How to Build an 8' Greenhouse
- 1). Measure and mark a 5- by 8-foot rectangle on the ground from the side of the house, using the house wall as one of the rectangle's 5-foot sides. Use spray paint for creating the lines of the rectangle.
- 2). Dig a narrow ditch along 3 sides of the rectangle, but not along the house. The ditch needs to be deep enough to accommodate an 8- by 8-inch piece of lumber for the greenhouse foundation. Lay 8- by 8-inch pressure-treated timbers in the trenches. Pressure-treated lumber lasts longer than regular timber. Make sure the timbers are level and the corners form 90-degree angles.
- 3). Frame the greenhouse walls using 2- by 2-inch lengths of spruce or cedar. Attach, horizontally, a 2- by 2-inch piece of lumber that is 5 feet long against the house wall at a height of 8 feet. Create the front wall frame directly opposite the 5-foot lumber piece on the house wall at a 6-foot height from ground level. This creates a roof pitch for water runoff. Set vertical framing studs at least 24 inches on center, but leave a 30-inch space between the front door studs. "On center" is a construction term that refers to the measurement of spacing for studs, rafters and joists from the center of one to the center of the next. If more understanding of how to frame a simple wall is needed, several easy-to-follow, step-by-step tutorials are available online.
- 4). Frame the greenhouse sides to the required pitch using 2- by 2-inch lumber. This requires that each vertical framing board be cut at a different height, in descending order from 8 feet to 6 feet in height. Once the walls are framed, attach 2 horizontal boards across the roof for support. The lean-to frame is now completed.
- 5). Staple 1/2-inch by 1/2-inch wire mesh to the roof. Staple 6-mil polyethylene plastic to the roof, on top of the mesh, and to the 3 framed sides. The back wall of the greenhouse is the existing structure. Overlap the plastic at the seams to provide a better air seal. The wire mesh adds support to the plastic and keeps it from sagging.
- 6). Install a greenhouse zipper door in the 30-inch front opening of the greenhouse, following the zipper door manufacturer's installation instructions.