Cold Frames Finished

All four cold frames are finally finished and covered.

When Jeff and I were installing one of the frames, a rib broke. Of the 40 sticks that made up the ribs, to only have one of them brake is not too bad. It would be better, of course, if none of them had broken.


I thought about why this might have happened. The first two frames went up flawlessly. They were designed in large part because of the accidental breaking of the plywood when Jared and I drove it home from Lowe's. The larger of the two pieces had a minimum length of 49", so that was the length I followed. But for the two new pieces, I had Lowe's cut the length to be 48" (this cut the 8'x4' sheet exactly in half, two 4'x4' pieces). I did this so I could just put them inside the car. It avoided using the trailer. So my first thought was that loosing 2" on the length of the rib might have put more stress on the boards than they could handle. However, when I took out the lag bolts that held successfully installed ribs, they had already started to hold the curved shape they had been forced into, so the wood's flexibility was sufficient to accommodate this arc.

I think the better explanation was how this one board was installed. Each ribs is fastened with two lag bolts on either end connecting it to the frame of the raised bed. For all other ribs, I only put the upper lag bolt in first and put it in loosely, allowing the rib to flex a little while I started the second bolt. For this one, the first bolt went in tight. When we tried to put the second bolt in, it was difficult to find the lower hole and we pushed it too quickly. I think it stressed the rib too much and it snapped.

I replaced the broken rib (didn't lose any hardware in the process). Then I installed the fourth frame without incident. I had learned the lesson, so I proceeded slowly, leaving the top lag bolt loose until the lower lag bolt was in place.

I went to my office earlier in the day to finish constructing the cover. (The office has a large room where I can spread the plastic out, cut it to size, fold the edges and tape them, then put in grommets.)