Amount of support needed for green roof

[alzum]

Hello all, great forum here, very handy.

I am currently in the design stage for a building at the back of my garden. Its my first large DIY project which I am doing to the best of my eco-minded ability.

I'm going to be building a studio for my drumming, so I don't annoy the neighbours anymore! The building will have a living roof which is going to be about 6m x 9m and will be a mono pitch.

My question is related to the support needed for the roof. I know its going to be heavy, so I am going to use 6 or 8 telegraph poles cemented into the ground as support. Beams going between these will then support the roof joists. The overhang of the roof will mean that the front to back of the building will be a span of about 4.5m which I need to cover with roof joists, so I will plan to space them about 400mm apart for strength.

What will be the best way to attach a beams to the telegraph poles, and what size of joist should I use for the 4.5m gap?
I'll add some sketches later when I can knock them up to have a think about the way I have in mind.

If you want to have a look at how the finished structure will look, go to http://inglepingle.co.uk/2011/11/take-precious-time/

Thanks for your time & help all.
Alun

 

[leew2]

As the building will be over 30m^2, I belive you will need structural engineer to specify the roof timbers to statisfy building control as it is a 'frame structure'.

 

[alzum]

Thanks for the quick reply. Technically, the building is not over 30m2 as the end of the roof is a large overhanging porch. The floor space of the building underneath (including wall depth) will take up less than 30m2.

Does building regs consider this, or will they consider the large overhang at the side of the building (6m x 4m) part of the floor space? Its not something that came up as an issue during an informal discussion with the planning office, though I'm waiting for them to send me more information after I sent them my plans. As it is, I don't need planning permission and building regulations weren't mentioned as a problem.