i am not an electrician but one code reference i found said that the
airspace (6 mm) applies to surfaces that might be wet a lot, or washed
down, such as would be found in dairies, commercial laundries, etc.

i've commonly seen metal boxes screwed directly into concrete block
basement walls, using pipe/conduit to carry the romex from above down
to the box.

don't know what a 'row home between the homes' is.

William Deans wrote:
Greetings,

The NEC states that you cannot put metalic boxes onto masonry which
may be
damp without a 1/4" airspace. Does this mean that you cannot use
metal
boxes / emt on masonry basement walls? What about metal boxes / emt
on
masonry basement walls of a row home between the homes?

Thank you for your time and energy,
William