We have a three-season porch, not insulated, not over a foundation,
but watertight with windows all around. It currently has linoleum (or
vinyl sheet flooring, if that's what it's called today) on the floor
that has been there for 20 years. May I install new linoleum over it?
Or must I remove it?

If I put new over the old, I presume I would have to glue it down,
true?

Thanks.

BC
Floored