Ceiling support box options - what's best to use?

[boomvan]

Hi guys, I did a quick search and came up empty on this question. I'm a little new to this stuff.
I'm doing a new chimney install using 6" Duravent Duratech chimney, going through a simple flat ceiling and through a 6/12 pitch roof. Has R60 fiberglass insulation in ceiling. I haven't cut the hole yet and measured the depth of insulation...
What's the benefit of using a single 24" tall square ceiling support box vs a 2 piece combination of 6" attic insulation shield on top of a 6" flat ceiling support box?
Direct examples are the:
Duravent 6DT-CS24 24" tall ceiling support box (broken link removed to https://www.northlineexpress.com/6-duratech-24-square-ceiling-support-box-9438b-9438b6dt-cs24-7052.html)
vs
Duravent 6DT-FCS 6" support box (broken link removed to https://www.northlineexpress.com/6-duratech-flat-ceiling-support-box-6dt-fcs-7061.html) and Duravent 6DT-IS attic insulation shield shield link

Or do I need to be using both, the tall 24" support box in addition to the attic insulation shield?

Thanks
Tim

 

[bholler]

Hi guys, I did a quick search and came up empty on this question. I'm a little new to this stuff.
I'm doing a new chimney install using 6" Duravent Duratech chimney, going through a simple flat ceiling and through a 6/12 pitch roof. Has R60 fiberglass insulation in ceiling. I haven't cut the hole yet and measured the depth of insulation...
What's the benefit of using a single 24" tall square ceiling support box vs a 2 piece combination of 6" attic insulation shield on top of a 6" flat ceiling support box?
Direct examples are the:
Duravent 6DT-CS24 24" tall ceiling support box (broken link removed to https://www.northlineexpress.com/6-duratech-24-square-ceiling-support-box-9438b-9438b6dt-cs24-7052.html)
vs
Duravent 6DT-FCS 6" support box (broken link removed to https://www.northlineexpress.com/6-duratech-flat-ceiling-support-box-6dt-fcs-7061.html) and Duravent 6DT-IS attic insulation shield shield link

Or do I need to be using both, the tall 24" support box in addition to the attic insulation shield?

Thanks
Tim

You should have an insulation shield regardless unless the tall box will go all the way up to the roof and be covered by flashing

 

[stoveliker]

For r60 the 6" is too short?
The shield needs to be tall enough to prevent any insulation from touching the pipe.