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?


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


  • 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.


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.

Cost of Sunroom?

Sunrooms exist in that kind of hazy Twilight Zone of addition-building.  Is it really an addition?  Does it qualify as a real structure?  And how much do sunrooms cost anyway?

The problem is that you cannot get a fix on the price of a sunroom without having a nasty salesperson call on you and give you the hard sell.  That doesn’t sound very good, does it?

If you want a “short answer,” I’ll give you a $10,000 to $15,000 cost estimate for an average sunroom.  For a more nuanced answer, read on…

Cost of “Average” Sunroom

First, it depends on the type of sunroom you want.  DoItYourself.com has what I think is a pretty good fix on Your Basic Ordinary Sunroom, which they define as having:

  • A standard knee-wall
  • Half glassed
  • Solid roof sunroom
  • 400 square feet

Estimate:  about $10,000.  I am inclined to go higher than that:  $15,000.

Cost of Owens-Corning Sunroom:  Ouch!

But what about a fancy, complete package sunroom?  The Owens Corning SunSuites® Sunroom is one such no-hold-barred sunroom, with a fiberglass frame, integrated electrical system, roof, and a generous amount of glass.

Thanks to a promotional contest run by Owens Corning, we can fix the cost of this sunroom at about $40,000.

Owens Corning SunSuites Sunroom