i'm new, so bear with me & thanks in advance for any repiles.

a friend of mine has some leftover tounge & groove hardwood flooring (3/4" thick X 31/2" wide X random lengths - 24" min.)leftover that he would like to put on a section of a vaulted ceiling in a room over his garage. these would be attached perpendicular to the collar ties, wich are at 16" spacing.the area is approx. 28" wide by approx. 27'-0" long.

is it feasible to attach these directly to the collar ties, should we glue & screw plywood up first, or is this a bad idea overall. i'm concerned with sagging between the joists, as some pieces would only be attatched to one joist.

any ideas or opinionms are appreciated.