New garage - roof size known, how to size slab?

[theflyingpig]

I'm thinking that in order to minimize material waste my new garage roof will be exactly 6m wide. That way the deck and insulation will use whole sheets..
Taking into account the cladding needs 50mm, I need to know how wide to pour the slab....

That make sence?

 

[noseall]

I'm thinking that in order to minimize material waste my new garage roof will be exactly 6m wide. That way the deck and insulation will use whole sheets..
Taking into account the cladding needs 50mm, I need to know how wide to pour the slab....

That make sence?

Slab?
You mean set out the strip foundations, surely?

 

[theflyingpig]

Slab?
You mean set out the strip foundations, surely?

No, we're laying a reinforced concrete slab and building off the top of that.