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llmonty · 2nd March 2010

You are so right regarding code. I am in Richmond, VA so we are in the same climate. The architect's plans called for R-30, more than enough for our weather. R-38 makes it just about impossible to build a roof using code-accepted materials like 2x8s or 10s.

We are using 2x10 top chords/rafters for the trusses. Besides the r-value code requirements there seemed to be a moisture barrier and air leakage benefit to this suggested as part of an unvented roof redesign. The unvented design was a change midway through the build because of some other issues, and became a bit of a frustrating experience to research. Just want to make sure we don't create a moisture/mold problem.

2nd March 2010	#632
llmonty Gear nut Joined: Feb 2009 Posts: 97	You are so right regarding code. I am in Richmond, VA so we are in the same climate. The architect's plans called for R-30, more than enough for our weather. R-38 makes it just about impossible to build a roof using code-accepted materials like 2x8s or 10s. We are using 2x10 top chords/rafters for the trusses. Besides the r-value code requirements there seemed to be a moisture barrier and air leakage benefit to this suggested as part of an unvented roof redesign. The unvented design was a change midway through the build because of some other issues, and became a bit of a frustrating experience to research. Just want to make sure we don't create a moisture/mold problem.