Wall stud deflection 3

[FSS]

Here in Florida our new code now contains language taken from the International code limiting stud deflections due to lateral (i.e. wind) loads . Distinction is made between brittle and flexible finishes. If I consider stucco to be a brittle finish I am hard pressed to get a 2x4 framed wall to work for even single story applications. For those of you in other parts of country with higher wind speeds, how are you handling the deflection criteria?

 

[UcfSE]

Are you talking about the 2004 FBC? I'm looking at the draft version Table 1604.3. It shows L/240 for brittle finishes. That isn't that bad really. Plus you have footnote "f" that states you can multiply the wind load by 0.7 for deflection. Does it still not work? I'm in Orlando by the way.

 

[DaveAtkins]

Most wood frame buildings here in Wisconsin use 2 X 6 walls, in order to get enough insulation in them. So it is not a problem. But I have done some projects where 2 X 4's are used, and yes, it can be difficult to control deflection. I would follow UcfSE's advice. Also, make sure you are using the correct component and cladding load, based on a tributary area equal to the height of the stud times 1/3 the height of the stud.

DaveAtkins

 

[FSS]

Yep. Have taken 0.7 reduction and used appropriate area for getting C&C load. 2x4 SPF #2 just does not get you far with the L/240 limit.

 

[sda97]

Would one be able to take composite action from the wood sheathing to increase the moment of inertia? Nailing of the sheathing to the stud would need to be a consideration.

 

[DaveAtkins]

I believe you can use the OSB to create a "T" section. Keep in mind the stud, by itself, must resist the axial force and bending, because the OSB will have horizontal joints which are not tied together. But in between these horizontal joints, the OSB will stiffen the stud.

DaveAtkins

 

[UcfSE]

Sometimes building specs specify that you cannot use composite action when checking deflection. You should verify that if you can. Can you take the height of the sole plate and top plate out of the height of the stud? If you have done all your loads correct and everything and it still doesn't work just reduce the spacing. All you can do is all you can do.

 

[boo1]

Where can this draft version be viewed?

 

[UcfSE]

http://www2.iccsafe.org/2004_florida_codes/