Insulating a metal shop?

ESP47,
I know the head spinning thing!!!! Micro climates can likely play into the various discussions as well!!! That is my case here! 12 miles north and they have 20 degree higher days in the summer! South of me by 25 or so miles the temps can be up or down by 10-15 degrees.

15 miles as the vultures fly.....it's the Pacific ocean and the temp crazies it has! Cooling winds in the summer and warmer in the winter! Always with the humidity.....

In my case I am trying to control the humidity. Temps are easy.

In many of my readings, likely from the now below zero midwest....the advice is saying to seal seal seal. Isolate the steel members as they transmit cold and heat.
The idea being to keep heat and cold from ingressing. I would seal the cracks and gaps with a foam or pieces of insulation foamed in.....or such. Tape or foam the seams between material is always something recommended.

You're going to seal heat in and cold out part of the year, and heat out and cold in some of the year and the rest of the year it will be perfect!!! :) :) :) Any large gaps I would seal against birds.....and rodents.....with screen. My thinking came down to making a box that doesn't breath, inside a box that does. So the 3/4-1" gap between the tin and my ISO wall boards is for air flow "up" the walls and out the top with natural "as built" gaps. Let natural convection travel the air in the gaps, and circulate air inside the inner box with some sort of fan, electric or solar. I like the latter better! On with the sun, off with the dark! Just gotta find one..... That and a way to hang up a $300 65" SmartTV that I scored off of Craigslist from someone that was upgrading! Need purlin clamps.....

As for the ceiling, "barrier type" insulation is recommended to control the humidity. As this will also hold heat.....which now that your building is insulated, your cement pad will act as a giant temp regulator....will minimize heating your building! So I keep hearing "circulate" the air in the upper part of building to keep things regulated in a sense.... This makes sense to me...... A simple floor fan in the summer makes a difference with no insulation. In the winter it would serve to circulate warm air up high and mix it with cooler air down low..... A simple electric heater would suffice for where you are working at the time...... With the building sealed, that heat would be retained......eventually heating up and will be comfortable!

My dad had an old potbelly wood burning stove in his old wooden garage in MN...no where NEAR air tight or insulated....I recall going out in the morning to start the fire, coming back in the house for a while to let it heat up...and then going out and working in shirtsleeves! Nice melted snow/ice dripping down on you when you're sliding about on a creeper under the car......!!!

You are going to get high temps in the central valley....who knows in the winter! You get whatever blows in from the SF Golden Gate bridge pretty much and what rain blows in from north of the bridge!!!!

If you DO get super high temps that saturate the upper reaches of the building, you could still go with a solar powered exhaust fan on the peak or on and end vent location if you have such a thing. I put such a thing on our house in Santa Clara and it made an immediate difference! I can't put $$ numbers on anything but I noticed that it took longer for the house to heat up in the summer. In the winter it was to serve as a remover of humidity in the attic, which supposedly kept the house colder......not sure about all of that...... I had extended the fan wires to my roof crawl space door, and could just disconnect it by popping one connection loose. I need to check and see if it is still spinning!!!! Been a while....

I would "think" that your area would be less concerned about humidity.

As I was working near my 10' roll up door, I was surprised to feel a large cold breeze on my neck....... a quick look around revealed a HUGE 2-3
gap at my roll up door top! With the door closed! Called a roll up door company about a seal for this......but have not been able to follow thru due to holiday spousal madness.... I owe them some pictures...... Will see what they have to say.....other than some pumped up $$$$ bid to put it in..... I think I can manage that part.....!

Welcome to the circus!!!! I think you're on the right track!
Steve