Take a likesided piece of cardboard. Mark where the middle of each side is and then the middle of each section. You will end up with 4x4 likesided small squares. As seen below.
Cut through the cardboard where the red lines are. Cut, but not the whole way through, where the spotted white lines are - this is to make it easier to fold.
Bend it carefully where the rooftop will be, and lay the two squares in the middle together. Tape them, and do the same on the other side.
Take the two other ends and fold them to the middle, try to keep straigth angles. Glue them together, hold them together for a while to make sure they are stuck. Make the same thing on the other end of your house.