What does it Cost to Build a Duplex in 2022

Maybe you're looking to build an investment property that you can rent out, or you want to build a new home for your family that has a ready income source built-in. In that case, a duplex house could be exactly what you're looking for. Coming in a range of shapes and sizes, with equally varying price points you have a lot of options when undertaking duplex construction.

If you're thinking of building a duplex in Chicago, Fortress Home are experts in the field, having built hundreds of residential buildings in the city over their 20+ years of operation.

Find out how much your duplex will cost to build with a free consultation. Call +773-770-8607 or email [email protected] When looking for the “Home builders near me”, choose experience, fair prices, verified reviews and extensive portfolio of successfully completed projects.

What exactly is a duplex house?

A duplex home is a type of real estate defined as two separate residences under a single roof and may also be categorized as a multifamily home. They will have their own entrances and utilities, so in that respect will be stand-alone dwellings, but they will share walls or floors/ceilings.

Duplexes suit various different situations which might include:

  • Investment rental property — with a duplex you get two rental units in one building which is great for cash flow as a landlord, as it's unlikely that both units will be empty at the same time. The cost to build a duplex will be lower than the cost of building two separate houses.
  • Extended families — a duplex home can be great for extended families who want to live close to each other but still have separate lives. They work well for grown-up children, elderly parents, or even visiting relatives.
  • Extra income — if you are planning to build a new house you can take the duplex route and live in half and rent out the other half, with regular rental income. This gives you an easily manageable rental unit, as well as a new home. In this case, it's important you choose your tenants carefully as you will be living close to each other.
  • Home conversion — if you have a particularly large house and only use part of it you can consider converting it into a duplex, to make money from all the unused space, without having a stranger living directly in your home. This can work well after children have grown up and left home.

Different types of duplex

Duplexes come in a variety of styles and can either be side-by-side or one-up, one-down. Side-by-side units have the option of being one- or two-story. Duplexes are also available in as wide a range of styles as traditional single-family homes, from ranch style to modern farmhouse and mid-century to Victorian.

There are advantages and disadvantages to each type of duplex.

One-up, one-down stacked

The main advantages of stacked duplexes are that you can potentially fit more residential units on a smaller plot of land. Of course, each unit will be smaller but that might be more suitable for the rental market in your area. If most units are rented by single tenants or couples a smaller stacked duplex unit might work well.

It's also easier to stack the utilities, minimizing the length of pipes and wiring required as you will probably put bathrooms and kitchens on top of each other.

On the downside, you are more likely to have noise issues with a shared floor/ceiling than with walls, especially if you have tiled or wooden floors upstairs. Another negative for some is that the front door of one of the units is likely to be upstairs.

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The right construction company will build your residential project in timely manner. Side-by-side duplex units feel less like apartments and more like individual residences, each with an entrance on the first floor. If they are two-story they will also have the potential to be larger than stacked duplexes.

Sound is also usually less of an issue, especially if you are careful about which rooms share the adjoining wall.

On the negative side, building side-by-side duplexes requires more land and foundation and roofing costs will also be higher. Two sets of pipes and wiring will need to be installed which can also bump up the costs.

Cost to build a Duplex

The average cost to build a duplex can vary greatly depending on the style, layout, and size of the building. According to HomeAdvisor, the construction costs range from $142,000 to $1,100,000, depending on many different factors.

National average cost by type

One of the factors affecting the duplex construction cost is location but looking at national average costs the price per square foot for a duplex range from $95 - $220.

How much does it cost to build a duplex by type (national average figures):

  • Stacked (one-up, one-down) — $115 per square foot
  • Side-by-side, one-story — $145 per square foot
  • Side-by-side, two-story — $175 per square foot

While we don't have exact figures for the cost to build a duplex in Illinois, based on single-family home costs (of which figures are more readily available) it is likely to be around 65-70% more expensive than the national average figures.

Please note all these figures include all the labor and materials costs but will not include the cost of land, which can add a substantial sum to the final bill, depending on where you are in the country.

