My house had a looooong rectangular deck, laced with rotted wood that stuck out into the back yard like a boat dock at the lake. Access to the back yard was awkward thanks to this rickety protrusion into it. PLUS, my dog and I deserved enclosures from the cold winter breezes snapping at our south side. The third consideration was the single entrance to the basement half of my house which made it officially unfit for habitation as lacking an emergency exit.
I rebuilt the deck to a more useful size and shape, adding a doghouse basement with south-facing glass to give him a nice view of the world. Of course I also got a protected area with south-facing glass above the doghouse.
The other part of this project was to create a second entrance/exit to the 2 bedrooms, bath and living area in the basement. The photo below shows that portion of this project underway. I excavated along the foundation, cut a doorway, insulated outside the concrete and enclosed the ramp.
My 2-bedroom home sold as a 4-bedroom after a relatively inexpensive remodel.