Modifying a caterpillar tunnel part 3
PULLING the PLASTIC
With the help of a couple friends, guide the plastic over the ribs of your tunnel. We tie ropes around bunched handfuls of the plastic (or the plastic wrapped around a tennis ball or similar) in several places down an edge of the plastic. If your plastic is designed with an “inside” and and “outside” make sure you are pulling it over your tunnel in the proper orientation. Attach the other end of each rope to another round object. You’ll use this round object to throw the rope over the top of the frame. Your team will pull the ropes to bring the plastic over the top of the tunnel. I usually get up on a ladder inside the tunnel to help the plastic slip over the ridge. Sometimes it can get stuck. This process can seem intimidating, but once you do it you’ll become comfortable with the idea.
Next, step back and make sure there is enough plastic to cover the end walls on each end and check to make sure the length of the plastic on the sides seems even. Make adjustments if needed.
Repeat the process of pulling plastic over the tunnel for the second layer of plastic. Don’t forget to look for markings that indicate “inside” and “outside” of the plastic if applicable. Make adjustments if needed.
SECURE TO ONE END RIB
When things look even, begin with one end rib and secure the plastic to the wiggle wire channel. It’s a little work, but we’re able to use a single piece of wiggle wire and one channel to secure both layers of plastic.
ANCHOR THE SIDE WALLS
Then, we work from that end and we secure the plastic to the hip boards. We simultaneously pull the plastic down and towards the other (unattached) end of the tunnel. DO NOT simply pull the plastic down toward the ground. You must also pull it taught towards the other end wall. We alternate working on each side of the tunnel. We secure about 8ft worth of plastic on one side and then we switch to the other side and do that length. This way, we don’t accidentally skew the plastic. We’re paying attention and making adjustments as we go down the length of the tunnel.
REMOVE SLACK FROM RIDGE
Occasionally I’ll go up on the ladder at the other end and I’ll tug the plastic across the roofline to make sure we aren’t leaving slack between the ribs. Slack in the plastic is your enemy when building a semi-permanent greenhouse structure. If you have slack, the wind will batter that loose plastic sheeting against your ribs and it will wear through quickly and drastically shorten the life of your plastic. The plastic sheeting in the Farmer’s Friend kits should last at least 4 years.
ADD BLOWER KIT
The blower kit helps to insulate the tunnel structure by pumping warm air from the inside of your tunnel between the two layers of plastic to form an air cushion of insulation. This layer of insulation will help to reduce your energy expenditures.
We purchased our blower kit from Greenhouse Megastore. Here is the model. This kit requires hard wiring into an electrical system. It is not a “plug and play” model.
We bought some very sticky tape to help secure the tubing to the inner layer of plastic. Like this Flex Tape!
ADD JUMPER TUBES
Then, I added (this is very easy!) some “jumper” tubes so that the full sidewalls can inflate during the winter when the sidewalls are down and secured. I went to my local hardware store and just looked around for some flexible, non-perforated tubing that would allow me to connect the inflated roof area with the sidewalls. I used the Flex Tape to secure those tubes as best I could.
The inflation kit strength is adjustable with a simple louver system. You just rotate the fan cover to increase or inhibit airflow into the blower.
It is amazing how effective these small blowers are.
Let me know if you have any questions. Will share more of the “insides” of the tunnel next time.
