Adding on is the cheaper option. Building up generally costs more, because it usually requires more materials and labor. However, there may be some cases where adding on is not possible or is not the best solution, so it's always important to consult with a professional before making any decisions.

Between the option of building up or adding on, adding on is the cheaper option. When you build up, you need to hire a contractor and buy all the necessary tools and materials. This can be expensive, especially if you don't have any of the tools or materials required. When you add on, all you need is some lumber, nails, and a hammer. You can probably get all of this for under $50. So if you're looking for a cheap way to increase your home's value, adding on is definitely the way to go.