Construction of a Northern Cold Frame
The following step by step plans for building cold frames were prepared for a Yukon Secondary school .
The materials for the cold frame (along with 2013 costs) are listed below and illustrations are provided for each construction step.
The materials for the cold frame (along with 2013 costs) are listed below and illustrations are provided for each construction step.
Eleven steps have been outlined with related sketches designed to assist in construction of northern cold frames
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materials list (with count)
6 @ 2x8x14' spruce 3 @ 2x8x10' spruce 5 @ 2x4x14' 4@ 24"x1' 18 ga galvanized corners 3 @ 4'x8' coroplast 1 @ 16' x 10' 6 ml poly 2 @ 3'x16' geoteck fiber 1 @ 4" x 10' perforated PVC pipe 1 @ 4" 90 deg elbow 1 @ 4"x30" PVC pipe 18 @ 1"x2" x26" spruce 5 @ 3/4" EMT 10# @ 3 1/2" screws 4 @ 1"x4"x14' spruce 1 @ 12'x15' 11 ml greenhouse plastic |
Step 5 Tip the cold frame up, then line the bottom and all sides with the 6 ml poly. Staple the poly to the sides of the cold frame and poke two or three holes in the bottom of the poly liner. Then nail the four 1"x1"x26" pieces on top of the poly, spaced along the inside of the cold frame.
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Step 7 Place the perforated PVC pipe along the mid line of the bottom of the cold frame. Cap the open end and place a 90 deg elbow with the 30 inch section held vertically. Tie the vertical section in place. You may want to install a second 90 deg elbow to keep rain and soil out of the pipe. Install a salvaged 4" computer fan in the upper section of the pipe and wire the fan into a suitable adapter. Match the fan and adapter power output.
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an aside to describe how to make computer fan system
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Step 9 Fill the cold frame up to the top of the redi rods with cobbles that are 2" to 4" in diameter. This size allows the air to flow over the rocks while having a large surface area that permits them to warm quickly. Then place geotec fiber over the cobbles and fill the cold frame with top soil. You can screw 2x4x14 along the top of the cold frame side to provide a shelf for planting and tending the cold frame.
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Step 10 The frost cover is made from 11 ml clear poly, nylon fabric from Northern Green House Supplies. The frost cover is supported by a frame made from rebar covered by 3/4" poly pipe. The rebar needs to be covered so that it does not wear through the frost cover. The frost cover is sandwiched to the northern side of the cold frame using the 1"x4"x14'. The other side is sandwiched between the other two 1x4x14 's . This can the be placed over the rebar frame or removed quite easily.
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Step 11 All five of the 10' long sections of rebar are bent on a jig to ensure they are all the same shape. The frames are then covered with sections of poly 3/4 tubing, leaving the bends and the end 4" free. Half inch holes are drilled in the PWF 4x4 posts to accept the ends of the rebar frames. Three 14' sections of rebar are then covered with four sections of poly tubing sections about 41 inches long. These are then wired onto all the frames are the same bend. The tie wire is then covered by duct tape to protect the glazing from wear.
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Describe how to bend rebar
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