Friday, March 25, 2011

Cold Frame Construction

Thanks for the question about construction.  It's good to know someone is reading this!  We (or rather, Tim) built a new cold frame top, to be added to the other one, expanding the size.  All of these frames are made to fit our framed beds, which are the same width, 3.5 feet.  The beds were framed with barn siding material, just because we had some on hand and we wanted to use what we had.

Before the wind storm, we had attached the cold frame with short pieces of pvc pipe placed over the ends of the hoops onto a grooved piece of wood attached to the bed frame, as shown at the right.

After the storm, Tim decided to bolt it to the side of the frame as on the left, with wing nuts on the inside.  It's a little more work to get it on and off for watering and tending, but not bad.  It was quite windy again last week, and the thing held on!

The plastic over the hoops is screwed on to the hoops with 1/4 round pieces of pvc piping (3/4" round).

Tim took the piping on his table saw and ripped it into 4 pieces, as shown.

In order to screw through the pvc and the plastic and the pipe hoops, Tim pre-drilled each hole, which helped a lot to keep the screws from slipping.

The end hoops have an additional 1/4 round piece of the pvc to hold the edge of the plastic in place, on both the frame and the door, as shown.  The door is screwed onto the ends of the hoops and opens out.  When closed, it is held up by two nails that go through holes in both the door and the frame.  (Not shown, sorry.)
Tim nailed these pieces of plywood on the sides to hold the sides of the plastic down.  I held and stretched the plastic while Tim screwed.
A shot of the whole deal, upside down. I think those are the highlights of the construction.   While stretching and screwing on the plastic, we kept the frame flat and kept checking the ends to keep the whole thing square.  Once we had the plastic screwed onto the ends, the whole thing stayed pretty square.

There are more pictures, but I think these give the main idea.  Here's a shot of the two, now placed together to give a 12' covered bed.

Tim has also made two more frames with hoops which we intend to cover with frost cloth to cover the most sensitive plants (peppers, tomatoes) just after planting in May.  There are always a few freezing or almost freezing nights that time of year, and hail!  We aren't sure yet if or how we will attach the frost cloth.  We may attempt a way to roll it over the hoops, so we can remove it and put it back again at will.  We're just not sure it will hold in the wind, unless we tack it down real good.

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