×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Gypsum Board/Drywall, Brittle Finish?

Gypsum Board/Drywall, Brittle Finish?

Gypsum Board/Drywall, Brittle Finish?

(OP)
Table 1604.3 in the IBC has a deflection limit for "brittle" finishes of L/240, and L/120 for "flexible" finishes.  (This is with regard to an interior partition wall).  "Brittle" and "flexible" don't seem to be defined anywhere.  Is there somewhere I'm not looking that defines these terms?

I've always considered gypsum board and drywall a brittle finish for deflection purposes.  Am I being too conservative?   

RE: Gypsum Board/Drywall, Brittle Finish?

If it cracks or breaks at a l/121 or less than it is brittle? I do not considered wallboard to be brittle.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Gypsum Board/Drywall, Brittle Finish?

I always thought L/360 was the limit for rigid finishes (it is in our code) and I have always included drywall in the rigid class.  Drywall will certainly bend more than L/360 with no problems, but the taped joints will crack if you look at them wrong which is the same as the drywall cracking as far as the building owners/occupants are concerned.

RE: Gypsum Board/Drywall, Brittle Finish?

Drywall is a flexible finish. A brittle finish would plaster on lath.

RE: Gypsum Board/Drywall, Brittle Finish?

(OP)
Thanks for the replies.  So 2/3 for flexible?  Is there any literature to support that it performs well at l/120?  Gypsum association or something?  

RE: Gypsum Board/Drywall, Brittle Finish?

@LowLax: I Googled and found the following info on Structural Building Components Association web site www.sbcindustry.com.
For drywall assemblies it is desirable to limit deflection to L/240 and to never exceed L/120.

RE: Gypsum Board/Drywall, Brittle Finish?

shobroco... l/360 is the typical limit for rigid ceilings such as plaster. Drywall is usually not limited to that criterion as noted in the OBC

RE: Gypsum Board/Drywall, Brittle Finish?

The attached link will get you to some span tables for Gypsum board walls with L/120, L/240 and L/360 allowable deflections.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Gypsum Board/Drywall, Brittle Finish?

Chapter 2 in USG's Gypsum Construction Handbook states: "For drywall assemblies it is desirable to limit deflection to L/240(L = length of the span in inches) and to never exceed L/120 (L/180 in some codes). The preferred limit for veneer assemblies is L/360 and should not exceed L/240."

http://www.usg.com/resource-center/gypsum-construction-handbook.html
 

RE: Gypsum Board/Drywall, Brittle Finish?

I usually hold to L/240 for total loads and L/360 for live loads such as wind or seismic, sometimes even higher if it is a high end structure.  The same standards I would also apply to the ceiling structure.  I would also consider an exterior stucco finish to be brittle.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
 

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


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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