We are about to start a new construction with a SIP roof and cold roof over that (SSM).

When is the appropriate time for the DWV work - after the SIPs are installed but before the cold roof is built up, or after the cold roof is complete?

Do both penetrations (SIP and cold roof) have to be flashed? Seems like an obvious yes, but I have to ask.

Thanks in advance for any advice or amplifying information.

I am not sure what SIP roof is... But as a general rule, yes, install flashing on both roofs. The lower roof may condensate so roof flashing is needed.

Plumbing vents are usually ran through rough framing ( and ply on the roof ) and before the actual roof covering is installed. Roofer sets flashings as he installs roof covering material around vents

Hope that helps

Milo

SIP are structural insulated panels and they have very specific requirements for roof penetrations... must be insulated very carefully!

Since this job is not a DIY PROJECT, I would strongly suggest contacting the SIP supply company... if you follow their specific requirements you can not go wrong with warranty issues down the road!

Mark