Originally Posted By: kmcmahon This post was automatically imported from our archived forum.
What the heck is wrong with that? I see it all the time…a beam and column is nothing more than something to carry a load when you want open space underneath. Northing wrong with a bearing wall. Matter of fact, because it’s a bearing wall, the load is spread out every 16" instead of every 6 to 8 feet on columns. I see it all the time, and there is nothing wrong with that application.
Usually there may even be a small wall fooring under the slab, but it is not visible.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
mcyr wrote:
I am well aware of the IRC requirement, and personally, I would not want a dwelling built to that minimum specification.
A 2x4 wall is more that adequate to support a floor and floor above it.
Actually the IRC would not permit 2x4 studs for an interior bearing wall supporting two floors. That would be sub-standard construction even applying the minimum requirements of the IRC, which would require larger 2x6 studs spaced no more than 16" o.c.
The IRC has no tables/listings for interior bearing walls, which actually support more load than exterior walls (typically 1/2 the bldg width for interior walls supporting floors, as opposed to only 1/4 the bldg width for typical exterior walls). So for interior bearing walls you must use values for exterior walls plus the roof (IRC R602.4 & R602.3). It's a little light for the case of interior walls supporting two floors, but close enough.
Typical roof framing spans to the exterior walls, but if there is a posted or wall supported roof ridge down to a center bearing wall that also supports two floors, I would probably use 2x6 studs @ 12" o.c. in the basement to be safe.
Also, for wood bearing walls in a basement, make sure you look closely at the bottom sole plate ... it's a common place for deterioration to occur, especially if the basement or slab is damp.
JMO and 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: mcyr This post was automatically imported from our archived forum.
Hi. Bob;
Two moths ago I poured a structural slab for my Boss at his residence.
The slab was 21 feet wide by 35 feet long.
I formed it using TJI's that could later be used in the floor framing of the house and supported it with 2x4 studs at 12" o.c.. , every 4.5 feet.
Total weight estimated: 91,000 lb's
I don't think that two floors in a dwelling weighs that much.
I did not use books either, I used common sense.
I have heard that with the proper lateral bracing a 2"x4" stud could carry at least 3200 lbs.
The weight imposed on the studs I had came out to 520 lbs.
That is more that the 25% factor.
If a dwelling is two stories and all none load bearing the IRC say's that if you are supporting two floors, roof and ceiling, you need to frame at 16" centers for a 2x6 stud. one floor and roof and ceiling 16" centers for 2x4.
2x4 stud at 12" under 10' weight bearing of two floors and no roof load, not in book, what do you do now?
Consult a structural engineer. Most likely he will have you install a wood partition at 16" o.c. using 2x6 studs. Why? 25% safety factor, just in case.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
mcyr wrote:
Total weight estimated: 91,000 lb's ... I don't think that two floors in a dwelling weighs that much.
Residential loading is covered under IRC R301.4 - R301.6. You would be surprised at how quickly that adds up, and it probably would be close to that. Keep in mind that a basement center bearing wall supporting two floors will also need to support the ceiling at the top level.
mcyr wrote:
2x4 stud at 12" under 10' weight bearing of two floors and no roof load, not in book, what do you do now?
An engineered deign might be able to make that work, but it depends on the circumstances and factors that must be considered, which is well beyond a home inspection. The bottom line is that a wall with 2x4@12 has a lower capacity than the required 2x6@16 using the IRC as a guide ... so it gets flagged.
JMO and 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
