Thanks, really good job you did there!Was fixed down, but only by a few concrete screw/bolts here and there.
I used corroline corrugated sheets. Not for everyone but I love how it looks and surprisingly seems an amazing acoustic barrier.
I did a thread on it here with photos at each stage https://www.diynot.com/diy/threads/another-man-cave-garden-room.594447/
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Still trying to get my head around how to tackle building off the slab.. Is your timber frame sitting in the blue bricks? What are the blocks I can see in photo? Ta!