This is the extension to my indoor layout I mentioned. Currently it is a meager 7ft6 by 5ft (average), soon to be 7ft6 x 9ft6 which should give me over 30ft continuous run. It means having some removable track sections to let me into the shed, although I can duck under easily as it is above waist height, and occasionally into the rear section of the shed where all the normal shed junk is stored. Civils are done, waiting on permanent way team to come along and lay some track once budget is approved, then the electricians can move in. Some pictures below.
Existing layout (left hand half) about 4ft wide at this end
Rear extension tunnelling through rolling stock storage shelves:
Run over desk and workbench, which is permanently in place; you can see the holes for the dowels used for attaching the side piece.
Run in front of door with some initial track in place:
I use 68mm x 20mm redwood for the joists and 6mm MDF topped with 3mm cork tiles for the track bed.