[patoline]

Good Morning and forgive what I assume to be naïve questions. Here in earthquake country, I have a cavernous basement garage (12.5’ high, two stories above, support columns\posts in place) and I would like to build a storage loft.

First question: Can I use the existing columns\posts to secure the header boards for the loft? Or is that something to be avoided?

Second question: Assuming I can use the existing two columns, can the headers be overlapped on the front and back of the middle column as the two columns are not aligned?

I will attach a simple sketch (not in scale) so this makes more sense. Ledger board and headers are shown in red; the header on the left will be supported by a 6’ foundation wall.

Thanks in advance and please let me know if more information is needed.

 

[Daniel Holzman]

Adding a loft will add dead load (the framing) plus live load (whatever you plan to store up there). Based on your plan, you intend to transmit the load through the posts to the footers (assuming you have footers) supporting the posts. I cannot tell from the diagram how you plan to attach the ledger at the top of your drawing.

Whether you can do this plan or not depends on whether you are code compliant, which can only be determined by your local code official. If no permit is required, then the main consideration is whether the structural elements can support the load. That depends on the dimensions of the various pieces, how they are attached to each other, and the amount and distribution of the new load.

You say you are in earthquake country, so you need to determine the design earthquake load. Earthquakes shake the ground, and can exert large lateral (horizontal) loads on the structure. This can cause posts to buckle, joints to fail, and various other unfortunate effects. To resist earthquakes, you typically need a stronger design than in non-earthquake country, better connections, and more bracing. This is typically designed by an engineer or architect familiar with local codes and local earthquake conditions. Not something you can generally get off an internet chat forum.

Recommendation: Start by talking to your local code official about the design. They may require a stamped plan due to earthquake issues, in which case you have little choice but to hire a professional. Or the local code official may offer guidance on how to best construct. Best of luck with the project.

 

[patoline]

Thanks for your advise. The back wall of the garage is all concrete, part of the foundation. I was going to attach the ledger board with expansion bolts (work I have done before).

Will probably talk to local code person but may also go with a more conventional loft design and install posts independent of the existing support columns.

Thanks again