Zero Clearance vs Insert for Fireplace with Wall Extension???

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New Member
Dec 4, 2020
Hi all,

I'm in the process of remodeling my basement, and I have a question I cannot seem to answer by researching online:

I have extended my fireplace surround from the original masonry chimney stack by approximately 16" (metal framed wall with cultured stone veneer). I intend to install a gas fireplace in the opening where the original wood burning fireplace was located. I had intended to install a Heat&Glo SUPREME-I35-IFT insert into this space, but I just noticed that it says I can only extend the wall 12".

Alternatively, I looked at installing a zero-clearance unit (Heat & Glo SL-7). However, I understand that these need to be installed prior to cement board/masonry veneer. Is this understanding correct? I'm supposed to have the masonry installed this weekend, and I think my wife will kill me in my sleep if we don't get this done.

Is there a safety concern with using an insert in this situation? Is it possible to install the SL-7 after the masonry is installed?

Any help would be greatly appreciated.