What a relief it was to get the end walls up and sturdy enough to go to the next step. The next step was to install the 2×4 joist hangers and mount the ridge board. The board that got mounted ended up being slightly bowed upward. I think it originally was sagging, but then when I redid the end framing, it got turned over and became a high spot.
Next was to build the rafters which were to connect to the ridge board. I used three kreg screws to join the two pieces together. One of the problems I encountered was the screws would strip out on me so sometimes it was only one or two screws holding the joint together. So that meant I needed to do the gussets. I had started making gussets when I was thinking about the greenhouse using 1” x 3” strapping, I am glad I gave up that idea. But I decided to use the gussets I had started making. I used a 2’ x 4’ luan board cut it in strips 24 inches long by about 7 1/2 inches wide, which would allow me to get 2 gussets out of each piece.
It is wise to make yourself a template to use as a guide, because you can get confused by all the angles here. I start with a 90 degree angle in one corner and all the other angles are 22.5 degrees, including the 90 degree angle on the other end, you never half to change your saw settings. This should be done with a miter saw. My 12 inch miter saw did not make a long enough cut for one of the angles, but if you move the piece around, you can complete the cut.
You attach the gussets to the rafters using 4 screws on each side of the joint and two gussets for each set of rafters, one on each side. Each rafter is composed of two 2×4s each piece cut at a 22.5 degree angle, trapezoid and not parallelogram style. The length of the bottom piece is 48 inches and the top piece is 47 1/4 inches to compensate for 1/2 of the with of the ridge board.
At this point everything is looking pretty good. There is some swaying the rafters which I need to address. I have decided to go with plastic covering as the rigid covering is going to cost $300 or more. More on this stuff in the next section of the blog.
List of Materials
6 – 2 inch x 4 inch x 48 inches long rafter, cut at 22.5 degree angle at $1.22 Each = $7.32
6 – 2 inch x 4 inch x 47 1/4 inches long rafter, cut at 22.5 degree angle at $1.22 Each = $7.32
96 – #8×3/4” Flat Head Wood Screws at $0.0399 Each = $3.83
1 – 2 foot x 4- foot x 5.2 mm Luan plywood at $6.25 Each = $6.25
36 – #8×2 1/2” Exterior Construction Screws at $0.0494 Each = $1.78
Total cost of assembling and installing the rafters = $26.50
So far total material costs are up to $203.56
Prices per Lowes. Price of 2×4’s is premium quality. Prices on these screws vary a lot, I am using galvanized exterior screws rather than the more expensive polymer coated screws, which cost about twice as much as the screws I am using. Some 2×4’s and the patio blocks were items I had on hand, so my actual costs are quite a bit lower than I am showing for buying all new materials.
-- Steve, Carmel, Maine, USA (near Bangor) (Hardiness Zone 5a)