The ceiling height nearly killed a $34k basement conversion
Bought a 1950s ranch for $265k with an FHA loan, 3.5 percent down. It had a walkout basement with its own door to the side yard, which is why I bought it instead of the cleaner house two streets over. Payment with taxes and insurance is $2,050.
I came from the trades so I did demo, framing, and all the finish work myself, and I hired out the electrical and the plumbing tie-in because I'm not licensed for either and my jurisdiction wouldn't have passed my work anyway. Permitted the whole thing. Rules on what makes a basement unit legal are local, so mine may say nothing about yours, and the building department was the first call I made rather than the last.
What almost killed it: ceiling height. The inspector wanted seven feet finished in the habitable rooms and I had 7 feet 1 inch to the bottom of the joists in most of it and 6 feet 8 inches under a duct run through the middle of the future bedroom. Rerouting that duct was $2,800 I hadn't planned and two weeks of nothing else happening. The egress window in the bedroom was another $4,100 with the cut and the well.
All in, $34,000 in materials and subs. My labor isn't in that number. It rents at $1,200 unfurnished, one bedroom, separate entrance, its own electric meter because the electrician talked me into the subpanel and second meter while the walls were open. Best $1,900 I spent.
So I'm at $850 a month for housing on a house I own, and the tenant is paying down my loan. I'd keep the permits and the second meter. Next time I measure to the bottom of every duct before I write the offer, not after.