A 1x1 spacious apartment, a 2x2 fancy residence, or a 3x3 stately manor will expand when it evolves. When it could expand in multiple directions, which will it choose? The question isn't very important, since solid objects can be used to prevent the house from expanding in "wrong" directions. However, I sometimes try to play missions without deleting anything (other than objects that are present initially, such as the Kingdom Road). Besides, I was curious.

I performed quite a few experiments on expanding 1x1 houses, and enough experiments on expanding 2x2 and 3x3 houses to give me a fair amount of confidence in these results. But, of course, I could have missed something.

A house will only expand over bare ground, gardens, vacant lots, and lower-level housing. The preferences are:
a) entirely lower-level houses and/or vacant lots,
b) empty land, perhaps with some lower-level houses and/or vacant lots, but no gardens,
c) gardens, perhaps with other stuff.
For example, a house that could expand either south over empty land and lower-level houses or west over just lower-level houses, will expand west.

If a house could expand into equally attractive spaces in different directions, the preferences are:
1) south,
2) north,
3) west,
4) east.
For example, a house that could expand south over gardens and empty land, west over just empty land, or north over just empty land, will expand north.

The practical implications are left as an exercise for the reader.