I think the Heffley family didn't plan everything of the construction and they also had to plan the details, like whether would they take neighbor's lawns, what were they going to do with the extension, which company should they use and so on, the same about moving, even though they held a family meeting to decide what to do with the extension.
It's impossible for a lighter person to fall off a ladder and be less hurt than a person who weighs more falling down from the same ladder. I am impressed by how Gregory did in physics.
Greg's dream house is sooooooooooooooooooooo expensive that I think even if you had all the gold on earth, you still could never build one.
One thing: do NOT follow Gregory.