Being cold is bad, insulation is good, sometimes.  Periodically I find homeowners who will use white bead board insulation for ceiling tiles or as insulation in unfinished basement areas.  (This white insulation board is what cheap coolers are made of.)  This material is called expanded polystyrene .  This is safe to use only if it is covered with drywall or paneling, for burn protection.

When this expanded insulation catches fire it will create fumes that will knock us out, or keep us from waking up! 

This is a fire hazard and should be removed or covered with drywall.

Sometimes you will see a more dense insulation board used, that is often blue and a more dense material. This material is called extruded polystyrene.  This material has a fire retardant applied, but the manufacturers still call for it to be covered inside living areas.

Steve Vacha, Home Inspector

Home Standards Inspection Services,  Omaha, Ne