Composite Illustrations by Nate Skow
In the first installment of this project, I covered the greenhouse’s general design, and the base and end wall construction. Plenty of work is still required to complete your greenhouse, so let’s get started. I have arbitrarily assigned the taller wall with the door and window in it as the front and the shorter solid wall as the rear.
Front wall framing
Lay an 8-foot 1-by-2 on the longest stud on one of the end wall frames (built in the first installment) and position one end ¾ inch (the smaller dimension of your 1-by-2) from the bottom edge of the end wall’s bottom plate. Mark the top end of the 1-by-2 on both edges beneath the side wall frame’s top plate and draw a line connecting the marks to pick up the angle. Cut this 1-by-2 on the line to make the first front-wall stud. Using this stud as a pattern, mark and cut five more studs (shown in red in Figure 1).
Take two fresh 8-foot-long 1-by-2s and mark them at 16 inches on center. One will be used for the front wall’s top plate and the other for the bottom plate (shown in blue in Figure 1). Cut a 31½-inch piece of 1-by-2 for the door header (shown in green in Figure 1). Screw the six red front wall studs to the blue bottom plate. Center your 30-inch door between the middle two – insert an approximately 3/8-inch-thick spacer between the door and the bottom plate.
Next, insert a 1-by-2 between the side of the door and an adjacent stud – be sure one end is snug against the bottom plate. Mark this 1-by-2 at the door’s top and cut it and another 1-by-2 to length. Remove the door (and spacer) and fasten these 1-by-2 trimmers (shown in yellow in Figure 1) to the inside of the studs on both sides of the door opening and install the 31½-long door header (shown in green in Figure 1, detail in Figure 2) on top of them. Now take a short piece of 1-by-2, set it on the door header’s upper surface and against one of the adjacent studs. Mark the 1-by-2 to match the stud’s angled end, cut to make a cripple stud (short studs placed between the header and top plate or between a sill and bottom plate; shown in orange in Figure 1) and screw it in place, centered above the door header.
Complete the front wall framing by attaching the top plate to the inside surface of the studs. Use a short 1-by-2 scrap positioned on the beveled end of the studs to ensure the top plate won’t interfere with the rafters (Figure 3).
Back wall framing
Lay an 8-foot 1-by-2 on the shortest stud in one of the end wall frames (built in the first installment) and position one end ¾ inch (the smaller dimension of your 1-by-2) from the bottom edge of the end wall’s bottom plate. Mark the top end of the 1-by-2 on both edges beneath the side wall frame’s top plate and draw a line connecting the marks to pick up the angle. Cut this 1-by-2 on the line to make the first back-wall stud. Using this stud as a pattern, mark and cut six more studs (shown in red in Figure 4).
Take two fresh 8-foot-long 1-by-2s and mark them at 16 inches on center. One will be used for the back wall’s top plate and the other for the bottom plate (shown in blue in Figure 4). Screw the seven back wall studs to the bottom plate as shown. Attach the top plate to the inside surface of the wall studs flush with their pointed ends as shown in Figure 5.
Assemble the wall frames to the floor
Fasten the front and back wall frames to the base with the bottom of the wall frames even with the bottom of the base using 3½-inch-long deck screws. Fasten the end wall frames to the base, and front and back wall frames using 1½-inch deck screws (as shown in Figure 6).
Mark the inside of all wall studs at 36 inches from the floor. Measure and cut lengths of 1-by-3 to fit inside the greenhouse and screw them to the frame with their upper edges on the marks as shown in purple (Figure 6). The 1-by-3 framing will support the shelving. Square up the front wall frame with 1-by-2 diagonals shown in yellow (Figure 7).
Next, construct the vent window frame by screwing two 527/8-inch-long 1-by-2s to one 13½-inch 1-by-2 and one 13½-inch 1-by-3 (as shown in Figure 8). Place the frame in one of the openings on the latch side of the door. Fasten two hinges on the underside of the window frame and the underside of the 1-by-3 shelf support (as shown in Figure 7). Install the vent opener to the top of the window frame following the manufacturer’s directions. You might need to position some blocking to complete this step.
Place the 4-by-8 piece of lattice on the support frame and cut it to fit (Figure 7). Fasten the lattice to the frame with No. 8 1¼-inch deck screws.
To create a surface for the door to seal against, measure and cut a piece of 1-by-2 that will extend from the outside of one trimmer to the outside of the other at the top of the door frame. Attach this to the inside of the frame so that it extends below the header ¾ of an inch. Measure, cut and install two 1-by-2s in a similar fashion on the inside surface of the trimmers.
Install your door following the manufacturer’s instructions. Don’t be surprised if you have to do a little trimming to get the door to fit, swing and latch correctly.
Assemble the rafters
Position a piece of 1-by-2 directly inside and along the top plate of one end frame and trace the bevel at both ends. Cut this and six others to make the rafters. Fasten two rafters (shown in blue in Figure 9) alongside the end frames’ top plates using No. 8 1½-inch deck screws.
Fasten the ends of the five interior rafters to the tops of front and back wall studs with 2-inch deck screws. Fasten a 1-by-2 8-foot-1½-inch long 1-by-2 fascia (shown in red in Figure 9) to the front ends of the rafters with 2-inch deck screws.
Cut 2 pieces of plastic (about 5 feet by 9 feet) that will cover the end frames generously. Staple (sparingly) the plastic to the frame, being careful not to stretch it so tightly that the frame is distorted. Leave the excess plastic for now.
Cut a piece of plastic about 9 feet by 20 feet. Mark the center of the 9-foot dimension every 3 or 4 feet along its length. Carefully tip the greenhouse onto its front. Center the bottom edge of the plastic on the bottom of the greenhouse with the edge covering about 5 inches of the bottom (skid must be removed). Staple at the center of the bottom edge of the plastic. Then adjust the plastic so the center marks are over the center stud and the center rafter. Staple at the top of the center rafter and then sparingly along the bottom edge.
Fasten a skid to the bottom with 3½-inch screws 1 foot apart and 2½ inches from the outer edge. Gently stretch the plastic over the greenhouse and staple onto the end frames, alternating sides to pull the plastic evenly. Tip the greenhouse in the other direction far enough to make the other bottom edge accessible. Gently stretch the plastic over the edge of the bottom and staple. Fasten the other skid to the bottom. Finish fastening the plastic; wrap it around the corners and staple on the end wall.
Staple batten tape around the perimeter of the end walls (Figure 10). Then carefully trim the excess plastic. Staple batten tape on both sides of the perimeter of the door and window. Slit the plastic along the outer edge of the door and window between the two sets of batten tape and add a slit for the door handle (see Figure 7).
Once completed, your greenhouse will supply years of service with minimal maintenance, and you can use it to extend your growing season at both ends. Since it’s mounted on skids, you can move the greenhouse around the yard or garden with relative ease, and slide it into your barn or shop for winter, or to replace the plastic and touch up the paint. My greenhouses have given me plenty of good growing. I know yours will, too.
In the Shop‘s “Small Garden Greenhouse Part 1” appeared in the May/June issue of GRIT.
An avid gardener and woodworker, Tom Larson combines these passions whenever possible. From his workshop in Sioux Falls, South Dakota, he produces lathe-turned bowls and vases, and from his garden comes beautiful organic produce.