×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Effect of ridge vent (unnailed plywood edge) on structure

Effect of ridge vent (unnailed plywood edge) on structure

Effect of ridge vent (unnailed plywood edge) on structure

(OP)
I have been told by the inspectors that roof plywood needs to be nailed at the ridge and at the eave blocks to provide a proper "diaphragm". Yet To provide continous ventilation in the rafter bay between the eaves and the opening at the continous ridge vent  I cannot install blocking or a ridge  board for nailing without restricting the air flow between the eaves (exterior wall) and the ridge vent. Assuming installed insulation that provides an inch of space at the top of the rafter bay for the ventilation.

This  is specifically in  regards to a standard framed residential roof with rafters set on top of a ridge beam that spans 18' and 14' for a total length of 32'. I have sometimes seen simpson straps  installed over the ridge from rafter to rafter....does this tie the diaphragms together? Any suggestions or explantion of  this would be great.

RE: Effect of ridge vent (unnailed plywood edge) on structure

smartbuilder they usually use strap only when you use ridge beam with I-joists rafter.  Usually people tend to use flush ridge instead and use lssu hanger.  If you drop the ridge then you have to use blocking between I-joist and then strap the joists together.  The reason you need to strap them together is because you cant really toe nail an I joist onto the ridge board.  I never specify dropped ridge beams w/ I-joists for that reason.

As far as ventilation, I do not know.  I always leave it to the architecht.  

RE: Effect of ridge vent (unnailed plywood edge) on structure

I found a reference to this in the APA literature called "Introduction to Lateral Design" which states that "A continuous ridge vent can be used with an "Unblocked Diaphragm". An unblocked diaphragm has no requirement for blocking between unsupported edges of adjacent panels. It also states you could stagger the blocking in a "blocked diaphragm" allowing vents every other truss bay. You then provide double the nailing requirement at the blocked bays. So you have two choices: design the diaphragm as unblocked or stagger your vents. I don't know your ventilation requirement, so that could dictate which one you use.
APA produces tons of literature to guide you.

https://www.apawood.org/

Good luck...

RE: Effect of ridge vent (unnailed plywood edge) on structure


I'VE USED DETAILS WHERE YOU DRILL HOLES IN THE BLOCKING TO ALLOW FOR AIR MOVEMENT. SIZE AND NUMBER OF THE HOLES DEPENDS ON THE DEPTH OF THE BLOCKING AND THE SHEAR FORCES YOU ARE TRYING TO TRANSFER. DON'T KNOW HOW THAT INTERFACES WITH YOUR INSULATION LAYOUT THOUGH.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources