Last month, I wrote about Mistakes to Avoid When Putting New Plastic on Your Hoophouse.
Here are my recommendations on how to go about the task.
This job is best done in mild sunny weather, when the plastic will be dry and can stretch some but not too much. Arrange for a windless day to spread plastic – that is, less than 5mph winds, tops! If only breezy days are available, do the plastic spreading at dusk, when the wind drops. Or at dawn in summer, but not in cold weather.
Order the right size and type of plastic in good time. We use 48’ x 100’ Tufflite IV and Tufflite Dripless for our 30’ x 96’ gothic tunnel. Our plastic goes to the ground (no separate sidewalls). For the end walls we buy 24’ x 100’ for a double layer on each end. We use the wigglewire and aluminum channels (also called Polylock).
Get enough people committed. We like six people with good common sense, who are willing to take directions. It helps if some of them have done the job before. Consider having someone take photos of key stages, to make next time easier.
• Tall stepladder and 2 pairs of shorter stepladders
• Small-nosed pliers and a flat-bladed screwdriver for each person and a pair of bolt cutters (for the wigglewire)
• Tennis balls to tie into the edge of the plastic, and ropes to pull the plastic over the top. About 5 sets for a 96’ house. Use ropes long enough to go up and over to the other side – say 10’ longer than the width of your plastic.
• A sock and a plastic water bottle (to attach to the throwing end of the rope)
• Polypatch tape and scissors. Accidents will happen. Try to be gracious and forgiving!
• Utility knives to trim the plastic when you are completely sure it’s on right.
• For end walls, old drip-tape for battening (or buy actual batten tape, if you can’t get old drip tape), scissors, long staples and staple guns.
• For a 30’ x 96’ tunnel, at least 6 rolls of high quality duct tape. Stinginess doesn’t pay.
1. Turn off the electricity to the inflation blower.
2. Loosen just the ends of the wigglewire with pliers (and a screwdriver to ‘pick up’ the ends) all the way round.
3. If you are keeping the inner plastic and only replacing the outer piece, remove each piece of wigglewire, extract the outer plastic, then tack the center few wiggles of each wigglewire back in the channel to hold the inner plastic. If replacing both pieces, simply remove the wigglewires, but don’t lose them in the grass.
4. Pull off the old outer plastic, and either roll it up as it is, or cut it into 10’ wide lengths for future low tunnels. If you might want to use it to recover the hoophouse in an emergency, don’t cut it now. If the grass is damp, see #20.
5. Detach the blower and jumper hoses from the inner plastic.
6. Remove the inner plastic and roll it up, entire or in pieces.
7. Put new high-quality duct tape over all the metal frame connectors.
8. Unroll the new inner plastic outside the hoophouse along one side, keeping the surface which will be on the outside (top) dry. There are different opinions about whether the IR (Infrared Reflecting)/Condensate Control inner plastic has a right side and a wrong side. When we bought Warp’s Flex-o-glas inner plastic in 2003, they told us the treatment is throughout the plastic, not a coating, so it doesn’t matter which side is up.
9. Mark the center of the new inner plastic while it is still folded, to help with alignment. Or use any manufacturer’s writing on the plastic to keep plastic roughly straight.
10. Tie tennis balls in gathered-up plastic along the long edge which is on top of the unrolled but still folded plastic.
11. Tie a plastic water bottle in a sock to the free end of one of the ropes and throw it over the top of the hoophouse. Adjust the amount of water in the bottle to give a suitable weight.
12. Untie the socked water bottle on the far side, bring it back and repeat with each of the other ropes.
13. Agree with your crew on a set of instructions, especially to call “Stop!” if everyone should stop while a problem is fixed.
14. Slowly and evenly, pull the plastic up and over the top of the frame until the edge reaches the ground along the whole length on the far side. If the plastic gets snagged up on the framework, have someone (on a stepladder?) use the sweeping end of a broom or a SnoBrum on a telescoping pole if you have one, to lift and push the plastic free.
15. Start at one gable end on both sides and work in a coordinated way to the other end, shimmying the plastic around until it covers the whole frame and is square. You won’t want ripples and waves across your hoophouse.
16. Using the middles of lengths of wigglewire, tack the plastic into the channel, at least once every 12’ down the length of the hoophouse, on the baseboards (or the hip-board, if you have roll-up or drop-down sides). Don’t pull the plastic too tight.
17. When all seems good, work in pairs to attach your jumper hoses and inflation hose. You won’t be able to access the outside after you put the outer plastic on. Be sure to start with under-size holes in the plastic and stretch them to fit.
18. Refit your manometer now or later, before turning on the blower. If later, be sure not to cut the outer plastic when you make the hole for the tubing.
19. Unroll the outer plastic outside the hoophouse along one side, keeping the surface which will be on the inside (down) dry. If the grass is damp, use the old plastic as a carpet, and unroll the new plastic on top. You don’t want to trap moisture between the layers of plastic. Additionally, water between the layers will cause the two pieces to stick to each other and it will be hard to pull the second one over.
20. Mark the center of the new outer plastic while it is still folded, to help with alignment.
21. Repeat the tennis balls trick until the outer plastic is in position. It won’t have any metal framework to snag on. It should be easier. Make sure it can’t snag on the ends of the wigglewire sticking out from the baseboard.
22. Allowing a little slack, or at least pulling on the plastic only enough to avoid wrinkles, remove the wigglewires one at a time, put the outer plastic in place, and tack both layers in the channel with the middles of the wigglewires. Pulling the plastic too tight can result in the plastic rupturing in cold weather.
23. Using stepladders as needed, fit the plastic into the channels at one gable end, starting at the peak. An occasional little pleat is OK and will give you some slack. Your goal is a bubble 6-12” deep between the inflated layers, once it’s all done and running. Set the wigglewires fully, using pliers to grasp the wire ends and tuck them into the channel. Mark the ends of the wigglewires on the plastic as you go, using a really permanent marker, to make them easier to find when it’s time to replace the plastic (again).
24. Starting at the finished end, work down each side, doing the final setting of the wigglewires along the baseboards/hipboards. Trim the wigglewire if needed at the far end. If you are doing this with just two people, start at one end, fix 3 bays on one side, repeat on the opposite side, and continue switching from side to side. With two crews you can do both sides at once.
25. If you feel confidant, trim the plastic now, all the way round, leaving a 6-12” border. If you think there could be a problem that might involve resetting the plastic, leave it overnight.
26. Turn on the blower in the morning and check every few hours, adjusting the air intake as appropriate. (Best not to turn it on at night and leave it, in case you over-inflate and stress the plastic.)
27. Tidy up and write any helpful notes for next time.
Pam Dawling lives in Virginia at Twin Oaks Community, an egalitarian, secular, income-sharing, work-sharing ecovillage established in 1967. There she helps grow food for around 100 people on three and a half acres and provides training in sustainable vegetable production for community members, practicing farming with awareness of ecology, finite resources and the future of the planet. Pam is the author of Sustainable Market Farming. Read all of her MOTHER EARTH NEWS posts here.
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