How to build a greenhouse
STEP 4. Erect the side walls and roof sections
Stand the two side walls upright on the base boards and support them with temporarily props. Fix the bottom plate of the side walls to the base with galvanized nails.
Lift the 5 roof sections in place on top of the side walls.
First position a roof section at each end of the side walls, and then position the other three evenly spaced in between.
Fix the roof frames to the side wall top plate with galvanized nails.
Temporarily prop the two end roof sections plumb (vertical).
Fix the 1 1/2" x 3 1/2" (90 mm x 45 mm) window support plate against the top of the rafter uprights. (See drawing 4c.)
Nail the 3/4" x 7 1/2" (190 mm x 19 mm) fascia board to the top ends of the long rafters as shown in the drawing,
making sure all the roof sections are vertical and parallel with each other.
Tuck some galvanized metal window flashing under and behind the fascia board prior to nailing the bottom of the board.
Brace the roof on the side that has no windows with two metal straps running diagonally across the top plane. Nail the straps at the ends and wherever they cross a rafter.