Hi,

Looking for advice on a greenhouse I am looking to build in the sunniest (relative) spot in my London garden.

My garden is West facing, the patch is South facing and gets sun from 12:30 to 18:00 (5.5 hours). Last summer I grew cherry tomatoes and courgettes with fair success in this patch (birds got most of the cherry toms tbh). I got a bunch or large tomatoes which didn't ripen in time before the plants died at the end of the season (I didn't realise you could ripen them indoors).

I want to build a greenhouse on this spot to increase my success rate with tomatoes and other sun-lovers like peppers, cucumbers, squash and pumpkin.

Originally I was going to buy a 4 x 6 foot aluminium greenhouse as the space is awkwardly shaped and this is all I could find that would fit, but then I thought if I design and build my own I could make better use of the space and have a bigger greenhouse for the same money.

It's going to consist of a brick foundation (neighbours old driveway), wooden frame (scrap liberated from skips), kitchen flooring for floor (have this lying around) and a polycarbonate surface which I will need to source. The whole structure will be covered in polycarbonate as I don't want any wood exposed to the elements. See CAD drawing attached (dimensions in mm). I've got my brother visiting in Sept and he has some carpentry skills so planning to start work when he's over.

What I couldn't figure out how to get across in the drawing with my limited CAD skills is the panels A and B, I want the poly carbonate sheet at B to be fixed in place, and A to open upwards on hinges, like a grow box, except a 1.6 meter high grow box = ). This should give me good access to all the plants as the space behind B will be quite large for me to be able to duck under.

So questions:

1. What thickness polycarbonate and how many chambers is usual for greenhouses?
2. Does the pitch of the roof look OK? Is this important?
3. Will leaving the door open (A) occasionally be enough for ventilation purposes?
4. Does the design look practical?
5. Is it worth the effort considering limited access to sunlight?

BTW I will growing plants in self watering containers as used by this guy: How Self-Watering Containers Work |

Any thoughts/comments appreciated.