How to Add a Second Floor to an Existing House

Updated April 17, 2017

Adding a second story to your home is a viable option if you need to expand your home on a small property. It's a major undertaking, however, and requires extensive planning and financing. Even if you secure the money and a permit to build, your existing house and its foundation might not be able to support the added weight of a second story. The reward, however, of a second story is the added space and improved aesthetics in your home.

Determine if it's legally feasible. Visit your local building permits office to learn whether a second story is permissible in your residential zone. Write down any height restrictions or other regulations concerning second stories.

Consult with remodelling constructors to get a rough estimate of how much per square foot you can expect to pay for the second story. Include the cost of a full bath in the estimate. Add a 20 per cent contingency cost to that figure.

Find out if you qualify for a bank loan based on your remodelling cost estimate. Decide whether that's a debt you feel comfortable assuming.

Assess whether the existing structure can handle the added stress of another story. Judge not just the exterior walls, but the foundation and the earth it rests upon. Usually a concrete slab poured directly onto the earth can support the extra structure. A house built upon a full basement, concrete beams or drilled piers usually cannot handle the load and will sink into the ground over time.

Draft architectural plans showing how the existing plumbing will connect to an upstairs bathroom, whether the existing electrical panel will support the extra load, where a staircase would be erected and how sound will be dampened between floors. Make plans for heating and cooling, too. Building along the lines of existing pipes cuts back expenses.

Remove the roof of your existing home, lay down the second-story floor and erect the walls.

Build a staircase connecting the two floors. Top off the second story with another roof.


Talk with other homeowners who added a second story and how they survived the construction process. Ask them for any tips and what they would have done differently. Factor the added expense of finding another to place to live during construction into the remodelling costs. Save the shingles from your existing roof to place onto the new roof.

Things You'll Need

  • Permit
  • Bank loan
  • Architectural plans
  • Building supplies
  • Contractor
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About the Author

Kyle Martin has been a newspaper reporter in Florida for over three years, and was a reporter in Mississippi before that. He is fluent in Spanish, having lived overseas during his formative years. He has a Bachelor of Arts in communications, with a concentration in journalism from Mississippi College.