Gas fireplace vent under deck

SO another question regarding a recent inspection. Gas fireplace vent was noted under a deck about 16" down from bottom of deck. Obviously not a great idea but I can’t find any particular documentation regarding proper horizontal install recommendations. One manufacturer even shows it being allowed and only 12" clearance under balcony or deck in their installation manual. Any ideas?



The answer is what ever the installation documents give for clearances.

Thanks for the reply. I couldn’t determine the manufacturer…