Comments on: Selecting TJI Floor Joist Sizes

By: Todd

Todd — Wed, 23 Nov 2011 23:44:43 +0000

Typically the best solution is one that uses 16″ o.c. spacing. That spacing works well with 3/4″ sub-floors and finished flooring and it requires less labor than a 12″ o.c. spacing. Obviously there are times when that won’t work but that’s typically my preference.

By: Larry

Larry — Wed, 23 Nov 2011 21:17:06 +0000

Hi Todd,
First off, thanks for putting this website together! Very helpful.
I am a home designer and have a question about TJI sizes/ spacing vs. cost. In your experience, is it less expensive to go with a tighter spacing with a lighter joist, or wider spacing with a heavier joist?
Regards, Larry

By: Todd

Todd — Tue, 04 Oct 2011 16:53:25 +0000

I would do every joist so the floor has an even distribution of stiffness. Not sure what you mean by staggering, I’d just use an 8′ long piece at mid-span, both sides of the web.

3′ is more than enough, 4′ spacing willl likely work well as well.

By: Fernando

Fernando — Tue, 04 Oct 2011 16:37:52 +0000

When adding the plywood, to both sides of every other joist, should I just glue and screw both pieces to the middle of the joist, or should I stagger the pieces, on each side of the joist? Should I still add the plywood to every other joist? Do you think 3′ is a good space, for the bridging, or should it be more or less?

By: Todd

Todd — Mon, 26 Sep 2011 17:52:09 +0000

From your description it should like you’re trying to fix “bouncing” of the floor. This is due to what we refer to as live load. So no jacking is required. Me personally I’d add plywood to both sides to keep things symetrical. I’d use 1/2″ thick CDX plywood.

By: Fernando

Fernando — Mon, 26 Sep 2011 14:03:43 +0000

Todd,

Thank you for the reply.

Should I just add the plywood to one side of the joist, or both? Should I jack the joist, before screwing and gluing the plywood? What type of plywood should I be using?

Thank You