Hi Mike - your buildings (and, indeed, your whole line) are something to envy - I really need to get on with things. Trouble is, getting the blue styrofoam is virtually impossible, lightweight blocks are as rare as the proverbial rocking horse ****, so its either wood, plastic or comcrete. Now concrete out here has a certain ubiquity - 99.9999999% of all structures are concrete! "A better house is concrete built" is the slogan - don't you believe it!
My line is not screwed down apart from on the trestles so is free to expand or contract.
When I get time I'll post Phase 2 (doubling the line) and then Phase 3.