Building a DIY Hoop House / Polytunnel
Building a DIY hoop house / polytunnel is a great way to extend your growing season, protect crops from harsh weather, and create a controlled environment for your plants. A hoop house is essentially a low-cost greenhouse made of flexible hoops (typically PVC, metal, or wood) covered with a clear plastic material. Here's a step-by-step guide to building a simple and effective DIY hoop house.
Materials Needed
Hoop Frame Material:
PVC pipes (e.g., 20mm or 25mm diameter water pipe) for flexibility and ease of use, or
Metal conduit pipes (for a stronger, more durable structure)
Covering:
6mm UV resistant polyethylene plastic sheeting
Base Frame:
Wooden boards (2” X 4” / 50mm X 100mm or similar) for the foundation frame
Rebar or Metal Stakes: For securing the PVC or metal pipes into the ground
Fasteners:
U-shaped clamps or zip ties to secure the PVC to the base frame
Clips or spring clamps for holding the plastic sheeting in place
Optional:
Door frame materials: Wooden boards and hinges to create an entry
End wall support: Additional PVC or wood for reinforcing the ends of the hoop house
Rope or bungee cords to tie down the plastic for extra security
Step-by-Step Instructions
Step 1: Choose the Location
Select a sunny, flat area with good drainage. Make sure there is enough space for the size of hoop house you want to build, leaving room around it for maintenance and access.
Step 2: Measure and Mark the Base
Determine the size of your hoop house. For example, a 3m wide by 6m long hoop house is a common size. Mark the area where the base frame will be placed.
Step 3: Build the Base Frame
Cut the wooden boards to the desired size to form a rectangular base.
Lay the boards on the ground and fasten them together with screws at the corners.
Optional: You can anchor the base frame into the ground with stakes or rebar to prevent it from shifting.
Step 4: Insert the Rebar Stakes (for PVC Frames)
Hammer 500-600mm long rebar stakes into the ground along the long sides of the base frame, about every 1-2m. Make sure they’re spaced evenly and driven in at least halfway.
These will serve as the anchor points for the PVC pipes.
Step 5: Create the Hoop Frame
Bend the PVC pipes into hoops, inserting the ends of each pipe over the rebar stakes on opposite sides of the frame. The pipes should form semi-circles, spanning from one side of the base to the other.
Repeat this process for each hoop, spacing them evenly along the length of the base (typically every 1-2m). Do not leave any bare rebar stakes.
For metal conduit pipes, you can use a pipe bender to form the hoops if necessary, then anchor the ends into the base frame.
Step 6: Reinforce the Structure
For added strength, run a length of PVC or metal pipe along the top center of the hoops, connecting each hoop at the peak. Secure this ridge pole with zip ties or clamps.
This will provide additional stability, especially in windy conditions.
Step 7: Cover the Hoop House with Plastic
Unroll the UV resistant polyethylene plastic sheeting over the hoops, leaving enough excess on each end to secure the plastic tightly.
Pull the plastic tight and attach it to the base frame using U-shaped clamps or staples. Make sure the plastic is smooth and free from wrinkles to avoid tearing.
Use spring clamps or clips to secure the plastic sheeting to the hoop frame at intervals, ensuring it stays taut.
Step 8: Secure the Ends of the Hoop House
To close off the ends, fold the plastic over the end hoops and secure it with more clamps or staples. You can reinforce the ends with additional PVC or wood for added support.
Optionally, create a door frame at one end. Cut an opening in the plastic, and install a simple frame using wood or PVC. Attach a door with hinges or sliders to provide access to the inside of the hoop house.
Step 9: Ventilation
To allow for ventilation, you can roll up the sides of the plastic sheeting on warmer days. Secure the rolled-up plastic with bungee cords or clips.
Alternatively, install simple vent flaps or windows in the end walls to improve airflow. Otherwise a galvanised steel mesh can be used instead of closing the door on warmer days.
Customisation and Upgrades
Automatic Ventilation: Install automatic vent openers or roll-up sides that can be easily adjusted for temperature control.
Heating: For colder climates, you can add a heat source such as small space heaters, or passive solar heating systems like thermal mass (e.g., water barrels). Consider energy costs for each solution.
Raised Beds Inside: Use raised garden beds or pots inside the hoop house to improve drainage and make planting more accessible.
Irrigation: Install drip irrigation systems to ensure consistent watering without increasing humidity levels too much, which can lead to fungal issues. Or consider options for watering from the bottom e.g., pots in trays.
Maintenance Tips
Tighten the plastic regularly: As temperature fluctuates, the plastic may loosen or stretch. Check and adjust it periodically to ensure it stays taut.
Watch for tears: Repair any small holes or tears in the plastic immediately using greenhouse tape or patches. This is easier in the warmer weather where the adhesive will be more tacky.
Seasonal adjustments: In very hot climates, consider adding shade cloth to protect plants from overheating.
Plastic lifespan: The plastic may need replacing in the future due to UV degradation and damage/wear.
Benefits of a DIY Hoop House
Cost-Effective: A hoop house is much cheaper to build than a traditional greenhouse.
Season Extension: You can grow crops earlier in the spring and later into the fall by protecting them from frost.
Weather Protection: Hoop houses shield plants from excessive rain, wind, and harsh sun.
Customizable: You can build a hoop house of any size to fit your garden space and needs.
By following these steps and customising the design to your preferences, you can build an efficient, durable, and affordable hoop house for your garden.
