Thanks, all. But remember, the credit for the design goes to Old Norse church-builders. I just adapted the design on request.
I've been playing a small household in this house, and it seems to work well. However, I have not yet hired a butler or maid or bought a Bonehilda coffin, and I understand there are sometimes pathing issues when staircases are stacked (as I do here, placing the 2nd to 3rd storey stairs directly atop the 1st to 2nd storey stairs), so that may be an issue to watch out for.
One other shortcoming is the ground floor powder-room (half-bath) behind the stairs, between the kitchen and dining room. Because Sims will pick the closest available sink when cleaning dishes, if they eat in the dining room, they'll be tempted to do the washing up in the bathroom. When they eat in the kitchen, they seem happy to use that sink (or, in my case, the dishwasher, because I decided they could have one
).
