Insulation and OWB ownership.

[Fred61]

Sometimes we give up energy efficiency in favor of style. In your case it's scissor trusses and perhaps airflow through the attic that will vent heat generated by the sun on the roofing material as well as moisture generated within the home and roof ice. Trusses could be built with vaulted parallel chords or double inverted vault as well as several vault designs that may be more attractive in design than a simple scissor truss. Google truss design or maybe just trusses. I personally wouldn't build a roof that didn't have a good positive air flow in the attic but I've only built here in New England and don't really know what is required in warmer and/or drier sections of the country. I do know what we need for a warm and healthy home interior.

 

[Flying Dutchman]

http://new.dutchcrafttruss.com/wp-content/uploads/2011/11/Scissor-Truss.gif

That is what I have basically. So... you are saying it sucks? Rookie mistake?

They are installed on part... but I have an opportunity to not install them on the rest of the house...

 

[BoilerMan]

I have scissior trusses with a 16" heel 2/12 ceiling and 5/12 roof line. If you want a true vaulted ceiling with ceiling and roof same pitch, I'd consider at least 4" of foil faced foam on the bottom of the truss leaving the airspace for ventelation. Depends on the span your talking about.

TS

 

[711mhw]

+1 on the http://www.greenbuildingtalk.com/Forums.aspx. ask some of your questions there. A cheaper alternative to spray foam is cut & fit ridgid foam with special attention to filling all gaps with "can" foam. I believe that multiple layers are ok providing (see filling gaps) above. A tight house is what you want, but humidity & fresh air must not be neglected.