I'm not sure what you're describing but a traditional row house doesn't share any elements or living space. It's on a small rectangular lot facing the street and has its own walls that directly about the walls of houses on each side with no setback. Shared space like the street and sidewalk are owned by the city.

(Edit: there are also of course row house duplexes that would share a roof, front stairs, etc... But many are single family homes).

The only row house's I know of share side walls. Because they're all built in a row.

If you look closely when walking around a neighborhood of row houses you'll find that they don't actually share side walls. Each row house has its own exterior walls with siding / exterior finish that may end up directly adjacent to the next house's exterior wall. This is apparent in areas where one row house has been torn down or is larger than its neighbor. Of course sound and fire might travel through these more easily but they share no structural elements.

For an example of what I mean, take a look at SF's Outer Sunset district on street view.

Edit: it's possible that terminology and construction methods vary a bit between cities so all I can say is that you can certainly build a row of houses that share no structural elements.

Those Sunset homes are detached single family homes - like you said, they don’t share any walls.

But SF has its own classification of “fully detached” which specifies a minimum space between homes.

https://thefrontsteps.com/2021/11/08/detached-home-san-franc...

Rowhouses typically share walls.

I would call those townhouses, it's probably just a regional thing.

The row houses I'm thinking about are in Philadelphia, and I think most other east coast cities. Occasionally you'll see one with the neighboring house(es) demolished, and there are usually remaining bricks from the missing house on the now exterior wall.

Has anyone built a new rowhouse, like those in Philly, since the end of WWII? Serious question. I don't think they are allowed anywhere in the US anymore. Existing ones are grandfathered in.

I just googled and found new rowhouses, and soon to be built ones in Philly. The style seems to be more modern, but the basic idea is the same.