Obviously in some instances, despite what you might be told elsewhere, size does sometimes matter.  In response to a comment made on a previous post I thought I would provide some further information as requested.

To recap the overall scenic section of the layout is 8’ long by 3’ deep split into two 4’ x 3’ boards. These two boards bolt together face to face for transportation.
At each end of the layout are two fiddle boards, that due to using cassettes are simple flat topes with no track each being 6’ long. The one at the east (right hand) end of the layout is two levels to allow for the difference in heights between the shed track work and the main running lines at the rear.
All this has been designed from the outset so that they fit (i.e. total set up length including fiddle yards of 20’), along with the rest of the layout equipment and rolling stock into the back of a Ford Mondeo estate car.

With respect to the buildings on the layout:
The four road engine shed is approximately 650mm long by 300mm wide which allows for two tender engines to be held in each road.  A total of 8 Peco inspection pits are used within the shed.
The coal stage is approximately 260mm by 140 wide and the track level of the stage is approx 50mm above the shed rail height. The other main building is the imposing watertank and stores building, keep an eye out for a dedicated post about this structure. The main part of this building is 600mm long by 75mm wide.

I hope this gives a better idea of the size and context of the layout and some of the structures.