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what size floor joists needed?


redss55's Avatar
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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.

 
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chandler's Avatar
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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.

 
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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.

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

Maximum Span Calculator for Joists & Rafters

 
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