There are a few things to consider, including cost, individual needs, and what will add value down the road. Also important: your emotional attachment to the existing home.
As designer and builder Philip S. Wenz, the author of Adding to a House: Planning, Design & Construction, notes, an addition is much cheaper than building a new home and can offer a "new" home without the heartache of moving.
Can you finance the home improvement with your own cash or will you need a loan?
How much equity is in the property? A fair amount will make it that much easier to get a loan for home improvements.
Is it feasible to expand the current space for an addition?
What is permissible under local zoning and building laws? Despite your deep yearning for a new sunroom or garage, you will need to know if your town or city will allow such improvements.
Are there affordable properties for sale that would satisfy your changing housing needs?
Explore your options. Make sure your decision is one you can live with – either under the same roof or under a different one.