Welcome here bunny daddy. I edited your last post and removed the mention of your age. Minors are not permitted to post their exact age.
from the forum rules, https://binkybunny.com/FORUM/tabid/54/aft/10084/Default.aspx :
REQUIREMENTS:
You must be at least 13 years of age to become a member.
You must be 18 or older to post any photos of yourself. (posting photos of your rabbits, is of course, okay!)
Members under 18 cannot use their first and last name in their DISPLAY name, and cannot post their age.
At some point very soon, please click the link above and review these rules and guidelines.
As far as building plans, most people do NIC grids b/c they are relatively easy for people with limited or no building experience. Personally, I agree that they can look messy and unstable if not supported/attached correctly.
If your father is willing to assist with housing, that’s great! You mentioned having floors that can be hosed off, what are the floors going to be made of? I’m not sure how necessary it will be that they’re removable. People will usually just do tiles over the top (“peel and stick” that can be cut to size), or a solid piece of linoleum cut to size. Either of those options can be wiped down easily.
As far as wire, I would recommend rabbit wire, not chicken wire. Chicken wire is not strong enough to contain a determined bunny. Rabbit wire is designed to keep wild bunnies out of gardens, but in your situation it would keep your bunny in at night.
For the height you have planned with multiple levels, I’d also recommend a large hinged door on the front. You want to have full access to each and every level in order to clean and to retrieve your bunny if necessary. Maybe a hinged door for you to access, and also a small hinged “bunny door” on the bottom so your bun can get in and out the rest of the time.