wrote in message
White Styrofoam board is sold just like R5 extruded polystyrene board,
in the same manner, but is inferior in R value, workability and stability.

Where can we buy this "white Styrofoam board"? :-)

Nick

Styrofoam is the blue material extruded by Dow Chemical. Styrofoam is a
registered trademark of Dow but often the name is mis-used when referring to
any other type of polystyrene foam board, extruded or molded and wire cut
such as the CLOSED cell expandable polystyrene board, sometimes called bead
board.