Brianna,
There is a line from the great movie "The Princess Bride" where Wesley says "Life is pain. Anyone who tells you otherwise is selling something." Navigating building regulations, constructing a house with integrity, and making a living at doing that are each a full time job that requires extensive investments of tools, time and experience to do right, so anyone who can speak with some knowledge on the subject is probably selling their time or a product. As such I would strongly urge you to continue educating yourself so you can at least see where the people you enlist to build for you are making their money, and whether their product is right for you.
Natural Building details vary a bit more geographically than industrial building details because generally more attention is given to climate appropriate design. The principles and skills and materials required to build a low chemical natural house are fairly straightforward, but demand is pretty low and the demand for industrial contractors is pretty high so very few of us can afford to tool up for and focus on building natural buildings despite our passion for them.
Most building regulations are broadly similar across the country, based on subtly different flavors of the same building code, with little regard (maybe even some latent hostility toward) climate appropriateness, chemical sensitivity or environmental footprint, There are also building regulations (like building size zoning rules and most trade licenses and insurance and banking and contractor relationships) that are particular to each specific town or county. Generally for a builder to make a living they will have to be licensed and insured to work in a particular town to build houses that meet that town's particular building code and insurance requirements in order for the client to get bank funding. Outside these norms your trail leads into metaphorical briar patches pretty quickly.
If you wanted a standard sized, bank sanctioned industrial chemical house you could find a contractor to build you something at least 1500 square feet in size for around $200 to $300 per square foot (before tariff craziness). My experience is that all of the most reliable industrial contractors will be very busy with a backlog of months or years. They will most likely not have the expertise to build a natural house or the time to talk to you about it. If they have time it might be to try to sell you something other than what you want--for that reason alone you need to educate yourself.
The demand for natural homes or low chemical homes is tiny, so finding a bank to loan money on one and a contractor to build one for you is a rare and beautiful thing. You may have to import that builder, which significantly boosts your costs. The locations that welcome tiny homes are few and far between, so often these tiny houses are built on trailers far away by specialty builders, most of whom do not have prior knowledge of the particular zoning and codes for your area, so they have to rely on you or a local contractor to tell them what the rules are there, or somehow charge you for the time it takes to find out, assuming we take the time to find out.
Many tiny homes get installed without local permissions, which is a risky but sometimes useful strategy. Technically there will be state wide building and septic and electric code requirements anywhere you go. Practically you will find pockets (mostly rural and impoverished) where the rules are not enforced consistently and you can do what you want. Somewhere you will find a contractor who can help you. Be patient and wary. Building code and zoning requirements you weren't expecting can be the death of your dreams. Building without approval is risky but so is a 30 year loan, and so is renting a house that is full of mold or chemicals that are wrecking your body and peace of mind. I go into that more here if you want to go down that rabbit hole
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The number of contractors who build homes that are code approved, low chemical, natural and tiny is vanishingly small, but not zero. Tiny homes are generally expensive per square foot--naturally tiny homes doubly so. I have seen many that are amazing little gems, but the road to success can be long. My building partners and I are based in Ohio but often travel as far as California or Washington or Idaho or Massachusetts or Virginia or Alabama to build natural buildings. It can cost a lot of money for the client and we don't get rich doing it, but it can be worth importing a builder or a building if it gets you what you need.
I'm sure this was not what you wanted to hear, but I am not trying to sell you anything. I would rather teach someone how to build something by doing it with them any day. That's my primary joy and I've done my time long enough to be a little choosy about my builds.
I wish for you to get the house you need. Please keep your head up. The fine people who are also replying here are mainly speaking kindly from experience.
--Uncle Mud (aka Chris McClellan)
