Replacing Actual Lumber Floor Joist with Nominal Lumber
Harrison01
| Posted in Construction Techniques on
I had to gut my bedroom down to the sill plates because of rot and termite damage. I have replaced the sill plates now, but now I am stuck with a problem. The old floor joist were actual lumber 2x8x14 and notched so the old wood floor was 7″ from the sill plate. The room is 14′ x 14′. 2x8x14 SYP #2 won’t span that far and 2×10×14 would make floor in bedroom about 2″ higher than the living room. Is there a way to put a support beam in the middle to shore up the live load or should I bite the bullet and use the 2×10×14 SYP? That would create an issue down the line. I thought about trying an I-joist but it was about 70 dollars per joist and I need 10.
Replies
Why not use the 2x8x14 w. 12” centers or double up the 2x8 w. 16” center. Just make sure you glue and screw properly
I had thought about that but I have looked up several different charts for load bearing loads and they differed enough that I was worried that wouldn't work.
Yep. Go to 12 in. centers. Here's a span chart FYI: http://www.southernpine.com/app/uploads/SPtable1_060113.pdf
Thank you, I had thought about it but the charts I found had different numbers. I was going to use #2 boards, but I might as well buy the #1 boards as well since they aren't to expensive. Give myself a little more piece of mind.
Typically for sawn lumber notches at the ends of the member shall not exceed one-fourth the depth of the member. The 2x10 can be notched at the end to lower it the 2” needed to match floor height. Check with local codes and jurisdiction to verify.
Thank you, I will check and most likely go this route. I want it done right and not have a bounce.
mdiehl has got it right. Bending is not at factor at the bearing ends. Normally, only shear needs to be considered and rarely is it a factor in simple floor framing.
You need to be careful in substituting 2"x8"s @ 12" o.c. Reducing the depth of the joist could increase the bouncing factor even though they would meet the span requirements.
Go to you lumber supplier. Often they have engineering services at no cost.
You answered the worry i had about using 2×8 lumber.
@oops, mdiehl. the original joist were 2x8 notched to 7” to fit. absolutely nobody would approve a 2x10 notched to 7” at 16” centers
Go with the 2x8 notch the 1/2” out and go to 12” oc. It will be stronger than previous joist
The end of a joist may be notched up to 1/4 of its depth. A 2x10, actual depth of 9 1/4 may be notched up to 2 5/16” at the bearing ends. This is standard code approved practice, R502.8 of the IRC. 2x8 12”oc may work but 2x10 notched at bearing ends will too. There are options. Hope this helps Harrison01.
you could also put blocking between the joists to transfer some to the load to adjacent joists and add a 2x4 at the bottom to create an Ibeam of sorts that should be stiff enough
guessing you have access in the basement to do this
12 " O.C. still sounds like the best way to go
good luck