We decided to design and make our own "from scratch" design this year. First we looked through some books for inspiration, then starting sketching some ideas. When we decided the look and size we wanted, we started sketching it out on large sheets of tracing paper. All sides had to be planned out, including a top view. Then we measured and sketched each piece that we would need to bake, and made sure they would fit on our cookie sheets. The large wall in the back had to be split into two pieces, since it was too large.
We kept the originals, and made copies of the outlines, in case we wanted to use them again. The tracings we used get cut up, and ultimately thrown away. Every little piece has to be thought of at this time, so that you can make sure all the pieces are baked and ready to assemble at once.
With this house, we decided we wanted it higher, so we made a foundation of rice krispie treats. The only problem we had with that, was that they were too fresh. We should have baked them at least a day ahead, so they would harden a bit. As it was, the weight of the house squished the rice krispie treats a little.
We usually use a large piece of foam core or gatorboard for the base and cover it with a layer of foil. It needs to be large enough for a yard around the house, and strong enough to support the weight of the house. We made a batch of royal icing and colored it brown to match the gingerbread, since we had som cracks we were going to have to patch. The used different colored icing for the decorative part later. It takes at least two people to assemble a house, especially one this size. As one person holds two pieces in place, the other pipes the icing along all the sides, from the inside, to secure the parts. Once the main walls are in place, it's important to let it sit for at least a hour or so, so that the icing can harden. If you put the roof on too soon, it will collapse.