Raised Timber Frame Garden Room Roof Structure Information, help and advice on many architecture, self build and design problems and issues

[Mancave]

I am self-building a raised timber frame garden room and looking for advise on how to design a flat roof structure. Been struggling with it for weeks now.

The problem it is not a rectungular frame but a hex kindof shape like in the sketchup image below. The reason for the odd shape is due to my garden being 'odd shape' and I wanted to fit this timber room in that shape. Dim. are 6m x 4m plus a triangle at the back 6m x2.55m x5.6m.

The front needs to be under 3.0m high and the back 2.5m for premitted development. Also, will be looking to insulate (thermal and sound insulation)..but that's later.

I want a flat roof which is level inside and tappered on top (for rain water). But can't work out a structure to support a downwards slanting roof. I have bought 6" x 2" timber - 4.8m in length and planning to use them..somehow...Appreciate any advise, ideas..

[stoneyboy]

Hi mancave,
You have little option but to install the 6x2s parallel to the side marked 4.0m and to add firring pieces onto top of the joists. You will be able to adjust the position of the firring pieces to give you a level top to the roof but may have to put a facia on the lower end to disguise the height difference.
Regards S