Plastic Covers for raised beds

I used 4 mil polyetheline plastic to make covers for my raised beds to delay the frost and freeze damage to my fall garden. I am planning to also use them and try and plant some of the early veggies and little earlier than normal this winter/spring. I did not think to take pics of the covers in place on the beds and I have already taken them apart and stored them for the winter. I did get some drawings of how they are made and how they are placed on the raised bed and held down.

I cut 8 foot pieces of 1" black flexible PVC pipe and placed them in the 1 1/2" PVC foundations in the beds to make the hoops for the plastic sheeting to rest on. I attached 1x2's along the top of the hoops with tie wraps to give the plastic sheet something to rest on and not sag between the hoops. The string is tied to each end of the bed and stretched and looped around each hoop further down for the same purpose.

These worked pretty well, but I had to remove them during the days that were warmer with lots of sun. The temperature inside at one point was 92 degrees and that was with the ourside temp reading 37 degrees. Putting the covers on each night before frost and taking them off in the morning before it warmed up was somewhat of a pain, but I did get about a month longer with not freeze damage.