Cottages and longhouses

The Civilian Structure Costs table on ACKS 127 lists cottages and longhouses as both costing the same 300gp, but, based on the descriptions, it looks like the cottage is a more complex structure (two stories - it’s 20’ high and includes “wood stairs”) and has four times the floorspace (two 30x30 floors vs. a single 30x15 floor). Is this correct?