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RE: Residential wood stud heights and stresses

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Regarding 2x stud bearing walls at exterior conditions:
Use caution when using 2x4 studs at exterior walls combined with an 
exterior insulating finish system (EIFS). If the walls are bowed due 
to studs that are twisted or crowned, the EIFS installer will not 
guarantee their work. 

The framer on one of my projects tried to notch the crooked studs
to adjacent straight studs, leaving several 6 foot sections of wall with


studs with 2 inches of stud at the mid height of the wall. (I had to 
make the framer replace the cut studs.)

As Dennis pointed out, 2x4 studs at `12 inches may calc, but its not 
worth the potential problems.

. If the framed 
walls do not meet the straightness required 
From:          "Dennis S. Wish" <wish(--nospam--at)cwia.com>
To:            <seaoc(--nospam--at)seaoc.org>
Subject:       RE: Residential wood stud heights and stresses
Date:          Sat, 14 Feb 1998 11:15:53 -0800
Reply-to:      seaoc(--nospam--at)seaoc.org

Tom, I not sure if I missed something but it sounds like you have 1303 plf
dead load (15psf floor load and 20 psf roof,including 30 feet of exterior
wall at 15 psf) and 704 plf live load assuming 16 psf at the roof for the
gable and 40 psf at the second floor.
The 2x4 is laterally braced so the only concern in the strong direction.
Without considering load duration at the roof, the studs when spaced at 16"
o/c appear to be overstressed by 25%. However, at 12" o/c they appear to
work.
The problem with cutouts is entirely different and I believe you are correct
here. Although, if you use a stud shoe such as the Simpson SS to reinforce
the stud, will you gain back any capacity you may have lost through the
cutout?
I assumed that the studs were laterally unbraced for 10' at the first floor
in the xx direction and constinously braced by virture of the sheathing both
sides in the yy direction.
Am I missing something?

One more note - how do you pick up the R19 value in a 2x4 exterior stud wall
without rigid insulation or is your area only required to have an R11
factor? In the desert, it is common to cover the outside face of studs or
over plywood with a rigid insulator (Powerwall) and then lath and stucco. I
am seeing less and less of this and more use of 2x6 framing with batt
insulation.

Dennis Wish PE


|-----Original Message-----
|From: HARRISENGR(--nospam--at)aol.com [mailto:HARRISENGR(--nospam--at)aol.com]
|Sent: Saturday, February 14, 1998 10:20 AM
|To: seaoc(--nospam--at)seaoc.org
|Subject: Residential wood stud heights and stresses
|
|
|      I would appreciate hearing what others do on 10' wood studs : 2 x 4
or 2
|x 6 , particularly in tract work.
|     '94 UBC table 23 I R 3 allows 2 x 4 up to 10' for a two story.
|     Section 2304 limits stresses.
|     Sec 2326.11.9 allows 25% notches (  7/8 " in 2x4 )
|     Sec 2326.11.10 allows 40% bores ( 1-3/8 " in 2x4 ) but must be some
|distance from a cut or notch ( 2" ? )
|      I am working on a tract with 10' first floor plates, 20' 2nd floor
joist
|spans ( no light weight concrete ) , and 38' roof truss spans ( heavy
tile ).
|Standard grade studs are overstressed without any holes or notches, No. 2
|grade studs is not common but they are overstressed if any bores or notches
|are added ( sec 2308 : flex plus axial ). With current electrical,
plumbing,
|telephone, cable, sound, vacuum, etc, requirements i don't see how this
could
|ever be within stress limits. Not to mention a HD8 in a 4 x 4 !
|      I am recommending 2 x 6 studs.
|      The architect and developer are bewildered that i even consider this
|when virtually all the tract houses in this area use 2 x 4 studs and it is
|allowed by table 23 I R 3.
|     When i consider this, i have in my mind the 2 story house in thousand
|oaks i evaluated after the Northridge earthquake ( 20 mi. away) that was
|similar and had almost every 2 x 4 stud on the first floor split and
|shattered.
|     Thanks in advance.
|
|     Tom Harris, SE
|     Thousand Oaks, CA
|
|
|



Philip Boultinghouse