Contact US

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!

*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

Equivalent Fluid Pressure for Snow

Equivalent Fluid Pressure for Snow

Equivalent Fluid Pressure for Snow

I have a tall metal stud roof parapet that was designed to resist the applicable components and cladding wind forces.  Behind this parapet is the potential for up to 7 feet of snow drifting.  The roof system has been designed to accomodate this drifting load.

Now, a peer reviewer brought up the subject of wether or not the parapet had been designed for horizontal thrust or bending due to snow "pileup".  The analogy I come up with is equivalent to soil pressure on a basement or retaining wall.  If soil density is approx 110 pcf and EFP roughly 35 psf, then if snow denisty is 18 pcf, would EFP snow equal 6 psf?

Any thoughts, comments, ideas?  Overall, I think the wind pressure will govern the parapet stud design, but I now need to justify that.

RE: Equivalent Fluid Pressure for Snow

I don't think the snow would ever control over the wind for perimeter parapets.  In addition, the UBC and ASCE 7 have NO provision for lateral loads from snow - all is vertical gravity.

RE: Equivalent Fluid Pressure for Snow


I agree with JAE.   The lateral load of snow should be  minimal, and the wind load will control.    

If you want to compare the lateral pressure of snow with those of the soil, snow has a larger angle of internal friction, a larger cohesion, and a smaller unit weight.   These properties will reduce the lateral pressure considerably.

RE: Equivalent Fluid Pressure for Snow

One special case I am thinking. If the roof system is sloping towards the wall, ice may form a solid wedge and exert pressure on wall by sliding towards it depending upon the slope of the roof.

RE: Equivalent Fluid Pressure for Snow

Another thought for buildings with parapets, what happens if a roof drain becomes clogged?  You should always provide an "overflow scupper" just in case the roof drain is clogged by leaves or ice.  Water on the roof gets pretty heavy pretty fast!

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! Already a Member? Login


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