AVS Forum banner

Status
Not open for further replies.
1 - 4 of 4 Posts

·
Registered
Joined
·
1,014 Posts
Discussion Starter · #1 ·
My existing floor joists are 9 1/2" TJI I-joists 16 o.c. 14'-6" span. I will be inserting ceiling joists inbetween, with a 3/4" drop. If I use 2x8 dimensional lumber, how would I do the cross-bracing? One end of the joist I have open access to. The other end has 8" supply runs in over 1/4 of the joist cavities, the main HVAC supply lenticular hanging underneath, and two 3" PVC pipes hanging underneath, so any real attempts at bracing are out of the question.


What is the reason some people use LVL over dimensional?


What if I used another set of I-joists, instead? ($16 each vs $9.50 for 2x8, so would only be another $110 or so for 23' room)


I will be hanging double-sheet drywall, 3/4" MDF soffits and a 165# Barco CRT with hush box, so this will also add to the dead load.


Thanks for any help. I have workers lined up for this weekend, but now am nervous about my construction plans.


Geordon
 

·
Premium Member
Joined
·
8,712 Posts
Cross bracing is only to prevent the dimensional lumber from warping. LVL and the "I" joists won't warp. If you get a good, high quality, dried, dimensional 2x8 it's not likely warp either unless you have wild humidity swings in your home.
 

·
Registered
Joined
·
1,014 Posts
Discussion Starter · #3 ·
Thanks, Dennis. I thought I read in one of the other threads that cross-bracing was to prevent twisting of the joist due to downforces. I didn't quite understand the reasoning. Maybe the poster really meant warping, but just called it twisting.


Geordon
 

·
Registered
Joined
·
7,780 Posts
Some folks (like me) have used LVL even though it's quite costly. The reason is that it's perfectly stable regardless of humidity or stress. 2x8 lumber will move. Some a little, some a lot.


Most use dimensional. The problem is that you'll never know if its twisted after you drywall.


Ted
 
1 - 4 of 4 Posts
Status
Not open for further replies.
Top