What are some of the ways that you provide ventilation for open rafters (craftsmen style?
Do you install factory made inserts or drill holes and back with mesh?
Do you vent every space or every other one?
Any ideas would be appreciated.
cje
Take what you want, leave the rest
Replies
Why do you want to vent the rafters? Is it new construction? If so, why not foam the roof deck instead of insulating the ceiling? You'll get better insulation, and better air sealing. If it's an old house, what problem are you hoping that venting will solve?
Andy Engel
Senior editor, Fine Woodworking magazine
An updated profile is a happy profile.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
It's new construction of my garage--isn't it satndard parctice to vent the rafters?
What am I missing?
cjeTake what you want, leave the rest
Venting will cool the attic space in the summer and prevent ice damming in the winter. The question is, are you heating/cooling the garage? If no, then why bother venting?
Venting will cool the attic space in the summer and prevent ice damming in the winter
<knights-who-say-NEE! voice>He Said it! He said the forbidden word!
IIRC, the textbook answer is that venting removes moisture which might otherwise condense on a cooler surface which would then be damaged by that moisture contact.
I can attest that venting my attic does nothing to make it cooler. There are those on this forum who can better attest to whether or not ice damming occurs with or without venting roof planes.Occupational hazard of my occupation not being around (sorry Bubba)
Venting is traditional, and until the recent recognition of hot roofs (unvented roofs), it was also code required. However, venting will do little to cool your attic in the summer, because the primary heat transfer mechanism in play is radiation, and venting doesn't have much effect on radiant heat transfer. It can help with ice damming, or it can create a minor vaccum that sucks heated air out of the space below, contributing to ice damming. Venting was originally proposed as a solution to wet attics. In fact, drying the spaces below has a greater effect on that problem than venting can.
So, I see little reason to vent other than mis-guided custom. But don't believe me. Go to http://www.buildingscience.com.
I think the insulation of the future is foam applied to the bottom of the roof deck.Andy Engel
Senior editor, Fine Woodworking magazine
An updated profile is a happy profile.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Well isn't that interesting--I'd never heard that--does anyone have any experiences with building non vented roofs in the south--I'm in Atlanta.
cjeTake what you want, leave the rest