DaveW wrote:.... and put a course of bricks under it. I can still step over this easily, but it raises the door head height 3" and avoids the problem.
Exactly, Dave. The one and a half bricks I had above path and floor level (photo above on 29 Aug) gives just that extra clearance above the door to avoid grazing my bald patch
Tony Roberts
Treasurer, Haworthia Society
Chairman, Tephrocactus Study Group
Moderator, BCSS Forum
Kent
(Gasteria, Mammillaria, small Opuntia, Cleistocactus and Sempervivum are my current special interests)
I've always prefered to lay concrete bases for my greenhouses
(about 5 inches thick ontop of a damp proof membrane) I've never put one up before any other way.
The concrete slab is also raised above ground, and no water or dampness gets in - unless I put it in there when watering
I've finished my greenhouse, I will provide some pics soon. I have four railway sleepers providing the foundation for the aluminion GH frame. The floor is composed of a layer of sand, then damp proof membrane, then more sand, and then very large stone slabs rescued from a stone merchant as they are not in saleable condition. The cracks are all filled up with gravel.
The glass has all been sealed in from the inside with some Silicone gel (similar to stuff used in bathrooms) and most of the cracks filled up, and already it is dry as a bone in there!
I've just remembered I took a photo of my floor but never got round to posting it. My greenhouse walkway is sunken about 50cm or so (hence the concrete sides you can see) and the floor has black sheets of polythene covered with woven weed barrier which is very hard wearing. It's pierced in a few places for drainage. My logic is that such tiny holes don't allow for much release of water vapour into the air. This is one of the not very neat edges where you can see what's going on.
Phil Crewe, BCSS 38143. Mostly S. American cacti, esp. Lobivia, Sulcorebutia and little Opuntia
My GH floor is sunk below the level of the surrounding topsoil, but my damp-proof membrane comes up from the floor and is tacked (is that the right spelling? ) onto the railway sleepers, forming a complete seal so no damp can rise up from the soil. One corner has a small section cut out and the floor slopes towards it, so any excess or spilled water drains quite quickly to the corner and then quickly away
The glass has all been sealed in from the inside with some Silicone gel (similar to stuff used in bathrooms) and most of the cracks filled up, and already it is dry as a bone in there!
I was warned off using silicone gel by my local hardware supplier who pointed out that it will cause lots of broken glass when you need to take your greenhouse down because it will stick too well and your glass will get brittle. He suggested just using the foam and tape window sealers. I actually broke a few panes building my greenhouse because it was used and some of the glass had silicone on it that made the stacked panes stick together.
I didn't do either and was saved from having to redo it all this fall by moving continents and selling off my greenhouse.
True enough I guess, though I plan on being here for a long long time and it's easy enough to scrape off if have the knack and the right tool, and there is also a solvent that dissolves the stuff
) onto the railway sleepers, forming a complete seal so no damp can rise up from the soil. One corner has a small section cut out and the floor slopes towards it, so any excess or spilled water drains quite quickly to the corner and then quickly away 
and it's easy enough to scrape off if have the knack and the right tool, and there is also a solvent that dissolves the stuff 