Posted: 22/08/2012 at 19:27
Having made several cold frames the rules are simple. Back higher than front, sides sloping to fit back and front together and top window on good hinges plus overlapping the side and front slightly.
Depending on what pots you are putting in or even if planting into the soil as with a nursery bed depends on the height 12 inches back to 9 inches front or 18 inches back to 12 inches front it all depends on what you need. Four 2x2 inch corner stiffeners to fasten the side to with screws and a device to hold the lid open at various heights. Once sitting in position its own weight will hold it, more so with double glazing.
It should get plenty of light although South facing may be too hot, it needs a sheltered spot. and the thing to remember is at ground level with cover the soil will be a lot warmer inside than out, remember to water and open on warm days closing each night.
Hope this helps