Best way to stiffen I-joists
Best way to stiffen I-joists
(OP)
I am looking for the best way to stiffen I-joists to stop floor vibration. I have to use the minimum depth allowable by code for height reasons but realize the floor might feel too 'soft'.
Does anyone have any experience with this problem?





RE: Best way to stiffen I-joists
generic answers:
reseach manufactures web site for recommendations
Consider attaching with adding mid-span blocking
Screw (and glue) floor sheathing to I-joists
Enshure end of joists are secured from rotation
add additional joists
Sissor wood joist on I beams
use 3/4" 7 ply T&G A/C plywood
RE: Best way to stiffen I-joists
Floor has not been built yet and is still in design stage. It will be a multiple span length of 32' with the longest clear span of 20' below and 18' above. I would like to use the strongest 9.5" joist (BCI 6500 maybe ?).
But this span is far longer than product lit. recommends even though it is within code. We were dissapointed with the feel of a floor we just built that was within manufactures recommendation. (load deflection limited to L/480)
I will certainly glue and screw using 3/4" T&G. and will block at halfway or 1/3 - 2/3 mark. Other suggestion were box in joist with plywood one or both sides and use thicker T&G.
Obviously this will be a lot of extra work/cost which I do not want to do without knowing final result.
Do you think I am too far away from a stiff floor, to begin with, for some or all of these techniques to work?
Thanks for any help.
RE: Best way to stiffen I-joists
Consider using steel joists or beams.
RE: Best way to stiffen I-joists
It's max. span allowed by code is 20'8" @12" O.C.
RE: Best way to stiffen I-joists
RE: Best way to stiffen I-joists
RE: Best way to stiffen I-joists
You are correct about the right joist height, but I am trying to keep the height to a minimum to match the existing structure. If I use 11-7/8 I will lose height in first floor(already low ceilings) or have to make step up to 2nd from existing( my plan B). I am interested in your method to stop bounce in multiple spans is this widely used?
boo1
you say the other companies joists won't reach- do you think Boise Cascade are not being conservative enough with their data?
RE: Best way to stiffen I-joists
RE: Best way to stiffen I-joists
1-3/4 inches (45 mm) Flange: Cold formed Galvanized Steel
C-Joist, Floor System:
Size: 9-1/4 inches (235 mm) deep, 6-1/4 by 9 inches (159 by
229 mm) holes.
Minimum Delivered Thickness: 12 gage, 0.0966 inch (2.45 mm).
RE: Best way to stiffen I-joists
RE: Best way to stiffen I-joists
Paul