I built my own cold frame, but it doesn't work because I go to work early and I can't stay home to adjust the lid during the day. You want an auto vent opener. I have a Bayliss MK7 and I like it a lot. Dan

I think these would work great for a cold frame. The function of a cold frame is for the structure to moderate temperatures and the glazing to let in light. In addition, having non-breakable glazing would be very nice. I say, go for it.

For a roof you can use polycarb panels but veggies don't grow much over the winer in zones 6 and 7. The days are too short and the heating bill will choke you. What do you plan to grow in it?

I've made my own coldframes from old sliding glass patio doors, old door hinges, scrap foamboard insulating sheathing, cedar 2 x 8's, angle steel from an old bedframe, and a solar powered vent opener. I made the cedar frames the size of the glass door, sloping it about 15 degrees, hinged the door on the high side, and installed the opener to the frame and then the door. The door is very heavy so I counter-weighted it by attaching the angles to the door hanging out from the door bout 2 feet and putting old cast iron window weights as a counter balance. I can lift the lid with one pinky now. The solar vent opener can now push the lid open but next time I'm just going to make vents in the front and back frame panels and have the opener operate them instead of trying to lift the door. I cut panels of foamboard to fit the interior sides and painted them white. I scrounged all the materials except fot the solar opener but I'm a retired building contractor and love building my own stuff. I like simplicity and easily obtained materials. Plans? I never found any, but check out the links above. Herbert