How to Build Your Own DIY Backyard Greenhouse

2

Build the Foundation

• 2.1Use stakes and rope to mark out the contour.
• 2.2Place a concrete block (parts A1) in each corner of the greenhouse, under the door jambs, under the door threshold, and every 4’ between each block. Ensure that the blocks are positioned so that the foundation parts rest on the middle of the blocks.
• 2.3Level the concrete blocks once using a wooden plank and a level.
• 2.4Following the plan, build the wooden base (parts A2 and A3).
• 2.5Cut 2x4 scraps at a 45° angle to reinforce the corners (parts A4).
• 2.6Place the wooden base on the blocks, then level again. If a block is too high, tap it with a rubber mallet or remove some soil. If it’s too low, add some gravel and compact well.

3

Build the Front Wall

• 3.1Do not cut the crossbeams at this point.
• 3.2Place parts B2 and B3 together on their flat/wider side, then join them using screws.
• 3.3Next, lay the pieces that will make up the front wall structure (parts B1, B2, B3, and B4) on a flat surface and assemble them using treated wood screws, making sure that part B2 is located on the outside of the frame, and part B3 on the inside.
• 3.4Position the wall so that it’s aligned with the centre of the base (part A3) along its width and length.
• 3.5Secure to the foundation by adding a treated wood screw approximately every 12".
• 3.6Fasten the parts B5 to the inside of the uprights (parts B2) close to the door space, screwing from the outside to conceal the screws. These help reinforce the door structure.
• 3.7Place the lintel (part B6) on top of parts B5, then secure by screwing from above.
• 3.8Cut 2x4 scraps at a 45° angle to reinforce the top corners (parts B8).
• 3.9Using a chalk reel (or a sufficiently long plank of wood), draw a discreet line where the crossbeams (parts B7) will be installed.

5

Build the Side Walls

• 5.1Slide part D1 between parts C1 and B1, then screw into the base (part A2).
• 5.2Add the uprights (parts D2): 

  • The part D2 in the rear corner should be placed with the narrow side against part C1. Screw through part C1 to secure part D2.
  • The other 2 parts D2 (centre and front corner), should be placed with the narrow side towards the outside of the greenhouse and screwed at an angle into part D1.
• 5.3Slide part D3 onto the top of the side wall structure, then screw into the uprights (parts D2) from above.
• 5.4To cut the parts D4:

  • Mark one end 1" from the edge.
  • Draw a line from this point to the opposite corner of the other end.
  • Clamp the board to a workbench, then cut with a circular saw.
• 5.5Fasten part D4 in place (remember to leave the thin end of part D4 at the rear protruding by 8"), screwing from below every 12" or so.
• 5.6Repeat these steps for the second side wall.
• 5.7If necessary, add screws to securely join the front, rear, and side walls.
• 5.8Using a table saw, cut a 5/4x6 board in half lengthways to create part D5.
• 5.9Secure finishing parts D5 and D6 to the outside of the greenhouse using treated wood screws.
• 5.10Inside the greenhouse:

  • Cut 2x4 scraps at a 45° angle to reinforce the bottom corners (parts D10).
  • Add the window jambs (parts D7), then the top frames (parts D9), rails (parts D8), and reinforcements (parts D10).

6

Add Crossbeams

• 6.1Measure the space between the uprights at the level of the lines drawn to determine the exact length of the crossbeams (parts B7 and C3), then cut the boards to size.
• 6.2Measure again before cutting any other pieces.
• 6.3Fasten the crossbeams (parts B7 and C3) to the uprights (parts B3 and C2), checking regularly that everything is level. Where possible, screw through the uprights; otherwise, screw at an angle.

7

Build the Roof

• 7.1Following the plan, measure and cut the boards that will form the rafters (parts E1).
• 7.2Screwing at a 45° angle, starting at the ends, attach the 7 rafters (parts E1) to the top beam of the front wall (part B4) and rear wall (part C1). We recommend aligning the crossbeams (parts E1) with the uprights of the front wall (parts B3) and rear wall (parts C2), where possible.
• 7.3Make sure all parts are square before screwing into place.
• 7.4Using a chalk reel (or a sufficiently long piece of wood), draw a line where the crossbeams (parts E2) will be installed.
• 7.5Measure the space between the uprights at the height of the lines marked to find out the exact length of the crossbeams (parts E2), then cut the boards to size.
• 7.6Measure again before cutting any other pieces.
• 7.7Fasten the crossbeams (parts E2) to the rafters (parts E1), checking that everything is square. Where possible, screw through the rafters; otherwise, screw at an angle.
• 7.8Secure the roof by screwing parts E3 to the inside of the side walls.

9

Install the Clear Panels

• 9.1Using a table saw, cut PVC panels to size, as required (e.g., for windows).
• 9.2Using a permanent marker, mark all screw locations directly on the panels—in each corrugation "hollow”—at the height of each horizontal wood board (i.e., the top and bottom beams, as well as the crossbeams).
• 9.3Pre-drill each hole with a bit slightly larger than the hexagon-head screws. This looseness will prevent the plastic from cracking as the wood expands and contracts.
• 9.4Following the plan, screw the panels onto the front (don’t forget to leave space for the door!) and rear walls, then onto the roof, taking care to overlap the panels slightly (one wave) so that water doesn’t enter the greenhouse when it rains.

Use Your Garden Greenhouse Like a Pro!