I bought a 30 by 48 last November for $500. It was only the frame and endwalls. I had to take it all down too.

This is what I learned from my experience. It sounds like you have a good understanding of what needs to happen.

1. How is the film attached? Board and batten is going to make it hard to reuse the film. (Is it possible to ever take the film off and put it on?)

Yes it is possible to take it off and reuse it. The holesf from the boards won't line up, but ask how long the plastic has been on it. If it were me. I would reuse it if is less than 2 years old, 3 or more, better just put on new. Most films are 4 year films. They can last longer. Keep the film and use it for other thing inside the greenhouse.

2. Foundation system. Posts or poured concrete. Getting foundation elements out of concrete is a no start, so it means it had better be a brand I can still get those pieces for.

For me the ground posts were in concrete too. I had to cut them off with a recipricating saw. I priced new ground posts, and they were more than the building. I was able to find some really thick wall pipes steel pipes that slid into the original ground posts. I drove those in the ground, set the middle and corners in concrete, painted them to help prevent corrosion, and slid the other posts over them. Then I drilled a hole through both pipes, and attached the baseboard with a bolt through both pipes.

3. Make and model of greenhouse. Where can I get extra bits?

GOOD IDEA!

4. Condition of tubing. Corrosion. Check esp. the lower ends of the tubes where they meet the ground, and the bolts where pieces cross.

If it is galvanized, it should be good. Check the bolts. I reused all mine. You can get a lot of money wrapped up in having to buy all new ones.

5. How well did it go together? Any evidence of needing extra holes because parts didn't line up? Extra holes are places to check for corrosion?

Also measure everything before you take it down. TWICE! This is really helpful when rebuilding it. I did a good job of this and was putting screws back in screw holes and almost all my bolts lined up perfect.

0. Tools needed/desireable.

* Air compressor and impact wrench

* Cordless drill, robertson & phillips screwdriver tips.

* Paint pen for marking pieces. Or weatherproof labels and felt tip.

* Socket set and combo wrench set.

* Rope/bailing twine.

* Rhino clips.

Make sure you can get electricity to the location. Also, how about Ladders? Also a recipricating saw, if the endwalls are wood and extra blades. My endwalls were nailed together and the occasional screw. I pulled out the nails on one end, then gave up and cut them all at the other end Cutting was much faster, easier and safer!

1. On my assessment visit take many pictures. At the end of that, I want to be able to figure out how many of each kind of piece there are.

Why?

2. Print up a bunch of weatherproof labels with part names on them. (Bow, north; perlon; diagonal brace, bow brace, basket hanger...)

Don't waste your time doing this. If the labels fail, you are out of luck. Write on the pipes with sharpie. Number the bows from one end to the other. Write the N-E-S-W on each one. When you take the perlins down, write the bow number by the bolt hole. Also, any and all brackets, trace their outline. Don't worry about marking the brackets, most of them will be exactly the same. I did take all the bolts from one perlin and put them in a zip lock bag and numbered them.

3. Taking the film off:

* Unfasten at the endwalls.

* Unfasten at the edgesUsing somehting like the leevalley rhino clips attach a line every 12 feet to one edge, throw the lines over the frame.

I wouldn't do this. Take the ends off, then take one side off, pull it over from the other side and then, once on the other side, take off the other sides

* One person pulls on the lines while the other watches for catches

* Once the cover is off, bunch together and tie every 4 feet much like a reefed sail.

Or take it out to a big grassy area and fold it up.

* Fold up the sausage as best you can.

4. Frame disassembly

Take down the endwalls first. Remove all baseboards or hip boards.

Then take down the all but one purlin. Take the highest one down first. You want to leave one on to keep the structure semi-ridged.

Remove all corner braces end braces. Remove anything else that is attached.

Remove last purlin.

My bows slid onto the ground posts. We just had to lift them up. Then we had a 39 foot bow to try and gently lay down and take apart.

5. Foundation: If on posts, I hope they have a tractor to pull the posts. Otherwise?

Ask what they want you to do. My previous owner was fine with cutting them off.

Here are some picture of my project.

Before
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North Wall Gone
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South Wall gone

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Baseboard and Purlins gone

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Sorry it was too dark to get a finished picture.

It took me 8 man hours to take it down. I did it by myself. I did have on helper with me to take the bows down that took about 30 minutes.

Good Luck!

Jay