Pony wall on top of foundation wall

[akamike]

17' square addition to the corner of an existing house: The grade drops away a bit in this corner. Instead of bringing the concrete foundation wall up to the bottom of the first floor, the contractor wants to stop the concrete short and build a pony wall to support the floor. Pony wall would be about 2 feet high. Any concerns? Need to brace top of the concrete foundation wall? (It's in seismic design category D)
Thanks.

 

[concretemasonry]

Not good construction, but may be leagal according to the model codes.

Putting a horizontal hinge in the wall obviously decreases the lateral strength.

Dick

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

 

[MiketheEngineer]

As mentioned not the best idea - but done all the time. Make sure the new floor and roof diaphragm tie to the existing building well and you should be OK.

 

[msquared48]

And minimize the later pressure on the wall and knuckle joint created by the pony wall by not backfilling behind the wall in the crawlspace.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[JAE]

Mike - later, earlier or lateral?

 

[msquared48]

Good Catch. This was a partial lateral rapture of the mind.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask