Cost To Build A Duplex

Building a duplex can be a great way to add value to your property. It can also be a great way to get a mortgage, as many lenders prefer this type of home over other options. However, it is important that you know what you are getting into before making the decision to build a duplex.

A duplex is essentially two homes built on the same lot. The two units are usually separated by a wall or fence and they share things like utilities. You will want to make sure that these utilities are paid for by both sides of the duplex, so that there are no issues later on down the road when one side stops paying their portion of things like water and electricity bills.

Additionally, it is important that there is enough space between the two homes so that you don’t run into any zoning issues with your local municipality or county government officials who oversee zoning laws for certain areas where you live in Canada or United States (depending on which country you live in).

What Is A Duplex Home?

A duplex home is defined as a type of residential property that attaches two living units to one another, and places two separate residences under a single roof. Duplexes can be single- or multistory structures, but the two individual dwellings that are contained within these properties (which essentially pack two units into one home) will have separate entrances.

Most commonly utilized as a form of passive real estate investment, duplexes effectively combine two units into one home, both of which may share an interior wall, floor, or ceiling. But both housing units are effectively separate residences with separate doors, interiors, and utility meters.

As opposed to single-family homes, duplexes allow for scenarios in which dual occupancy can be offered, allowing landlords to charge two rents, thereby increasing the earning potential of the property.

Duplexes are popular investment properties for homeowners who want rental income without owning a large multi-dwelling property. Duplexes come in many shapes and sizes, although they have many common attributes. The variations in size, style, material, and location lead to a wide range of building costs.

The national average cost to build a duplex is between $285,000 and $537,000, with most people paying around $388,000 for a 3,000 sq.ft. side-by-side duplex with two floors. At the lowest cost, you can build a 1,500 sq.ft. stacked duplex for $142,500. A 5,000 sq.ft. high-end single-story side-by-side duplex costs $1,100,000 to complete.

How Much Does It Cost to Build a Standard Duplex

The cost to build a standard duplex is typically between $300,000 and $500,000. This price includes the cost of building two homes on an empty lot and does not include the land itself.


Labor is usually the most expensive part of building a duplex, and it can vary widely depending on location. You can reduce labor costs by doing some of the work yourself or hiring experienced contractors who may be able to do more with less workers. For example, you could hire someone to dig the foundation for your new duplex instead of hiring an excavator. Or, if there are plumbing issues with one unit in particular, consider having the water turned off there before attempting any repairs so that you don’t have to pay for two plumbers at once (or at all).


The cost to build a duplex is the sum of all the costs related to building the property.

It includes but is not limited to:

  • Utilities – Water, gas and electricity, sewer and drainage, telephone, internet
  • Cable or satellite TV (if applicable)
  • Gas fireplace (if applicable)


Foundation costs will vary depending on the size of the duplex. Smaller duplexes can be built on a concrete slab foundation, while larger duplexes may require a concrete or wood foundation. Foundation costs are usually included in the overall cost of building a duplex, and typically range from $5-$15 per square foot.


  • Roofing Materials

The roof of your duplex is most likely going to be asphalt shingles. The type, color, and style of roofing material you choose will depend on the aesthetic preference of the homeowner and local construction codes. Asphalt shingles are a great choice for anyone looking for a low-maintenance roof that can withstand years of wear and tear without needing any repairs. They come in many different colors and styles—you just need to pick what suits your tastes best.

  • Roof Pitch

Roof pitch refers to how steep or shallow a roof is when viewed from above. A steeper pitch means there are more angles between each layer, which increases drainage capacity but also makes it harder for rainwater to run off the surface into gutters or downspouts (because there’s less surface area).

Interior and Exterior Materials

  • Exterior Materials
  • Plywood (2×4 stud) – $15 per sheet
  • Roofing material – $10 per square foot
  • Insulation – $4 per linear foot for fiberglass batts, or $1-$2 for foam board insulation.
  • Exterior sheathing – $7 per square foot for plywood and tarpaper, or $3-$5 for vinyl siding.



  • Lawn care. This can be done by hiring a lawn care company or doing it yourself. If you hire a company, this will cost an average of $10 per hour for one worker, plus any additional equipment needed to complete the job. If you do it yourself with just lawnmowers and other standard tools, this should not cost more than $50 per week in gas and supplies (for example: weed killer).
  • Planting trees/shrubs/flowers: You will need to consult a landscaper for advice on what types of plants would be best suited for your area. Once they have given you their recommendations, they can help guide you through the process of purchasing them and planting them in your yard or garden area(s). Depending on how big an area needs to be planted, this could cost anywhere between $300-$1,000 depending on what type of plants are chosen as well as how many people work together during installation time frames around noon when temperatures aren’t too hot out yet but still warm enough that watering isn’t necessary until evening hours when temperatures begin dropping down again past sundown – depending on where exactly your home is located within its surrounding community boundaries.
  • Mulching around trees/shrubs/flower beds: You can either buy mulch from stores such as Lowe’s or Home Depot which come pre-packaged with wood chips mixed into plastic bags ($4-$7 per bag) OR try making homemade compost by mixing together leaves collected off lawns throughout neighborhood areas where homes exist near each other (I’m talking about yards within blocks here rather than miles apart) then spread over ground after digging holes beneath desired tree trunks where roots extend downward toward soil beneath ground surface level – do not add fertilizer while doing so since overwatering could cause plant death due misapplication rate being too high when compared against actual needs based upon climate conditions affecting growth cycles throughout spring summer autumn winter seasons during year cycle periods.

Permits and insurance

Permits and insurance are other costs to consider. For example, if you’re building a duplex, you will need two sets of plans and permits: one for each side. You can get these from your local building department or architect who will also handle the necessary inspections.

If you’re planning on getting financing, lenders typically require that you have permission from your local government before issuing loans for home construction projects. In addition to this permit process, most banks also require homeowners to get liability insurance for their property during construction so that if someone gets hurt on site or damages another person’s property during the construction phase (for example, digging into an existing gas line), they won’t be held liable financially by any third party whose claims exceed what they’re insured against

Building a duplex can be a great way to save on housing costs.

A duplex is an excellent way to save on housing costs, especially if you live in a city where the cost of living is high. You can also use the income generated by one side of the duplex to help pay your mortgage or even invest in other properties.

There are many reasons why building a duplex may be right for you. For starters, they’re great investments that increase property value over time and provide additional rental income when needed.

In conclusion,

Now that you’ve seen how much it costs to build a duplex, you should feel confident in your ability to budget accordingly. We recommend starting with the foundation, roof, and landscaping costs as these will be the largest expenses. If you want to save money on materials, consider using reclaimed wood or recycled concrete instead of buying new lumber. This will help keep costs down while encouraging sustainability at the same time.

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