The SOTCW game at Gauntlet in 2009 needed an Italian Navy coastal watch station in a house overlooking the sea between Maiori and Vietri. At the time we managed quite happily with a model provided by Will McNally, which was just as well because I've only just finished the model I was meant to provide!
The model is built of foamcore and plastic card on a hardboard base. The brickwork on the end wall above is from one of those bases that come with the old Matchbox (now Revell) tank kits.
The windows, door etc are from a Wills pack of building accessories - very handy for this kind of job.
As usual with my buildings the proportions are determined by ensuring that the building fits neatly into a storage box I had available. In this case, a Clarks shoebox (child sized).