Does anyone have experience or advice on converting a smallbarn/garage into a tiny house?
I'm sure this is kind of stupid but they don't have foundations right? Is it even worth trying to convert one into livable conditions?
My mother in law is moving soon and had the idea of buying a property with a barn to convert into a tiny house for us so exact specs are not known yet.
Converting a barn to a house could be a can of worms--bad foundation, no foundation, rot, leaks, no square angles--all sorts of things can cause a barn conversion to cost more and take longer than just building a new building, but the right barn, one with good bones and character, can be well worth the effort. Back in the day my new bride and I escaped at the end of college with less than $1000 debt largely by converting the attic of my Aunt's garage into a primitive but cozy love nest. For the cost of some drywall and insulation we got a place to stay and she got an extra finished room. Win-win.
Keep in mind that most places in the US don't allow two dwelling structures on one lot. One of my clients converted their big, beautiful barn (at great expense) into the primary dwelling unit, arranging permission to do so by removing the bathtub from the existing farmhouse to turn it into into the office for their business. You would most likely have to get a variance or find a "grandfathered" lot to legally turn the barn into a second house. You might find it allowable as an "in-law suite" or, if the property is still being used for farming the change from accessory building to cottage might be allowed as farm-hand housing.
If you're willing to go "outlaw" however, an existing barn is an excellent place to hide an illegal dwelling "in plain sight". A little bird told me that most of the people who would raise an eyebrow at a new cottage or tiny house "spoiling the neighborhood" won't even notice a new window or two in the back of an old barn. If you play it right you can use your barn to quietly collect your materials on the cheap and build as you have time. Craigslist and ReStore and dumpster finds take more time and ingenuity but save a lot of money.
Also, the same little birdie told me it is a very good idea to insulate insulate insulate. A drafty building with a cold concrete floor is uncomfortable and expensive to heat and you could find the existing electric wiring to the barn is good for lights but not enough to heat and cool the building. While you're going illegal anyway, consider a rocket mass heater to heat the space. A few tons of dirt and some stovepipe and you have almost free heat. Our uninsulated barn conversion in the upper Midwest cost over $350 to heat with electric some months, but less than $100 to heat for the year once we installed a RMH.
When running a water line to the building be sure it is deep enough to keep from freezing. A Jenkins-style composting toilet and greywater system are low cost alternatives to a septic system (if you can even get a permit to install a septic).
If you are building without zoning permission there is always a chance you will be found out, so it is important to keep your investment within what you can stand to lose if you lose the use of the building. At least with a barn you can always go back to it being a (new and improved) barn or workshop where a new building could be ordered removed. Best of luck in your adventure.
If you want inspiration, Shelter by Lloyd Kahn is one of my favorites. I have worn out six copies.