Logosol M8 - Manual (Page 14)

Bottom joists
Cut 4 joists into lengths, approx.
45x120 mm, so that they are about 100
mm shorter than the fixing boards.
Centre each fixing board on a joist and
screw them to the joists so that they
become T-beams. Screw in zigzags
every 15th centimetre using 35mm
screws.
Place the T-beams on the bottom so
that the fixing boards touch the 20
mm line. They must not extend over
this line. If necessary, the T-beams
can be moved a couple of millimetres
sideways. Screw the T-beams to the
bottom by screwing through the fixing
boards using 35 mm screws. Screw in
zigzags in every second or third bottom
board, but shift the screw pattern on
the T-beams so that every bottom
board, including the two outermost
boards, are fastened with at least
two screws. Now you can remove the
temporary board, which was used for
keeping the bottom together.
The T-beams are screwed together.
The T-beams are screwed to the bottom.