Can a Wood-Framed Wall Cantilever Over a Foundation Wall?

[Yankee Chronicler]

Where in the IBC or IRC does the term "sound engineering practice occur".

...

A design can comply with the code even if no calculations are provided.

The code doesn't use the term "sound engineering practice" but it does say the following:

1604.1 General. Building, structures and parts thereof shall be designed and constructed in accordance with strength design, load and resistance factor design, allowable stress design, empirical design or conventional construction methods, as permitted by the applicable material chapters and referenced standards.

1604.2 Strength. Buildings and other structures, and parts thereof, shall be designed and constructed to support safely the factored loads in load combinations defined in this code without exceeding the appropriate strength limit states for the materials of construction. Alternatively, buildings and other structures, and parts thereof, shall be designed and constructed to support safely the nominal loads in load combinations defined in this code without exceeding the appropriate specified allowable stresses for the materials of construction.

IMHO those two provisions pretty much encompass the concept of sound engineering practice.

If the drawings did not show the size and location of foundation elements, they are incomplete.

Agreed. And that was my point.

 

[tmurray]

Things I have done when I questioned the design of a structural engineer:

1. Ask the engineer some questions about the design
2. Request to see the calculations
3. Have the design and calculations reviewed by another engineer

If that checks out, permit gets issued. I've done #1 a fair amount. #2 and #3 very rarely. Normally, my concerns are addressed through a quick discussion. Sometimes I didn't understand something, sometimes there was an oversight by the engineer. Either way, a valuable conversation to have for both parties.

 

[Mark K]

The code doesn't use the term "sound engineering practice" but it does say the following:



IMHO those two provisions pretty much encompass the concept of sound engineering practice.



Agreed. And that was my point.

The code does require compliance with the code. Sound engineering practice may encompass things in addition to code compliance, but they are of no interest to the building official. The building code does not address all issues that an architect or engineer needs to consider.

The concept of sound engineering practice may be relevant if there is a question of legal liability, but questions of legal liability are resolved by the courts, not the building official.

Yes failure to comply with the code is considered negligence per say and can result in liability but the objective language in the code does not allow enforcement of what an individual believes is the intent.

 

[Yikes]

If the wall works structurally with with width that is in direct bearing, I would argue the rest of the stud is furring. The intent is to provide the required load path, If you only need 3 1/2" of the studs to work and you have 2x6 walls, you should be able to hang out 2" over the foundation wall.
But... the code does not explicitly say that. But... the AHJ can allow it if you provide sound engineering.

RedEyeFly has it right. If the code would accept a 2x4 structural stud wall+ sill plate directly over the foundation, and your could add another 2" nonstructural furred wall onto the stud wall to created the overhang, then what's the difference between that and just using 2x6 studs cantilevered 2"?
The DPOR could always provide a note on the detail indicating that 3.5" of the wall is intended to be loadbearing and the remaining 2" is for nonstructural aesthetic purposes only.

(Note, I am assuming that shear panel transfer of lateral loads, uplift, etc. is either shown in a calculation on the sill plate, or the shear panel goes on inside face of stud directly over the foundation, etc.).

 

[Paul Sweet]

Tim Murray said: "In Canadian code, the wall plates are permitted to project up to 1/3 the plate width. Note that this is 1/3 the actual plate width, not the required width."

There is a structural reason for this. The load from above is centered on the stud. If the stud overhangs the plate then then the load distribution of the plate is triangular with the maximum pressure at the outside of the foundation and the minimum at the inside edge of the plate. Once the center of the stud is outside the center 1/3 of the actual plate width then the inside of the plate is in tension. Additional anchor bolts near the inside face of the plate would be needed to resist this uplift.