How to get good new home/ADU construction specifications?

[Bruce P.]

Hi BP community,

So my friend is spinning their wheels a bit. They are planning to put a detached ADU (accessory dwelling unit) on the property containing their SFH (single family home) in southern California. They already have architectural plans.

They are now writing detailed specifications to ensure they get what they want but also help any potential contractor bid correctly and reference the specifications in a SOW and/or contract.

They've been scouring various resources to help them.  It's easy enough to write specs for cosmetic materials (e.g., "The toilet shall be make / model # XYZ123 and be white in color"). But looking at some example specifications on the Internet for things like the foundation, they found clauses like this which seem important but which seem like they require a decent level of expertise (e.g., it would help you are a general contractor which my friend is not):

Joist framing. Joists framing into the side of a wood girder shall be supported by approved framing anchors or on ledger strips not less than nominal 2" x 2" (51 mm x 51 mm). (Section XYZ13.ABC IRC)

1) So the question is - what have you done to get the right level of detail in your specifications, especially for an ADU, which is a smaller building than a single family home but would probably require the same level of detail to be constructed and bid on correctly? Have you hired outside help? Since they're based in CA, it seems like you'd want to take extra care to ensure your building matches the appropriate state and local codes.

2) Also, is the level of detail in the "joist framing" example is too much for a specification intended to get an accurate bid from potential contractors and serve as a line item in a SOW contract?