What size structure you need will largely depend on what you’re using the structure for. As an example, if you only need a deck for a small dining table, you might only need it to be 12 by 12. However, if you want your deck to have a full-fledged outdoor kitchen and plenty of seating, you may need a deck that’s significantly larger than this. For fences, you’ll need to take your values and lifestyle into account. If you want a fence primarily for privacy reasons, you may need a taller fence.