Quote Originally Posted by Steve
Basically I will have a 15m by 5m concrete floor with breeze block walls and a steel roof (wriggly tin).
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Steve
Good grief, I am amature (well, that's no surprise then), I've only a quarter of that space to build mine in. Now seriously green with envy.

My advice: get floor really flat, level and smooth. Treat the surface with something that'll make keeping it clean easy. Do this as soon as it's weather tight.

2p .. Just about what my advice is worth