Hey... I'm excited for your family and this new step! What a great opportunity.
We have a mortgage on our yurt! it was brutal... grueling 2 years and shaved a good 10 years off my lifespan... but we got it! I am genuinely proud of my bank for taking such a HUGE step with us and making headway for yurts in Canada.
Okay so main pointers like Jafo wrote... avoid using the term yurt for any reason. Its a house... that is a house... thats a permanent structure that 'happens' to look like a yurt... but its not. This was the KEY thing that finally got us over that obstacle that kept canning our request.
Our Yurt is on a post foundation (which I don't regret one bit), however post foundations=cottage=run around with financing options. So not only do cottages have the run around... we had a YURT on posts... but once the paperwork read 'cottage' and they could review the rest they realized as a cottage its extremely well built and a better investment than the average cottage.
This brings me to my second point. If at all possible... build a cement foundation. I don't know about how the US banks do mortgages but ours literally start from the ground up... the foundation largely dictates IF they will even look at mortgaging or how much they will put up for it. We would have avoided HUGE amounts of run around if we had just gone with a cement foundation and quite honestly after all the materials were considered for the foundation we did... it would have been cheaper. (also think... infloor heating
Basically banks want to know you are not going to be able to pack up their investment one day (as is the general reason yurts exist... to be mobile) and walk away. So you are going to need to convey to them that it is in every respect a permanent structure and about as easy to dismantle and move as would a 1200 sq foot rancher.
The lack of fabric can only help your case. Banks have a hard time wrapping their head around fabric even though in the long run its more durable not prone to rot and easy to replace.
Location is also key. The more remote the location the harder it is for a bank to want to finance it... unless its an area that land is crazy over the top sought after.
You are going to want to find someone who is willing to insure your yurt and property before anything else... banks generally wont mortgage uninsured properties... I'm pretty sure this spans the Canada/US border. We have insurance
from an underwriter... im not gonna lie... it costs a fortune and theres only ONE place on this side of the country that will touch it.
Having permits and all that in place are huge... I had mine built professionally (before I met and married my carpenter foreman husband) and that was a good call. I had every licensed trade take care of their own thing. It ran up our overall cost of building and overall building a yurt wasn't necessarily a 'cheaper' way to go it ran about the same as building a new house... but cooler haha. That being said... don't underestimate how much it can be appraised for... esp if you can talk with the appraiser and explain whats in it and the overall benefits of a yurt... ours was appraised twice by a bank appraiser for 150k to start and only slightly less than that value by the province's property tax... appraiser... people (i have no idea what their title is... the ones that determine the value of the house for property tax amounts). The land here that isnt ocean front is (for a lack of a better term) value-less. So those amounts are based solely on our structure!
I live in Canada so it goes without saying that things are going to be different than the US... but its a jumping off point to be able to check with your bank. If I could do things differently I would have gone to the bank first to check what the dos and don'ts are... I was able to independently fund the yurt and went to the bank after the structure already existed and they basically had to just 'deal with it'... im not sure that i would have gone through with building it if i had visited them first... or if they would have just said no across the board... and they would have... going to them with a structure already in place was more of challenging their rules rather than them dictating them to me.
Hope this helps some too. Please keep us updated I'd love to hear about your journey!