[Astrodude]

Hi All,

Just after some input on a shed conversion. I recently moved into a house which has very limited horizons - but there is a big shed out back which I am planning to convert part of into an observatory.

A section of the roof will be converted into roll on - roll off set up, and a platform will be installed isolated from the mount.

My questions at this point relate to the pier's design and construction. The pier is going to need to be about 2.7 metres above ground level. (Access to the ground beneath the shed is not a problem - it is a chipboard/bearer/stump construction). At the moment I'm planning on creating a concrete pillar (using formatube) 300mm (12 in) in diameter reinforced with bar. The foundation for the pillar will be a poured reinforced concrete block about 600mm x 600mm about 1000mm deep.

Do these specs sound suitable?
Can i get away with making a concrete block that is less deep?

Also, I'm a bit confused about the order of construction - does the formatube get set into the foundation block and then filled later, or does the block alone get poured first, allowed to set and then the formatube set on top over the protruding reinforcement bar and filled?

Thanks for any advice. Cheers.