I made a house here, gimme a day or two to finish since I have a lot going on lately.
There's rules for that as well:
Unfinished houses:
they stay for 24 hours, then we'll delete them if they don't look promosing.
They WILL be removed tho if we detect spam.
The builder can come back at any time within these 24 hours and continue, we'll notice that - and hopefully let your build stay.
Everything has to do with how many redspots there are avaliable at the moments as well.
Finished houses:
They stay if they look like houses.
They will be removed if we detect spam.
If they're very nice, we'll let the builder chose another spot, or a blue spot.