Greenhouse from old windows - anyone built one?

My other half wants a greenhouse made from old windows. We've amassed quite a lot from craigslist and freecycle. I'd like to get it done this summer and have been researching it. So many methods that I'm not sure what to do. It will be roughly 6x10. Polycarbonate roof.

Floor.. Likely compacted gravel. Seen concrete and decking but think that's too much.

Stem wall or not? A few courses of cinder block/retaining wall blocks, or a pressure treated board resting on a few sunk cinder blocks.

I've seen ones fully framed with the windows mounted to the framing, and I've seen ones with just corner posts and headers with the windows screwed together to form the wall. Honestly, the hard part is going to be prepping the ground as it's clay soil that's mostly tree and bush roots that I'll have to dig up.

Has anyone built one? Any thoughts or suggestions would be appreciated.

A few random examples...

 

I have not built one (yet) but if it were me I'd build it framed and with a stem wall.

Stem: two reasons: one it reduces that ankle level condensation/green algae / time spent cleaning the glass. Two, it gives you a free kick panel so that you aren't bumping things against the glass.


Frame: Windows can and do break over time, and a wall frame makes an easier design for swapping individual panes. Plus as a bonus it opens up your options on mount points for hanging planters.


My two cents.