Engineering Garage walls

I assume you mean no hold-downs, not hoedowns.

Is this your drawing? It seems to have disappeared from your post. If so, I believe you will need hold-downs for the short walls each side of the overhead door to connect to the foundation. You need to develop a moment connection at the bottom of each short wall.



EDIT: Foundation Plan and details added below.



BA

I am not sure if you saw the foundation plan, but those short walls are only 12" wide. Not sure we'd have enough space to accommodate two hold downs on each side. In your opinon, would you recommend sheathing whole structure w/ 1/2" cdx plywood and then placing the T1-11 over?

You could analyze the diaphragm as rigid so the front walls wouldn't need any shear. If the T-111 is adequate for shear, then you should be able to attach a holddown to the end chord. Depending on the lateral values, the long walls may not even need a holdown. Also depending on the lateral values, you may need to through bolt the holdown rod. If the T-111 is not adequate, you can install sheathing on the interior of the framing.

Those proportions for the diaphragm won't work as a 3 sided box by the numbers with wood roof sheathing. And the connections to the only shear wall in the one direction will be a bear to do as it's likely platform framed with a standard gable truss on top not designed for that level of load transfer.

I added the Foundation Plan and details to the previous post. I had not seen it until now.

Simpson Strong-Tie have a kit called Strong Wall for this purpose (see below), but a 12" width may not be adequate, particularly when the anchorage is missing at the foundation. You will need to retain a local engineer to recommend remedial measures to the foundation.



BA

Residential codes have standard impirical provisions and details for garage doors and minimums for the remaining walls immediately adjacent.

As others have said, your sidewalls don’t look meaty enough as is. Check the IRC to get an idea of proper proportioning.

CS-PF, CS-PFG, are the names from the Residential Braced Wall Section. APA also publishes a capacity for these portal frames (hence PF)