"Dave" wrote in message

This is a warm ceiling bottom floor (two floor house). I am thinking of
covering
it with a few layers of paint and perhaps some ceiling wallpaper.

The lights is what is a problem. Maybe I should cut enough space or add a
an
empty space between the stryrofoam sheet and the concrete ceiling.

I've seen many types of stryfoam mouldings and sheets sold in stores so
what is
the big deal of not being able to leave it exposed or just painted.

Styrofoam is usually 1.0 pounds per cubic foot. It has a flame spread
rating that is considered too high to be left uncovered. It will not burn
unless the flame is supported by other material, but it will burn under
those conditions.

The moldings you see are made from recycled styrene material and are a much
higher density, thus a lower flame spread. They are usually used in lesser
amounts also. Please, they are different materials.

You asked for advice. I've been working with foam plastics for 37 years
(packaging, building products, aircraft products, pharmaceutical products)
so I have some idea what I'm talking about. I'd not do what you propose in
my house and I advise against doing it in yours. No recessed lighting in
foam.