Building manufacturer likely has no plans from 35-40 years back.....or even who may have built it...... and I have no idea who that gang was! They really don't even want to talk to private persons....but would rather shovel all of the liabilities off to the builder....who shovels them off to an eng/architect.....who then passes that cost to me.
It is frustrating to deal with all parts of this process. Mfg'er doesn't want to talk to the end customer, building construction company doesn't want to talk to the end customer, until they go to an eng/contractor to draw up plan$$$.
Concrete guys want plans.....even though they build similar buildings using the same practices for years...... 12-16" deep footing, 3-4'x 12-16" reinforcement at the upright supports, and 4-6" pad.
Getting an estimate from ANY of these groups is infuriating.....nothing but excuses and crickets. Who's on first? Wouldn't even give me the courtesy of a price per sq-ft estimate based upon present practices...... I guess business is too good......!
OK, I have proposed this as a new building, butted up to my existing to avoid the "addition" thing. Both local builders and the mfg'ers recommended this to avoid the "addition" thing where you would share a main upright etc and attach to each other accordingly.
So a "letter of (structural) determination" (IMHO) is a way the county is saving money by not hiring an actual engineer that could likely help with issues like mine. Pass the costs back to the tax payers. WE BE RUBBERSTAMPIN' SHITE ONLY...... Please forgive my rage...... They can also pass off any liabilities to the poor engineer should something happen.... (it has survived all the earthquakes around here for 40 years......already...)
.....AND, perhaps I am just over thinking it.
Steve