My existing bathtub surround is tileboard. the bathtub is 5' long--the height of the tileboard above the tub is 5' . there are no seams except for the corners. I want to replace the tileboard but can only find 4'x8' sheets . The existing tileboard in my bathroom is clearly 5'x5'. I can not find anything but 4'x 8' . Does anyone know if 5' wide tileboard is still available ? 4x8 doesnt work without seams and a lot of waste. thanks