If we are going to build a basement, do we need both an architect and an engineer?

No, if you’re building a basement you really only need a structural engineer to design it because they are the ones who take into account what will be sitting on top of its slab and walls. When it comes to having the entire home drawn up, you could substitute the architect for a home designer if you need to save money. If your budget can handle the cost and you need the entire home drawn up, consider using both to make sure your home is built exactly the way you had it drawn up. Designers don’t always get it right when it comes to beams and corners being exactly where they are supposed to be.