CustomDesignServices these are excellent questions. Hopefully someone with more knowledge on the subject can come along and help you out. I'm in Indiana, which has hot summers and cold winters, so I usually suggest spray foam if the customer is planning to climate control it, or reflective foil to help keep some heat and moisture out. They also have CondenStop or Dripstop, which is like a thick layer of felt that is rolled directly onto the sheet metal, which will prevent condensation, and if there are any leaks, it will absorb it.
CustomDesignServices spraying foam onto the interior side of the metal cladding sometimes voids the warranty from the metal building company.
Just make sure to read your contract. Every manufacturer I sell for has a clause stating that ANY modifications will void the warranty unless you get prior approval. For example, ACE Steel Carports will void your rust warranty if you were to install insulation or electrical, but they would allow you to retain your wind warranty on the anchors. Most companies don't do this and just void your warranty completely.
ACE Steel Carports:
ADVISEMENT: “ customer is advised that any modifications and/or alterations etc. made it to the structure without written design approval by Ace Steel Carports to avoid certain warranties. Alterations include, but are not limited to, electrical, plumbing, or aftermarket doors, shelving, or installation. Such changes to the design by the buyer could compromise the structure integrity of the building."
American Steel Carports
Any alterations to a building, such as adding shelves or electricity, or any modifications, will void all warranties. (Please refer to the back of the contract for more details.)
Eagle Carports:
4) ANY alterations done by the customer to the purchased unit voids all warranty items listed above.
I would ask your sales rep for a copy of their dealer book, which usually has warranty information in it, and of course, read the contract.