> But concrete is pretty unfriendly to the environment and has a low expected lifespan reinforced concrete has low expected lifespan in exposed conditions beca

> But concrete is pretty unfriendly to the environment and has a low expected lifespan reinforced concrete has low expected lifespan in exposed conditions because moisture causes rust causes degradation. The concrete used for division between units, as being discussed here, is unreinforced. As long as there's no sulfate-containing minerals in the aggregate (and it's protected from moisture), an unreinforced concrete block wall will last indefinitely. Typical dividers in apartment buildings in the west are either concrete as I just described, or they are made with "steel studs" (C-channel with gypsum board). The latter is awful for noise isolation, while the former is okay (and better if some additional considerations are taken). Apartment buildings in my (north american) experience are built to the same standards as condos. The only time wood would be used in either is in a low rise (<4 storey) construction, which tend to not have any of the density benefits that you want from multi-unit construction, and all of the possible downsides.