9 first flange 15 would be in registration with the bottom side 16 of adjoining supported board 2 and second and third flanges 19 and 21 would be in registration with the bottom side 16 of the next adjacent supported board 2 a number of alternate means may be employed in attaching the supported boards directly to the supporting members the most common system is illustrated in the drawings in which means 10 and 11 are nails which are toe nailed through edges 5 and 6 of first supported board 1 and means 18 are nails driven through edge 9 of adjoining supported boards 2 instead of toe nailing the supported boards may be attached by means of straps or ties the preferred form of the invention is illustrated in fig1 22 the connection consists of a plurality of supporting members 4 34 34 a first supported board 1 34 34 positioned transversely on the supporting members 4 34 34 having first and second side edges 5 34 34 and 6 34 34 and a bottom side 7 34 34 an adjoining supported board 2 34 34 positioned transversely on the supporting members 4 34 34 generally parallel to the.