Floor Joist 15 foot clearspan 24 on center?

[Uncle]

Here's the scoop.....We have an old old house. There are two rooms on the second floor that are sagging and one of the has a good amount of bounce. Right now we believe they have hand sawed oak joists that are 3 x 8. We are thinking of replacing them. What kind of material would you recommend replacing them with. Something very sturdy.

We would like to keep these dimensions for the beamed celing below.

15 foot span.

24 inchs center to center.

 

[bioman]

might check on micro lam products. sort of pricey, but worth the money !

 

[jimbom]

Live load of 30 psf and dead load of 10 psf. Mixed southern pine No. 1 Select Structural 2" x 10" (Fb of 1273 psi) would give you 15' spans at 24" on center.

 

[Reggie Dunlap]

I'd be looking at manufactured joists like the TJI's. They're stronger, straighter, and lighter than dimensional lumber. Any lumber yard should be able to do the calculations on what you need.