With the price of building materials, and what you would have to pay contractors, the price will come out to be pretty close to equal, or above, of what you would pay for a home with all the space you need. You might want to rethink that option. These days, building costs are through the roof, just for materials.

What is your budget for adding on? And are you in a low or high COLA area?

Six years ago when I wanted an addition I hired an architect and told them my budget and what I needed/wanted. They gave me fairly detailed hand drawn ”design sketches” of 3 possibilities. I talked to the Contractor I wanted to use and gave him the 3 designs. He said only one design was doable with my budget. I said OK and had various meetings with the contractor over the next 8 months about what materials I wanted etc. Six weeks before he was to start he finally gave me a vague breakdown of what the costs would be. It was going to be twice my budget with no contingency. It would have been unfinished inside - ie no drywall. We did not go ahead with the addition.