Nominal clay flue sizes

[willkil]

I'm pretty new to chimney rehabilitation, but a quick study. I've measured the two square flues on my chimney and would like confirmation of their nominal sizes. Here's what I measured and what I think their nominal sizes are:

Interior Size	Exterior Size	Proposed Nominal Size
6⅞"	8½"	8"
10⅞"	12½"	12"

Have I proposed the correct nominal sizes?

 

[bholler]

You are correct

 

[double-d]

Some manufactures of different components will call then 9 x 13 or 8 x 12. These components are usually adjustable with bolts or will fit different flue sizes. Such as Rain Caps or Dampers.

 

[willkil]

Some manufactures of different components will call then 9 x 13 or 8 x 12. These components are usually adjustable with bolts or will fit different flue sizes. Such as Rain Caps or Dampers.

Are you saying that (broken link removed to http://www.woodlanddirect.com/Seal-Tight-Chimney-Top-Damper) would fit my 12" flue? Makes sense as the specs on that page say this:

• Fits Flue Width/Diameter: 10"-13" | 15"-18" | 7"-10"
• Fits Flue Depth: 10"-13" | 15"-18" | 7"-10"

 

[bholler]

Are you saying that (broken link removed to http://www.woodlanddirect.com/Seal-Tight-Chimney-Top-Damper) would fit my 12" flue? Makes sense as the specs on that page say this:

Yes it will fit fine.

 

[willkil]

Thanks for your help @bholler and @double-d!