Sturdy but small greenhouse?

[tamsin]

I've an aluminium framed one (with corrugated plastic sides and perspex front panels) on my roof terrace that's been going 10+ years. It's actually sat on a wooden shelf (screwed the wall), so I can store pots in boxes underneath and then greenhouse itself is fixed the the wall at the back to keep it in place. I use a sheet of polystyrene in the bottom.