Are these jerk offs kidding me?
According to the NC code, I need venting in each roof rafter bay at the rate of 1 to 150 or 1 to 300 if I use a vapor barrier on the “warm side”. Think I’ll call the inspector on Monday to see which side is the warm side. Total idiots.
So I compute a joist bay at ~105 sq in. (2×8 framing). So each joist bay needs 105/150 = 0.7 sq in of ventilation? That is a 1/2″ hole.
Please tell me I’m not reading something correctly here. I don’t want to vent at all, but the guy is just staring at the book, saying he can’t allow it.
As another thought, my archy suggested a licensed mech engineer might be able to certify an unvented installation and provide a sealed letter to the building department. A lot like you would do with structural issues. Anybody ever heard of such a thing.
This is so idiotic.
MERC.
Replies
I wonder if you're getting the styrofoam chutes (wind tunnels is what they're called around here) you install against the bottom of the sheathing confused with the actual penetrations through the roof in interpreting the code. Just a thought.
I invented venting.
Edited 9/25/2004 5:54 am ET by greencu
>>Please tell me I'm not reading something correctly here.
You're reading it wrong.
The ratio is total _free_ vent space to total attioc floor square footage
1/2 at the eaves, 1/2 at the ridge.
Before you decide on what to do, talk to a roofer or home inspector as to what actually works in your area.
Sojourners: Christians for Justice and Peace
DJ:
Use ventilated soffit material and ridge vents. Every home here built within the last 15 years has soffit vents, although some hardheads are still using gable vents. If you already bought solid soffit material, use the metal strip vents. If you already installed the solid soffit material, cut holes in it and use the metal insert vents. The ventilation requirement is easy to meet. Don't use a vapor barrier in the ceiling - I have never seen it done here in central NC. If you think you need to reinvent the wheel - go ahead - it will go nicely with your horizontal stack vents ;-)
BTW - by "warm side" they mean the side toward the living space of the house.
>>BTW - by "warm side" they mean the side toward the living space of the house.
The way I learned it, the warm side is the, ah, warmer side.
In a totally heated space location, that would be inside; in a totally cooling space location, that would be the outside.
The concept is to stop the water vapor before it cools to the condensation/dew point.
Sojourners: Christians for Justice and Peace
Yes, in general terminology, you are correct. I was answering the question with respect to what building officials are looking for here in NC. IE - here in NC - if a vapor barrier is to be used it goes toward the living space. I live about 15 miles from DJ Merc. This is a mixed heating/cooling climate, but here vapor barrier is installed with respect to the heating season.
Edit to previous comment - paper vapor barrier is used with fiberglass batt insulation in ceilings - although that is more just to give a way to attach the batts, and is not a very effective vapor barrier at all. Matt