[Matt W]

Recycled Materials.

I think CraigD6er is right. The "chrome" could be the materials that have been used to REPAIR the buildings. I suspect there wouldn't be much need for NEW buildings

For example, if the apocalypse involved nuclear weapons, there would be a lot of broken windows. I would expect that window glass would become a valuable trade good - and you wouldn't see single-pane windows. A window might be made from multiple/small pieces of glass (held together by wood,or lead). If there is no glass, old plastic bottles could be recycled as a useful (semi-transparent) building material. Or, if you want to be organic, horn or skin from mutant animals.

Older heating methods might be necessary (no electric heating) but open fireplaces are not possible when there's no chimney. Therefore, you might see the construction of pot-bellied stoves and similar techniques. A chimney made from old car exhausts...

Ambitious communities might have "new" types of street lighting. This could be as primitive as oil lanterns hung from the original street lights.