I have acquired a large greenhouse with a heavy galvanised steel
frame, made by Crittall Hope in Braintree, Essex around 1965. I've
found out a lot about Crittall (and Hope) on the net. I've also read
the recommendations for greenhouse bases, ie blocks, brick, treated
timber etc. I'm erecting it on a concrete base and the part of the
frame which rests on the ground has two lips, the outer one deeper
than the innner. Anyone seen anything like this before? I would like
to know what Crittall themselves recommended for the greenhouse to sit
on.

Rgds Mark