC is the code that applies to you. I agree it probably is overkill but that is what is required. The manufacturer could specify otherwise if they tested something else and determined it was safe. But they didn't so you are required to adhere to that code.