Moving a greenhouse from there to here …

From here …
… to here!
If you google ‘moving a greenhouse’ you will find it a common theme. Practical advice suggests it is a straight forward task which can be accomplished in one long day – someone advises that with two people 12 hours is enough time to dismantle a greenhouse and reassemble it on a new site.
My experience is a little different. Although a simple task it required more time and, in assembly, considerable precision.
Taking down. There are two main jobs – removing the glass, and disassembling the structure. This greenhouse (“Solar” made by FAWT) uses bent aluminium clips and mastic to secure the glass, others use a combination of clips and foam strip.
Handling the glass requires gloves to protect and grip, and a tool may be required to free-up each pane. In my case clips needed to be bent back, and mastic needed separating from the frame. A long flexible knife will do the job. 
Aluminium clips holding glass against mastic and frame
tool for separating glass from mastic
The tool pictured here is not very flexible so careful handling is necessary to avoid cracking the glass. The mastic is hard when cold – it is easier to handle in warmer weather – and extremely sticky, so its advisable to gather loose bits before they stick to your shoes.  It is inevitable that a few panes of glass get broken, but mostly they are a standard size and replacements can be easily obtained from a local glass merchant. Cleaning the glass and scraping off old mastic is necessary before the rebuild process.
Much time will be wasted if you reassemble the stucture incorrectly. Find out if there are instructions available with pictures that identify the parts – some models may have these available online. There are two important aspects to these instructions – the identification of the parts (what goes where and in what orientation), and the sequence of assemble. Without instructions it is advisable to take pictures of all areas of the structure and perhaps mark or label parts to indicate relative position and orientation before taking it down. 
Clips and bolts and nuts are mostly standard, but there will always be some exceptions. Make a note of where the longer bolts and strange shaped clips are used. Also some spacers may be used around the corners. Carefully store all these bits because you will need every last one!
Transport. Glass is heavy and moving it requires a bit of care. I found the stack in the back of my car fell appart as soon as I came to a roundabout. The aluminium frame is light of course, and it is the pieces that go down the whole length of the structure that may limit the possiblities of transport.
Preparing the new site. The position for a greenhouse requires some consideration about orientation in relation to the sun and surrounding trees and building as well as the nature of ground surface on which it is placed. In full sun a greenhouse gets very hot. My garden has trees which shade the structure except in early morning – probably not ideal but OK for me as my main interest is in seedlings and young plants which need protecting against direct sunlight.
I managed to take the original set-up down by myself, but I could not imagine assembling it again in a true square fashion without help. I arranged for a Visiting Engineer to be present for the preparation and build phase. I expected to follow instructions about mounting the structure on prepared ground with concrete slabs.
The Visiting Engineer soon put me right about that! First – a flat area is not necessary, the important thing is that the corners are level. Second – after a ‘stress test’ done by hitting my paving slab with a hammer, slab was deemed unsuitable and a high density concrete block was used instead to support each corner.
slab after ‘stress test’
high density concrete block

Soil is compressible – depending on moisture content – so we dug out a small hole at each corner and replaced the soil with gravel on which to rest the blocks. This provided stability, and was also easy to manage when adjusting levels.

The four corners are made level, then the positions are confirmed by placing the greenhouse base on the blocks and ensuring the diagonals are of equal length. Holes are drilled and one side of the base is anchored to the concrete. The other sides are anchored later once some of the structure is in place.

Construction involved bolting together pieces (only finger tight at this stage) with the following stages –

  1. front (door) end
  2. back end
  3. the sides
  4. roof and roof window
  5. the door
  6. level and true-up (check verticals) and put (diagonal) tie bars in place
  7. glazing
  8. final true-up (squaring and level) and fixing – bolting down to remaining blocks. Tightening bolts.

A unanchored greenhouse can be lifted and moved by a gust of wind. Although firmly anchored to a concrete block at each corner, to be sure it would not lift we placed another block on top of each corner piece.

Glazing. On this greenhouse mastic and aluminium clips are used. As mastic is so messy it is necessary to start anew with this. Old mastic must be removed from the glass and the frame; new mastic must be purchased – this is in a ribbon strip on a large role. I also bought new clips. The old clips could have been reused, but they were mostly bent out of shape and covered in mastic. Although clips can be bought in DIY shops mastic in this form is not generally available – I had to go back to the manufacturer of the greenhouse to get a supply.

Thanks to the help of the Visiting Engineer the largest part of the construction was done within a day, but this was only after the preparation of the ground and the clean-up of the glass and frame which took another day.

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