garage foundatiosn and roofing

[changed]

hi everyone...

i would like to ask for a bit of advice please..

i am about to start building a single brick garage in my garden. I say garage, but it will actually be used for storage rather than parking, as access to it is limited. I have obtained planning, but i am limited to a maximum height of 2060mm high above ground level to fit in with existing features on the site. I know its not great, but it is all i can have, i may dig down a bit and lower the surrounding ground level in the area to help ease this if i can, but even then i cant get much back.

Two questions...

Firstly foundations. There are many close walls to the site so digging down too deep is not really what i want to do. The soil is clay/chalk borders. I was hoping that a 600mm trench would suffice, or a 300mm floating slab?

Secondly the roof, obviously it will be flat and as thin as possible! i was thinking 150x50 joists with a plywood cover, and a sheet covering on top. Hopefully this will be less than 200mm thick leaving me 1860mm headroom inside (lucky i'm short ). But does anyone have any other ideas? every extra inch counts..

 

[Static]

Photos speak a thousand words..
Also how big is your garage gonna be, 45m x 45m to house your collection of 80 odd 1972 VW camper vans?

 

[changed]

single garage... 3.2mwide x 5.4m long, maximum external height 2060mm.

No photos, but basically i have a site which is approximately 3600x 6000mm walled on 3 sides with existing brick walls 2060mm high. The planning approval dictates many things about how it looks but more importantly that the new structure does not exceed the height of the wall.

 

[Static]

150x50 (or 145x47) C16 timbers at 400mm centres can do 3.1m clear span so you should be fine with them so long as you span the joists the short direction. Make sure you screw the ply down as well..
BUT.. youll need to create a fall say 1:40 on the roof so your firings are gonna be about 80mm high on one side (again assuming fall to the short 3.2m direction)..

Might want to consider lowering the area by a couple of hundred mill