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


Snow Drift - spacing of mechanical units

Snow Drift - spacing of mechanical units

Snow Drift - spacing of mechanical units

ASCE 7 states that drifting does not need to be considered if the projection is less than 15 feet.   How close can these 15ft projections be to each other?   15 ft, 2 ft, 1/2 inch?  If the projection is 13'-4" would 5ft bee OK?

Also if you lift a projection off of the roof will drit loading be negated?    how high?   height of snow, heigth of drift, or even higher?    

RE: Snow Drift - spacing of mechanical units

Interesting thread. The Old BOCA Code I have uses the same 15 feet but the separation used in BOCA is in the direction of the drifting and NOT along the projection. Try contacting ASCE via email. Good Luck.

RE: Snow Drift - spacing of mechanical units

Depends on your judgement and how forgiving your roof system is.

Lifting the projection does little to limit drift.  I was just out to inspect a failed roof on a PEMB due to drift loads.  Come to find they added parapets around the perimeter of the roof.  Designer left a 12" tall continuous opening at the base of the parapets to "prevent drifting".  

Needless to say, it doesn't prevent drifting and it brought the building down.  I think any interruption in the wind deposits snow, so unless you're lifting it 6' high any lift isn't going to do squat.

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close