Floor Joist Size?


Old 09-22-04, 06:10 PM
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Floor Joist Size?

My wife and I are wanting to build this little house. Just wanting advice on what size floor joist I should use for the first floor and the second floor. All spans will only be 12 ft. Should I go with 2 X 8's or 2 X 10's? Thanks!

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Old 09-23-04, 12:12 AM
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2x8 at 16"oc.
Old 09-24-04, 04:55 AM
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It depends upon the species and grade of the lumber.

#2 Southern Spruce-pine-fir won't span 12 feet nor will some other common framing grades at 16" on center.

Better to choose 2x10s at 16" on center even if it is overkill.

You will avoid springy floors and increase the load capacity of the floor.

Another consideration is how and if this floor will need to be insulated for your climate.

2x10s make the most sense all about.

Span calculator:


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