A polytunnels is a greenhouse that consists of a series of hoops with a polyvinyl plastic sheet covering. A greenhouse provides protection from harsh weather and a shelter and heat for seedlings to grow in. You can build your own polytunnel to grow vegetables and fruits that are out of season or not suitable to your climate. Once you have built your polytunnel you can plot out your garden and begin growing your own food.
Plot out the 3.6 by 12.6 m (12 by 42 foot) area on your property where you are going to build your polytunnel. At every 90 cm (3 feet) of the polytunnel plot drive two 45 cm (18 inch) long, 1.2 cm (1/2 inch) rebar stakes, 3.6 m (12 feet) apart with a mallet, leaving 15 cm (6 inches) of the rebar above ground.
Slide one PVC pipe onto the first pair of rebar stakes that are 3.6 m (12 feet) apart. Have a helper pull the top ends of the pipes down and hold them for you as you insert them into a coupling tee, with the top hole of the tee facing the interior of where the polytunnel will be, or towards the other rebar stakes. Secure the pipes and tee together by wrapping a generous amount of duct tape around the tee end and pipe where it enters it, taping 2.5 cm (1 inch) onto the pipe itself to make the first support ribbing hoop of the polytunnel.
Install the next two pipes onto the next pair of rebar and insert the cross connector with one of the top centre holes of the cross connector facing the direction of the first tee centre hole that you installed. Attach the pipes and cross connector assemblies with duct tape. Install the rest of the 3 m (10 foot) long PVC pipes the same way and place the other coupling tee at the other end of the PVC pipes, with the top hole facing in towards the pipes, not away from them.
Get your helper to hold the ladder for you as you insert a 90 cm (3 foot) long, 1.8 m (3/4 inch) lightweight metal electrical conduit into the centre cross connector holes of two neighbouring PVC pipe ribbing hoops. Affix with duct tape as before. Install all of the electrical conduit to create a top support cross bar for your polytunnel.
Insert the 5 by 15 cm (2 by 6 inch) boards on the ground against the PVC pipes, laying the first board so that its front extends out from the PVC ribbing hoops by 15 cm (6 inches). Place 1.8 cm (3/4 inch) conduit straps over the PVC pipes where they reach halfway up the board. Secure the straps by driving wood screws into them with an electric screw driver.
Set down a 5 by 10 cm (2 by 4 inch) in the entrance of the polytunnel so that its back long side is resting against the first pair of PVC pipes. Attach the metal framing anchor to the 5 by 10 cm (2 by 4 inch) and skirting by driving wood screws into them with an electric screw driver.
Make a frame with the 5 by 10 cm (2 by 4 inch) boards for the front entrance. Measure the height of the hoop ribbing, and if your 5 by 10 cm (2 by 4 inch) board is taller than this, cut it down to size with a reciprocating saw. Lay the boards on the ground and place another 1.8 m (6 foot) long 5 by 10 cm (2 by 4 inch) board at the top of them. Nail them together by driving nails diagonally through the top of the horizontal board.
Place a ladder on the ground at the entrance of the structure. Get your helper to hand you the 5 by 10 cm (2 by 4 inch) frame, and then hold the ladder steady as you place metal straps around the PVC pipes where they meet the wood frame. Attach the metal straps to the wood with screws using the electric screw driver.
Get your helper to pick up a 5 by 10 cm (2 by 4 inch) board and angle it up to the end of the right side of the door frame so that there is a 90 cm (3 foot) distance at the angle's widest point. Nail the top of the angled board to the top of the door frame. Do the same for the left hand side. Cut a 5 by 10 cm (2 by 4 inch) board to fit half way up the angled board between it and the door frame and nail the boards in place while your helper holds them up for you.
Tie a rope down both sides of the polytunnel. At the midway point of the rising sides of the PVC pipe hoops wrap the rope around them and make a square knot to secure the rope in place. Apply strips of polytunnel hot spot tape along the PVC pipe and metal conduit. With your helper, install the polytunnel covering over the hoop ribbing. Drape the bottom of the cover over the boards, stretch the cover taught and staple it in place onto the skirting.
Take care when handling power tools as they are dangerous.