Allow the gingerbread to cool 5 to 10 minutes after removing it from the oven.
Cut one rectangle width-wise into three even parts. Use one of the parts to measure a similar cut from the second rectangle, so that there are four parts the same shape and size. Two parts are for the sides of the house, and two for the roof.
From the rest of the second rectangle will be the gables. Measure the height of the side pieces against what is left of the second rectangle and make a mark to know where to start the point of the gable. Measure the widths of the roof pieces from that mark to know how tall to make a point of the gable. Once one gable is cut out, it can be used to measure the second.
Choose a flat dish or pan on which to build the house. Layer enough icing on the pan to help the house stand. Stand aside piece adjacent to a gable and fill the corner between them with icing, on the inside and out. Stand the other side and gable to complete the rectangle and fill the rest of the corners with icing.
Spread icing on the top of the sides and gables and allow it to harden a little before placing the roof pieces. Once the roof pieces are placed on top, spread icing on the seam between them. The icing in the cracks and corners should keep the house together while decorating.
Decorate with what is left of the icing, candy, sprinkles, chocolate, and goodies to taste. The extra gingerbread shapes can also be used to decorate the house.