How Much Does it Cost to Build a Duplex?

There is a reason why infants are left to sleep alone in a separate room. And there is also a reason why 18-year-olds live out of their parent’s house, either by choice or by force.


But some people, either parents or the adult children, who are half-hearted about the idea of living apart from each other, might opt to live in a duplex house. This way, they can live separately from each other, but not far enough to call for help anytime.


Attached houses, including duplexes, have been on the top three most preferred type of house bought by the Americans in 2014 according to the report of the

This is understandable because of the cost of building a detached house is so expensive for middle-income earners and spending in the vicinity of a million dollars is out of the question.

Average Cost to Build a Duplex

The national average cost of building a duplex according to is $138,500 for a 900 square feet room, with mid-range materials, a normal foundation with full and finished basement, efficient doors and windows, and with finishing ready for occupation. This costs roughly around $154 per square foot although the national average stands at $85 to $125, which is typically on the lower end of the spectrum.


Therefore, a two-room duplex would cost $277,000, if we consider all factors directly proportional to the overall project cost.

In addition, a two-storey, four-unit duplex construction of wood and stonework would average around $552,000 to build. This is composed of $273,000 worth of materials, $268,700 labor cost, equipment cost of $9,800, and contractor supervision worth $79,100.

The labor costs average $70 per hour for carpenters, masons, and excavators; electricians charge $65 to $85 per hour; plumbers’ rate range between $45 to $65 per hour; and painters charge $20 to $35 per hour.

residential duplex house

What are Included

The duplex building costs would include the basic design of the duplex which is a simple, rectangular shape consisting of the simple four-square units. And since, the construction of duplex cannot be a DIY work, hiring an architect and a contractor is a must. These two professionals take the 10% to $17 of the total budget for the project.


The architect’s role is the determination of the scope of the project and the estimates of the preliminary budget; preparation of the draft and final proposed work and outline of plans that include schematic design and floor plans; serve as project manager who administers the construction, complete construction documents, and work with structural engineers and meet with planning agencies to ensure that the project complies with building regulatory requirements.

On the other hand, the contractor’s role is to provide the materials, labor, equipment, and other services that may be required by the project. If it cannot do some of the details, may hire a subcontractor depending on the need; completion of all the permits required for the project; and deliver the final cleanup of the entire project.


In short, the total duplex building costs are consisting of the construction costs or the amount you would spend to build the duplex, site work cost or the cost to prepare the site which includes access for the people, transportation and equipment to and from the worksite; the design and consultants’ fees; and all of the permit fees to be allowed to construct according to or in compliance with regulations.

Additional Costs

Before any construction can be made, you must first acquire a lot where you would want to build the duplex. Prices vary per location.

The estimated cost is limited to the actual duplex only and if you want to include site improvements like if you want to include a parking or a garage, a garden, or a play area for the kids, then prepare to set aside an additional budget for them.


Shopping for Duplex House

If you want to find out how much is the cost to build a duplex house in your area, offers a locator of contractors who in turn give free estimates based on where you want to build the duplex.

Factors Affecting Duplex Building Costs

Especially so when working on a budget, you must consider all factors before deciding to construct a duplex complex. They could be more depending on circumstances but some of these factors may include the following:

  • The type of materials – your choice of materials, whether low-cost, mid-range, or high-cost would greatly affect the overall cost of the project.
  • The size of the duplex – the rest of the cost components of the project is directly proportional to the size of the duplex being constructed


  • How many rooms – the number of rooms on the project would mean additional materials and therefore expect a higher cost of building a duplex
  • The style of the construction – depending on your preference or the contractor’s suggestion, the duplex, and its parts can be built from scratch or the standard masonry and carpentry materials; or through the use of pre-fabricated parts like the doors, windows, and the kitchen, among others. The use of the latter is more convenient if you work on a timeline and cheaper but it can sometimes compromise the quality and the overall style of the house.
  • Location – all the prices of materials  and labor is usually dependent on the location as manifested in the cost of the real estate in a particular state, city, or county


  • Contractor – the people in charge of the completion of the project get a significant chunk of cost
  • Professional Fees – the architect or the engineer hired by the contractor or by you being the owner also dictate how much the contractor would charge the homeowner.
  • Pre-existing structure – the existence of a structure prior to the construction of a new one would greatly affect the overall cost of the project. Either you save some when you just continue or renovate the pre-existing structure, or you spend additional cost on demolishing or removing it from the site.
  • Housing market – how well the real estate business is doing also affect the overall pricing of a residential project. The status of the housing market can be assessed by how fast a project can be disposed of, like when a pre-selling of a development project is selling like hotcakes, expect that the location has a booming housing market.


A renowned home improvement expert with almost 20 years of experience in building and repairing beautiful homes in the USA. He's a civil engineer by profession.

2 thoughts on “How Much Does it Cost to Build a Duplex?”

  1. If possible could you give an estimate of how much a one level duplex ranch style home would cost. With walkout basements and without. Square footage of both 2,250 each individual unit, side-by-side. Owner will occupy one unit and rent out the other. Both units will have their own double car garage.

  2. Please give an estimate of how much a one level duplex ranch style home would cost. No Basement. Square footage of 1,250 each individual unit, side-by-side. Open floorplan with 2 Bedrooms/2Baths per unit. Two sisters will occupy the units. One sister in each duplex. Both units will have their own one car garage. We are looking at property in Crawfordville, FL.


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