What does "$85 a foot all in" actually include?

Your instinct about the kitchen is right in a way that matters. Per square foot pricing works reasonably for things that scale with area, like flooring, paint, and drywall. It breaks down on kitchens, baths, and mechanical systems, because those cost roughly the same in a small house as a big one. A 1,600 foot house with two baths and a 1,600 foot house with one bath are very different jobs at the same square footage.

So a per foot number is a rough opening estimate. It is not a bid. A bid has quantities and line items, and it tells you what is excluded.

Questions for Thursday, in order:

What is excluded? Permits, appliances, and any structural or roof work are the usual exclusions, and "all in" said out loud is not the same as an exclusions list written down.

What are the allowances? An allowance is a placeholder dollar amount for something not picked yet, like cabinets or plumbing fixtures. If the allowance is $8,000 and your friend picks $14,000 of cabinets, he pays the difference. So he needs to see each allowance and go look at what it actually buys.

What's the schedule and what happens if it slips?

If the answer to any of those is a shrug, the $136,000 isn't a number yet.

Adding one. Ask who is pulling the permits and whether that person's license is current. Licensing rules and what triggers them differ by state, and in some places the license has to be held by whoever pulls, so your friend should call the local building department and confirm what they require before Thursday.

Also have him ask for proof of general liability and workers comp, sent from the insurance agent directly rather than a photo of a certificate. That one takes a phone call and has saved people a lot.