Firewall 706.5 ZipR Sheathing

[northside1]

I have a building that is divided with firewalls to utilize Type VA construction and is also required to meet Energy Star MFNC. I have worked on several similar buildings without continuous insulation requirements and understand the sheathing options to meet the firewall termination requirements in those instances. What sheathing material have you guys been seeing adjacent firewalls with ZipR sheathing?

I am concerned about the overall thickness of the assembly and location of the foam if I switch to a separated product in the 4' either side of the wall. To avoid the issue, I am considering removing the continuous insulation idea and going back to "advanced framing" to meet the EStar requirement since the building is only 4 stories.

I just signed up to the forum but have read your thoughts for many years. Thanks in advance!

 

[northside1]

Needed to add the following..... There are window stacks within 4' of the firewall that I would like to avoid protecting. This section of the building will have an NFPA 13R system and is R2.

 

[Jay Smith]

How thick is your insulated sheathing?

 

[northside1]

It is the R-3 product so it is a total 1" thickness including the wood.

 

[Jay Smith]

It seems like in the fire wall zone you could replace that with gypsum sheathing covered with Zip sheathing.

 

[northside1]

I thought about that but then there wouldn't be continuous insulation in those sections of the building. If I did foam on top of the gypsum sheathing there are potentially thermal issues (as well as detailing) from the position of the foam changing from inside to outside in that section also.