Minimum sizes for 2 & 3 story building

[WWTEng]

Is there anything in NDS or IBC that specifies the minmum wood stud size for a two story building? I am talking about a load bearing wall for a condo structure. For some reason I think it should 2x6 min.

Similarly, is there a code minimum size of cmu block for a 3 story condo building?

 

[woodman88]

Per the IBC 2009 Section 2303.1.1 which states that sawn lumber shall meet the requirements of DOC PS 20 for size and grade. You just design for a size that will work. Or you can look at the conventional light frame requirements which gives you Table 2308.9.1 for up to 10' stud heights. Which shows that a 2x4 will work at 16”oc. for a two story. For three story you need a 3x4 or 2x6 at 16”oc.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[focuseng]

Garth,
Is that the prescriptive design provisions? Don't have code handy right now.

MAP

 

[woodman88]

Section 2304 is the minimum standards and quality.
Section 2308 is the prescriptive design (conventional light frame).

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[concretemasonry]

There are hundreds of 6" CMU load-bearing apartment buildings (partially reinforced and partially grouted) built over 10 to 20 stories. They were all designed by SEs and very few items had to be noted by the SE for special like eliminating clean-out and using random video monitoring and no site sampling of units since they were pre-approved.

A three story building should not be a problem with either 6" or 8" walls depending on the floor system and floor plan.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[DST148]

Ref ACI 530-05 - There are no slenderness or minimum thickness requirements for engineered masonry.
There are slenderness limits and minimum thickness requirements for empirically designed masonry. The minimum thickness of bearing walls of one story buildings shall be 6". The minimum thickness of bearing walls of buildings more than one story high shall be 8". The minimum thickness of masonry shear walls, foundation walls, foundation piers, and parapet walls shall be 8".