Every homesteader knows that a greenhouse is a great way to extend your growing season by protecting plants from harsh weather.
It creates a controlled environment for growing everything from vegetables to flowers, allowing you to grow year-round. Plus, it helps keep pests out and can save you money on buying produce.
So, I decided to build my own.
I’m building a 10×16-foot greenhouse using 2x4s and 4x4s, covered in plastic sheeting with a polycarbonate roof. I used standard-grade lumber and sealed it with a water-resistant stain.
Here’s how I built my own greenhouse and how you can make your own:
Tools and Materials
Before starting, make sure you have the necessary tools: a post-hole digger, a circular saw, a Sawzall, a drill, a hammer, a staple gun, post levels, a 4-foot level, silicone sealer, and pebbles for the floor. You’ll also need water sealer for the lumber and some basic materials:
Lumber:
- 2 x 16-foot 4x4s (mainframe)
- 2 x 12-foot 4x4s (additional support)
- 6 x 10-foot 4x4s (side frame supports)
- 1 x 16-foot 2×6 (crossbeam)
- 2 x 16-foot 2x4s (framing)
- 52 x 8-foot 2x4s (walls and roof)
- 4 x 8-foot 2x2s (smaller supports)
- 34 x 8-foot 1x2s (finishing touches)
Other materials:
- 300 x 3-inch wood screws
- 50 x 4-inch wood screws
- 3 bags of concrete
- 24 x 2×4 polycarbonate roof panels
- 72 x 1-inch lathe screws with rubber washers
- 1 roll of 40 x 50 feet 6 mil plastic sheeting
Construction Steps
1. Stake Out the Foundation:
Start by marking the perimeter of your greenhouse with a 16×10-foot rectangle. Use stakes at the four corners and one at the center of each 10-foot side to help guide the placement of the main support beams. Ensure the corners are square by using a string to measure the sides.
2. Dig Post Holes:
Dig six post holes, each about 2 feet deep, where your stakes are located. These will hold the vertical 4×4 support posts that form the structure of your greenhouse.
3. Position and Set the Posts:
Place the 10-foot 4×4 posts into the holes and support them with 3 to 4 inches of stone while adjusting them for alignment. Use a post level to make sure the posts are vertical. Once aligned, fill each hole with dry concrete and water it to form a thick slurry. Allow the concrete to set for 24 hours to ensure the posts are securely in place.
4. Install the Foundation Beams:
Attach 4×4 beams across the bottom of the structure, making sure they are level and positioned just above ground level to avoid direct contact with the soil. Add stones underneath the beams to support them and keep them dry.
5. Build the Walls:
For the walls, start by attaching two 16-foot 2x4s at the top and bottom of each side. Then, nail or screw in additional 2x4s spaced 24 inches apart. The 2-foot spacing is important for the roof, where you will attach polycarbonate roof panels. Assemble the walls with 3-inch screws, ensuring each joint is secure. Attach the walls to the 4×4 beams at the corners using 4-inch screws.
Related: How to Collect Rainwater Without Gutters
6. Construct the End Walls:
Next, build the two end walls. For the back end, measure and cut 2x4s to fit, with 12-inch spacing between them. For the second end wall, leave space for a window, ensuring the frame is sized accordingly. Install the end walls the same way as the side walls, attaching them securely to the 4×4 beams.
7. Install the Door Frame:
The front wall will include a door. The frame should be 6.5 feet high and 36 inches wide. Attach the door frame just as you did with the other walls, ensuring it fits securely within the 4×4 structure.
8. Attach the Top Beam and Cut the Posts:
Use metal wood braces to attach the top ridge beam to the corner posts. After securing the top beam, use a reciprocating saw to cut the corner posts flush with the tops of the side walls.
9. Build and Attach the Door:
Build the door frame using 2x2s and add a slanting brace for extra support. Attach the door to the frame with hinges and add a handle. For a tight seal, use door clips and window insulation tape around the edges to prevent drafts.
Related: 10 Household Items You Can Use as Mini-Greenhouses
10. Install Roof Rafters:
Cut four 2x4s at an angle and attach them to the roof ridge and the 4×4 posts at the corners. Use a water sealer on all the lumber before continuing. Stretch plastic sheeting around the sides of the greenhouse, stapling it securely. Once done, install 1×2 furring strips to hold the plastic in place.
11. Install the Roof Panels:
Attach polycarbonate roof panels to the rafters using lathe screws with rubber washers. Apply a long bead of silicone sealer along the rafter under each panel to create a watertight gasket. You can also use greenhouse tape to seal the seams where two panels meet.
12. Attach the Window and Final Touches:
Cut the plastic sheeting around the window opening and staple it to the frame. Install the window according to the manufacturer’s instructions. If desired, you can purchase metal roof ridges to finish the roof. Install these at the top of the roof and secure them with screws.
13. Add Flooring:
Finish the greenhouse by spreading stones or gravel on the floor to help with drainage and maintain a clean surface.
Once completed, you’ll have a fully functional greenhouse, ready for planting. Not only will it provide a controlled environment for year-round gardening, but it will also help you save money on produce and protect your plants from pests. Building your own greenhouse is a rewarding project that pays off with fresh, homegrown food year-round.
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