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


Stiffening Existing Floor Joists

Stiffening Existing Floor Joists

Stiffening Existing Floor Joists

I was recently asked to stiffen an existing floor system. They are planning on adding expensive tile, and are worried about cracking. The floor framing is 2x10 joists @ 16" o.c. with 1/2" and 3/4" sheathing spanning 15'3" and are way under for deflection. The product specs recommend l/720 to eliminate any cracking, which is difficult given the span and crowded nature of the basement (increasing depth would be difficult with wiring and duct work). Sistering on one or both sides does not meet the deflection criteria. Any recommendations on stiffening the floor, or avoiding tile cracking?

RE: Stiffening Existing Floor Joists

Add top and bottom steel plates? Or flitch plates? A little steel goes a long way.

RE: Stiffening Existing Floor Joists

Light gauge steel "C" joists.

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: Stiffening Existing Floor Joists

What about sistering with engineered lumber?

RE: Stiffening Existing Floor Joists

Adding a flush or drop beam to shorten the spans.

Mike McCann, PE, SE (WA)

RE: Stiffening Existing Floor Joists

most cost effective would probably add a LVL beam mid span (msquareds solution), and if that doesn't give the desired result laminate another D.Fir 2x10 to every joist in addition to the beam

RE: Stiffening Existing Floor Joists

Expanding: The tables I set up for 2x joists show 15'3 is max span of 2x10@16" with L/360 - cut the floor joists down the middle and add in a beam (make sure it isn't a continous span, you just want half length trib widths

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


White Paper - The Evolving Landscape of Commercial Battery-Powered Trucks
What’s driving the evolving landscape of truck electrification? What are the barriers, motivators and strategies for accelerating the electric transition? What insights and resources are available for today’s design engineers working to achieve industry disruption and evolution? For answers to these and other pertinent questions, read this white paper. Download Now
eBook - Rethink Your PLM
A lot has changed since the 90s. You don't surf the Web using dial-up anymore, so why are you still using a legacy PLM solution that's blocking your ability to innovate? To develop and launch products today, you need a flexible, cloud-based PLM, not a solution that's stuck in the past. 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