forwardly projecting t shaped board support 78 mounted on the lower stanchion member and a pair of forwardly projecting c shaped board supports 80 each mounted proximate a respective end of the upper stanchion member the elongate supporting base 26 is pivotally connected at the forward end thereof to the lower end of the lower stanchion member 22a so as to permit the stanchion to pivot about an axis which is transverse to the base as best seen in fig3 the base includes an elongate flat sill 27 having a series of keyhole shaped apertures 50 spaced therealong each of the apertures includes a circular portion 50a and a narrowed elongate channel portion 50b extending forward toward the stanchion the diagonal brace 30 includes a lower end which is pivotally connected to the rearward end of the base so as to pivot about an axis which is transverse to the base the upper end of the brace includes a pivot joint 46 positioned off center on the upper stanchion member 22b the pivot joint enables the brace and upper stanchion member to be pivotable with respect to each other about two mutually perpendicular axes of rotation the first axis corresponding to the longitudinal axis a fig2 of pivot pin 47 and the second axis corresponding to the longitudinal axis b fig1 of pivot post 48 either end of the upper stanchion member 22b can be telescopically engaged with the lower stanchion member 22a by inverting the upper member 22b about the pivot post 48 thereby increasing the range of roof pitch angles for which the frame assembly can be adapted for.