[Mikendebbie]

FRP will not do well in a horizontal application unless it is glued to something else. It wants to be glued to a wall vertically (like in a 7-11 bathroom). It has no inherent "structure" to allow it to span horizontally. It would break or crack quickly at every attachment point. Coroplast is like cardboard made of plastic. The internal corrugated guts along with the skin on two sides gives it some structure to be able to span horizontally and hold up at the attachment points. Those aluminum honeycomb panels that jeffba linked to are very nice - but get your check book out and make sure your pen has plenty of ink!