[Greenbuilding] Insulating a cathedral roof

[Lynelle Hamilton]

Hi Listers,

My new build has a shed roof with a 4:12 pitch; low side on the north. 
It is a trussed roof. Trusses are in 2 parts (lengthwise) with an 
approximately an 18" depth. House has a partial second storey, extending 
over the entire south facade and part of the north facade.

Interior, there is a cathedral ceiling over approx 60% of the north side 
of the house and 100% of the south side (second story). The remaining 
40% of the north side is used for storage and would have the potential 
for a wider range of insulation options.

Roof is standing seam steel over ply with ice and water dam over the 
entire surface. Two stack vents penetrating (one 6' from the high side 
and another 16 feet from the high side. One chimney penetration either 
16 feet from high side OR 4 feet from low side.

Trusses sit on top of 14" Durisol.

I've read a ton and talked with local builders (many of whom think R-65 
is overkill and I am crazy). There is no consistency in approach. I am 
no further ahead.

Thus, I have a few questions:

 1. Vented or unvented roof?
 2. Either way, I'd like to sock at least R-65 into the cavity. What's
    the best way to do this?
 3. Should I isolate the truss from the wall top and if so, how? Rigid
    Roxul? Gasket?

Many thanks for any expertise the group offers.





---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20171227/c7e87bc6/attachment.html>