DIY Home Improvement Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
90 Posts
Discussion Starter #1
Okay, quick question, I installed R-19 fiberglass insulation in my vaulted ceiling, in 2 x 8 rafters. Someone, plumber on site, mentioned whether or not I was going to use the foam 'egg crate' things for ventilation.

It got me thinking but R-19 is less than 6" and the rafter is 7 1/2", I believe I should have plenty of an air gap between the ridge vent and the eves.

Please let me know your thoughts.
 

·
Registered User
Joined
·
11,730 Posts

·
Registered User
Joined
·
11,730 Posts
Cathedrals require baffles or you will wind-wash the fibrous insulation, negating its R-value 40-60%. http://www.reedconstructiondata.com/building-codes/pennsylvania/
As the outdoor air deposits its moisture on the insulation (great filter- think furnaces), expect 60-70% R-value loss; http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/bsi/90-controlling-heat.html

Expect to add 2x6 furring to the rafter bottoms before/after inspection to reach code minimum R-38, unless the inspector accepts R-30; http://publicecodes.cyberregs.com/icod/iecc/2009/icod_iecc_2009_4_par004.htm

for your State- under the IECC, 2009; http://www.reedconstructiondata.com/building-codes/pennsylvania/

This should all be listed on your approved plans for the permit...

Gary
 

·
Registered
Joined
·
90 Posts
Discussion Starter #9
Yes, my ceilings are vented via a ridge vent and eve vents.

GBR, I researched the links you referenced and even though they look 100% correct, the house was built with 2 x 8's and inspected as such. Why in the world and how could the BI require me to put in R-30 or higher which requires a higher rafter after it was all inspected and approved?

Doesn't make much sense to me.
 

·
Registered User
Joined
·
11,730 Posts
Me either. Your whole state is under that Energy Code, with no local amendments. My state requires R-49 (Zone 4 marine) as we have our very own Energy Code, so fortunate to go above and beyond the IRC, IBC, and IECC code minimum...surprised they didn't say anything before.

Gary
 

·
Registered
Joined
·
156 Posts
wen was your permit aproved?on your drawings did they call out the r values on the wall and roof sections? my permit was pulled last year prior to them updating the code so i fall under the older values. on my permit drwaings he highlighted te note on wall sections and wrote R13 and such. i had a long conversation with the building inspector on this as mine was stick framed with 2x12 rafters for a cathedral cieling- and how to insulate this properly and to achieve the r factor. under the current code this is impossible and now requires te rafter to be padded out or a scissor truss to be used to achieve this......

great links by the way....
 

·
Registered
Joined
·
90 Posts
Discussion Starter #12
wen was your permit aproved?on your drawings did they call out the r values on the wall and roof sections? my permit was pulled last year prior to them updating the code so i fall under the older values. on my permit drwaings he highlighted te note on wall sections and wrote R13 and such. i had a long conversation with the building inspector on this as mine was stick framed with 2x12 rafters for a cathedral cieling- and how to insulate this properly and to achieve the r factor. under the current code this is impossible and now requires te rafter to be padded out or a scissor truss to be used to achieve this......

great links by the way....
Last year, around July-ish. Per my township the homeowner is allowed to produce their own drawings. I was checking them out the other day and there's nothing on there stating anything about insulation, etc. The only thing called out is with regards to needing permits for anything else, i.e. electrical, plumbing, mechanical, etc.
 

·
Registered User
Joined
·
11,730 Posts
I'd give the field inspector a call and ask him. Let us know the outcome...

Gary
 
1 - 13 of 13 Posts
Top