Drywall clearance to DuraVent pipe

[Goffredo]

Hey gang,

I had a Hearthstone Modena gas stove professionally installed with vertical direct vent straight through the roof. I need to patch up the hole in the ceiling that was left over from the old fireplace (pictures below). I'm not sure how much clearance to allow between the hole I'm cutting in the drywall patch that will go around the chimney pipe, and the actual chimney pipe itself. Also not sure if I should be using something other than drywall for this application.

The chimney pipe running vertically up out of the gas stove is two sections of DuraVent Direct Vent Pro DVA46-16AB. The installer left a DuraVent 46DVA-DC Ceiling Support / Wall Thimble Cover on the pipe, which I plan to attach to the drywall patch once it's installed.

The clearance information between the drywall and the pipe does not appear in any of the following:

• The Hearthstone Modena installation manual
• The DuraVent Pro installation manual

While the latter does provide a table of framing / cutout dimensions, it does not have an entry for the 46DVA-DC.

Please, can someone give me some help here? My gut feeling is to cut the drywall opening a tad smaller than the wall thimble cover (which is a 13x13 inch square) and call it a day. Here are some pics if it helps!

 

[DAKSY]

Vertically, the clearance to combustibles is one inch on all sides.
Horizontally, it's one inch on both sides & the bottom. Two inches on top.

 

[Goffredo]

Vertically, the clearance to combustibles is one inch on all sides.
Horizontally, it's one inch on both sides & the bottom. Two inches on top.

Yay! Thanks for your help, now I can finish this project!!