Guards and Wards
is stupidly good. Seriously, this spell does it all. Fog? Arcane Locks? Unmappable terrain? Hidden doors? spooky magic mouths and dancing lights?
Even better: Dispel magic only hits ONE instance of the effects, so they can't just dispel it.
Alternatively, the house is a very large mimic. Omnomnom.
"The door is stuck. The windows are stuck. In fact, upon further examination the doors and windows now seem to be just a textured wall...also, it's leaking acid"