How not to build a house

I went to build a house

So I started with the roof.

Tiles or thatch, I wondered,

Which is more fireproof?

Soon the roof was finished,

So I started on the walls.

I fitted all the windows,

Added two nice halls.

Next I build the floor,

‘Twas the smartest house in town,

Except for one small detail:

It was upside down.