Nonbearing wall floor support

[Mr. Inspector]

Can someone tell me what section of the IRC tells you about floor framing under nonbearing partition walls? I have someone that wants to put new nonbearing walls up and can't find anything in the IRC.

 

[JBI]

There are no specific provisions for floor framing under non-load-bearing walls in the IRC.
Common sense would place them directly over a joist if parallel, but 'common sense' is a bit of an oxymoron these days...

 

[Mr. Inspector]

I am required to specify a code section.

 

[mtlogcabin]

I am required to specify a code section.

You can't specify what is not written

 

[ICE]

How do you define a non-load bearing wall? Well that's a wall that supports nothing....no ceiling joist, no purlin brace....nothing. That's rare unless the building is all trusses.

There is a code for a bearing partition supported by floor joists. There isn't a code for non-bearing. However there is a conundrum of nailing a wall down.

Is it okay to nail the wall bottom plate to nothing more than floor sheathing?

What happens when a heavy clothes dresser is against the wall and it is mid-span between joists? The answer to that is deflection. I can't be trusted to do the right thing so I always ask for a pair of joists under partition walls that are parallel to the joists and double full depth blocking if the partitions are perpendicular to the joists.

R502.4 Joists under bearing partitions. Joists under parallel
bearing partitions shall be of adequate size to support the
load. Double joists, sized to adequately support the load, that
are separated to permit the installation of piping or vents shall
be full depth solid blocked with lumber not less than 2 inches
(51 mm) in nominal thickness spaced not more than 4 feet
(1219 mm) on center. Bearing partitions perpendicular to
joists shall not be offset from supporting girders, walls or partitions
more than the joist depth unless such joists are of sufficient
size to carry the additional load.

 

[Mr. Inspector]

This is in a existing house where they're want to add some nonloading walls on 2nd floor. Cieling is finished under floor and floor is finished. Would you make them open the floor to add a second joist under the new walls?

 

[JBI]

If you can't show them where it is required, you have no business requiring it as a Code Official.

 

[FLSTF01]

Let them build the walls-no code section requires anything different than what is in the floor joist span table for non-load bearing partitions.

 

[JBI]

A framed wall section weighs about 2 or 3 pounds per foot, the bedroom floor needs to support 30 per square foot. I think you have plenty of wiggle room for a dresser up against the wall (and the bulk of that dresser 'load' will be on the other side of the nearest joist anyway).