Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

what size floor joists needed?

redss55's Avatar

Join Date: Jun 2009
Posts: 12

07-09-09, 12:32 PM   #1  
what size floor joists needed?

I am planning to add a room at the 2nd level above my living room which is currently 2 stories tall.

The joists will span 15 feet. What type of joists are recommended so that the floor won't be bouncy? Different people tell me different things...2x10s, TGIs, LVLs, etc... and I need to decide the best for the money.

Sponsored Links
chandler's Avatar
Banned. Rule And/Or Policy Violation

Join Date: Dec 2005
Posts: 39,968

07-10-09, 03:41 AM   #2  
I would recommend either LVL or engineered I-beams, but in all fairness, you should consult an engineer to see the entire load picture. All we see is a simple building, but I am sure it is more complicated than that, and any advice we give here could jeopardize safety and integrity.

ecman51's Avatar
Banned. Rule And/Or Policy Violation

Join Date: May 2007
Posts: 8,629

07-10-09, 07:34 AM   #3  
2 x 4's will really bounce/break. 2 x 6's will really bounce/break?, or stay bowed after a while. 2 x 8's will bounce - better though if bridged. 2 x 10's will bounce with herd of elephants. 2 x 12's may support elephants without bouncing much. The laminated stuff today is lighter yet stronger in these regards.

I simply posted this half-wimsical reply because of the query about bouncing which is sort of subjectory. I'd imagine there should be architectural span and load sites available for review somewhere, you would think.

HeresJohnny's Avatar

Join Date: Jan 2006
Posts: 3,484

07-10-09, 09:16 AM   #4  
I use this site from time to time.

Maximum Span Calculator for Joists & Rafters

Search this Thread