New Space Addition Cost

How much does it cost to add new space?

Adding on to any home, whether it is an expansion of the existing "footprint" or an entirely new level is a very complex project. For this discussion we will examine the requirements and general costs associated with adding a single-story 192 square foot (12'x16') room. This type of project will not be considered a "DIY" project in the least, and several contractors will be necessary for the job (carpentry, installation, electrical, etc.).

For the new addition such as described above, the typical costs include:

  • According to Hanley Wood and their "Remodeling" magazine the average basic addition in which a foundation is added, vinyl siding is applied, adequate roofing is done, interior walls are insulated and finished, new carpet and windows are installed and all electrical and HVAC works is completed will cost $23,804. The resale value of this update would hold at $19,757, or an 83% return on investment.
  • The above figures place the cost of the addition at $124 per square foot. This pricing structure assumes that carpenters charge an average of $70 per hour, electricians between $65 to $85 per hour, and painters between $20 and $35 per hour.

Cost breakout

What needs to be included:

  • Architectural design services to ensure that new addition is housed in a structure in a style appropriate to the existing house, and up to code for the neighborhood or area in which the home is located. This should require no more than 10 - 17% of the total building budget;
  • Arrange any required demolition, excavation, or site preparation - Average costs are going to vary according to the level of work necessary;
  • Pour concrete footings and slab if no crawlspace foundation exists - Average price of concrete is $75 per cubic yard, with piers and the full slab it that would require roughly 14 cubic yards and would cost at least $1050;
  • Build roof trusses and support beam system and tie into existing structure - lumber prices will vary as will the design used by the carpenters constructing the new space. The project should require 2x4 wood framing along with OSB structural sheathing;
  • Asphalt shingles with galvanized metal flashing - Average of $80 to $100 per square of 50-year shingles. Total cost of $450, plus installation time of at least 16 hours;
  • Install vinyl siding and trim - Average price of $7 per square foot installed, and for the 514 square feet needed, this would total $3600;
  • Finish ceilings and walls - Drywall throughout would require 20 panels of 4'x8' for walls and ceiling at $9.80 each (plus screws, nails and finishing compound) for an approximate total of $250 plus approximately 24 hours of installation;
  • Fiberglass wall and attic insulation with R-49 and R-28 values respectively value will cost an overall average of $2.00 per square foot (installed) for an approximate total cost of $825;
  • 1 - six-panel primed hardboard door - Average of $178 each plus four hours of installation;
  • Three new windows - Average price of $300-$700 per window, plus installation time of two to five hours per window. Be sure that the windows purchased will qualify for tax deductions;
  • Carpeting - Averages at $15 to $25 per square yard (with padding and installation) totals $533;
  • New moldings - Average of $3.00 per foot of installed molding for a total of roughly $850;
  • Tie into existing HVAC - Average cost will vary according to pre-existing system;
  • Provide electrical wiring and lighting to code - This is going to depend upon the amount of work required, but electricians average from $65 to $85 per hour. This project might be priced on a per item basis, or the electrician might simply base it on the square footage; and
  • Provide carpentry to code - This is going to depend upon the amount of work required, but carpenters average $70 per hour. This project might be priced on a per item basis, or the carpenter might simply base it on the square footage.

Enhancement and improvement costs

  • 6 recessed ceiling lights; and
  • Painting of trim and walls.