Friends of mine owned half of a Victorian duplex in a small town, and it worked out fine. The people who owned the other half were quiet and had lived there for years.

The previous owners of both sides had gotten together to paint the whole exterior at the same time, so both halves of the building matched and looked gorgeous.

Sometimes my friends could hear noise through the dividing wall, especially when people were going up and down the stairs, but that was the only negative. They were able to sell it easily when the time came.

When I was a renter I would seek out that arrangement, as I felt it made the best compromise between renting an apartment (affordable but noisy) and renting a house (quiet but expensive).

I suppose you could say its the same compromise proposition for ownership, however, I would be concerned that it would appreciate more slowly than a SFH. I'd research the price history of it and comparable properties and make sure its an investment you can live with. Yes, its more than an investment, its a home, but its still an investment too.

I think this is all good advice. My only experience with such a living arrangement was renting half of a duplex, where I lived for five years. I had three different neighbors over the course of the time I lived there. Two were elderly ladies who kept to themselves (as did the third person) and who were very quiet, except when they had family over, but that was to be expected. At one point I inquired about buying the whole building, but it was in a living trust and couldn't be sold, plus the price would have been out of my budget. I'd maybe talk to the owner on the other side, if you can, and see what he/she/they are like. You said you "don't really care for" the other side of the house Is there something wrong with it or its occupants?

It really depends where in the country the place is. In some areas of the country this type of arrangement is very common. In others it's not the norm at all. If it's in line with the area then the only draw back would be if the neighbor was a idjut who refused to do any maintance on his/her home.
You can not make someone do what they don't want to. Their lack of enthuasim for their dwelling could make it hard later on for you to sell. No one wants to live next to the worse looking house on the block.

We owned 1/2 of a side by side Victorian Painted Lady duplex for about 4 years. The other half was owned by the same guy for that period. During our "shared" ownership of the building, he used his half for his office and "city" home and ours was our primary residence. He was there during the day, we were home at night - great setup! There were a few occasions when he was there during the evenings and we heard sound thru the walls - the not so hot kind of like sounds you'd imagine hearing through the walls of a cheap motel.

During the 4 years, we had to have the exterior painted. He let us choose the colors and we split the cost - another great thing! We had to do some structural work to both of our back decks. He chose the contractor because he knew someone who would be low cost. I wouldn't have chosen the same fellow but the work was ok.

Our entire block was in a HOA for purposes only of snow removal, lawn maintenance and garbage removal. If we hadn't had the association, I am convinced we would have had problems getting our neighbor to cut his grass and shovel snow (we lived in Minnesota - snow is an issue). As it was, he was usually late on his association dues (due quarterly and he was often 1 yr late).

When we made the decision to move, we did a FSBO to this fellow. That was easy, too. However, if we stayed in that home, I think we would have ended up having problems because the house was getting close to needing some residing and bigger work. I think we would have ended up disagreeing on who'd be doing the work and this would have transferred into who was going to pay for it. Money would have been a problem. We got out, I think, in the nick of time but it was absolutely the right place for us to live during the 4 yrs we were there.

The next building over was also a side by side duplex and they ended up having huge disagreements over the needed repairs to their common flue and chimney. One owner couldn't afford repairs and the flue made the fireplaces unusable. Their friendship was hurt over that one.

Your internal upgrades should help you, but only if your shared owner keeps their side up. If you expect to have repairs to the common elements, I hope you get along and they are willing to share costs. Money is the only potential tough area that you'll likely encounter.