Which Is Better: Building a Ground-Level Addition or Second Story?

A house addition, the dream of many space-strapped homeowners, can either be built outward or upward.  Which is the better choice?

Answer

Building a ground-level addition outward is a better choice than adding a second story to your home.

Because

• Greater Privacy During Construction:  Do you like having work crews milling around your house?  If so, you’ll love building that addition upward, because crews will constantly be in your home.  In fact, you’ll need to vacate your house for periods.  On the other hand, building outward gives you back your house.  The most dramatic moment when you lose your privacy is when the crew breaks through, or opens up the wall between the addition and your existing house.
• Cheaper:  Hanley Wood’s annual Cost vs. Value Report says that, for a mid-range project, building an addition ranges from $43,232 for a one-room, 48 sq. ft. bathroom addition to $176,108 for a four-room, 768 sq. ft. two story addition.  Second story additions are far less common, so cost estimates are more difficult to come by.  Legal Eagle Contractors of Bellaire, TX estimates that second story push-ups should cost between $150,000 and $200,000 for a full upper addition on a 2,000 sq. ft. house and between $90,000 and $120,000 for a partial addition (500 to 700 sq. ft.).
• Less Invasive Construction:  With the “up” option, extensive post-construction work will need to be done on your lower level (drywall work, painting, etc.).  With the “out” option, only a little work will need to be done around the pass-through.
• No Additional Structural Support:  Can your present home physically support a second story?  If not, you’ll need to shore up your structure, thus driving up costs.
• Aging-Friendly:  There is a growing trend in building and remodeling called aging-in-place.  This movement emphasizes the value of homeowners remaining in their homes–often with significant modifications–rather than going to an assisting living facility.  An outward, ground-level addition is far more mobility-friendly than an upper story.

Qualifications

If any of these qualifiers apply to your situation, you may want to build that second story instead:

• You Want to Preserve Open Property Space:  When you put down a ground-level addition, you are not losing property.  This property is still yours, but it’s being inhabited by a wood-and-concrete squatter tenant who refuses to leave.  You’re losing less yard space, which you may want for other projects (pool, garden, arbors, sheds) or simply because you like having a wider band of privacy around you.
• It May Be Difficult to Merge Spaces:  Building outward, how will you transition from your existing floor to the new floor?  You can interweave wood flooring, but only if they both run in the same direction (end to end).  Building a second floor means you can install any kind of flooring without having to worry too much about matching materials.
• You Want Tighter Traffic Patterns:  Even though you’ve got that staircase to contend with, it’s still a shorter walk between all rooms of the house.   Building outward can seriously increase the distance from the two farther points in the house.
• You Are Concerned About Permit Issues:  When you build a ground-level addition, it pushes horizontally towards the property line.  Diminishing the buffer zone between your structure and property line means
• You Want to Avoid Foundation Work:  Ground equals foundation, and foundation equals big bucks spent digging. And heavy machinery in your backyard (or crews of men digging by hand). Then more digging. Foundation work drives up addition costs in a big hurry.