[rogerg (Roger)]

I've decided I'm going to line the inside of the enclosed half of my observatory (the half that the roof doesn't roll off).

I'm planning on using HardiFlex and just tech screwing it on to the walls, adding some extra beams such that there's a beam at least every 400mm. I'm thinking of using 4.5mm thick HardiFlex but might have to go to 6mm thick to get 3m lengths (which would nicely do an entire wall length-ways.

I'm going to do the walls and the roof.

Not sure on insulation - the wall cavity will only be 40mm, so insulation bats aren't applicable (too thick) as far as I'm aware. Not sure what option would suit. The rather un-helpful person at Bunnings yesterday suggested this "AirCell" stuff which was extremely expensive - something like $78/m!

I figure I'll then paint the HardiFlex some lightish colour.

I don't think I'll complicate the issue with putting power in for lights etc, will stick to free-standing lights.

Anyone got any advice I should have before I start? This will be the largest DIY job I've done, perhaps on par with building the observatory to start with, but that was just a case of screwing in hundreds of tech screws. This requires less time but a few different bits of knowledge I'm only just learning.

Oh btw observatory is steel frame (40mm x 40mm square "patio tubing").

Roger.