Some unforeseen costs for us included all of the accessories required to actually get our home set up. There were dozens of little things that we did not even think of before getting our house such as a sewer hose, a stand for the sewer hose, a heated water hose, a 50amp power cord, stairs, skirting for the winter, and many other small things.
We’ve seen some unexpected costs for the new tiny house on foundation on @shellmateisland. Some of the costs we didn’t account for were associated with meeting certain codes. The windows required by our county must be hurricane impact rated windows, which were 3 times the cost of typical windows. The materials needed to meet some of these codes can add up quickly. For the tiny house on wheels, the unforeseen costs include things like touch up paint and replacements for household hardware. This could be because of the high utilization—we use every bit of our house!
I think when it comes to the cost of building a tiny house, you just have to be aware that everything adds up. It’s impossible to budget out every single Home Depot trip as things you maybe thought would work (for example a certain type of drill bit) might not. There’s an extra $5. And it seems small but like I said, it adds up. So, when budgeting we would just recommend building in some buffer for those trips to your hardware store that you weren’t planning on.