What are the benefits and detractors for the standard cohousing model where you plan everything out then build it all then move in vs an alternative model of only selling lots to members and then people build their own houses?
Developing a community lot by lot isn’t the standard so much as the only way some communities could get started, both because of funding and because of the real estate expectations in some areas. In the early 1980s condominiums were still highly suspect in many small cities and particularly in rural areas.
I personally prefer the attached unit model and believe it makes the most sense economically, environmentally, socially, etc. One attachment to free standing homes arises from the desire for privacy. This is a serious concern. One way to address it is with the very best soundproofing materials you can find.
Amplified music, screaming children (and adults), game playing devices (weird repetitive noises), love in the afternoon (and night), cats rolling marbles overhead all day, widely varying sleep/stomping schedules, etc., are what drive people to the “give me space” options on both sides. It’s both the fear of being spontaneous and the fear of listening to others be spontaneous. Some sounds and people you get used to and others you don’t.
While I prefer attached dwellings, I still don’t like not being able to rearrange furniture at midnight or allow little feet to run around happily chasing each other. The pre-war buildings in Manhattan that were built of cast iron are still prized because there is absolutely no sound transfer from one unit to the next. And it is because of the cast iron.
Before researching this, I thought sound dampening came from soft surfaces. It does but only for reverberations inside a room. The important sound transfer stuff is the result of the density, or lack of density, in the construction materials that transfer sounds throughout the walls and floors. That two-year old running across my wood floor becomes a thundering elephant to my downstairs neighbor.
Cast iron is now prohibitively expensive unless you are building a huge building or a parking garage but there are other methods and materials that can be used.
Take sound transfer seriously and you can build the kind of buildings that will support a close, conveniently social, multi-generational community.