Duplex costs by square footage

The size of a property will be a major factor when calculating the final costs and here are some average costs based on the square footage of the duplex you choose to build:

  • 1,000 square foot duplex — $157,500
  • 2,000 square foot duplex — $315,000
  • 3,000 square foot duplex — $472,500
  • 4,000 square foot duplex — $630,000
  • 15000 square foot duplex — $787,500

These prices assume mid-range materials and labor costs but don't include land or your architect and general contractor fees.

Materials costs

You can generally break the costs of a construction project down into two areas, labor and materials. Your materials costs are likely to include:

  • Cement for foundations
  • Wood for framing, roofing, and other carpentry
  • Flooring materials
  • Drywall and insulation
  • Window and door units
  • Siding and roofing materials
  • Wires and electrical fittings
  • Pipes and plumbing fixtures
  • HVAC ductwork and equipment
  • Paint and other decors
  • Home appliances and furnishing

Labor costs

Labor costs also make up a sizable chunk of the overall project cost, and many figures don't include your general contractor fees which can range from 10-25% of the total project cost. While this may seem expensive, hiring a reliable and respected general contractor, like Fortress Home in Chicago, can prove to be invaluable. They will manage the entire project for you making it all run smoothly and keeping delays to a minimum and costs down.

Labor costs will also include, and possibly others depending on the duplex building type:

  • Architects
  • Foundation experts
  • Carpenters
  • Roofers
  • Plumbers
  • Electricians
  • Painters

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Factors affecting the cost to build a duplex

Materials and level of finish

Like any type of real estate construction, an important cost component is the level of finish and materials chosen for the project. Choosing high-end, luxury materials will push your project towards the higher end of the duplex price range, whereas using basic standard materials and simple finishes and fittings you can keep your costs down and end up with a budget duplex project.


The location of your new build duplex has many cost components to it:

  • Land costs vary by state as well as a rural or urban location
  • Labor and materials costs can be partly location dependent
  • Weather conditions in some locations will add delays leading to additional costs

Time of year

You might not believe it but the time of year can also affect the final cost to build a duplex house. At peak construction times you might have to wait longer to get the specialist contractor you need and general labor and materials costs might surge due to high demand.

If you build in off-peak season you might be hit with costs due to weather delays (that's why it's off-peak).

Size of building

One of the biggest factors affecting the average cost of building a duplex is the size of the building. The larger the structure the more materials are required, and the longer it will take to build. However, as a real estate investor, this extra cost might be worthwhile as you will be able to make more money from your rental properties.

Frequently Asked Questions

Is it profitable to build a duplex?

Building a duplex can be a great real estate investment, giving you a regular passive income through rental income. However, it is important to do your research first and see if there is a market for units of the type you are planning to build, in your neighborhood.

If it is a neighborhood with lots of single-family homes and very few apartments it might not be an ideal location for a duplex unit. However, if there is a shortage of smaller affordable rental units in your area building a compact stacked duplex could be a great investment.

How much do you have to put down to build a duplex?

Generally, when you are building a duplex you will require a construction loan instead of a more traditional mortgage. Construction loans generally require approximately a 20-25% down payment. However, you should speak directly to your bank or lender to find out their specific requirements for construction loans.

The amount of down payment will also depend on whether you're planning to live in the duplex, with investment properties generally requiring larger down payments.

Is it cheaper to build a house or duplex?

Generally speaking, it is cheaper to build one single-family home than a duplex. However, duplex building costs will usually be cheaper than building two houses, so the cost per residential unit is lower. This is down to the factor that a duplex only requires one foundation and one roof and can often sit on a smaller plot of land than two separate houses. However, the final price to build a duplex will still depend on many factors like the location, choice of materials, and standard of finish chosen.

Your duplex building partner in Chicago

When you have decided to build an actual duplex, speak to Fortress Home in Chicago, experts in duplex multi-family home construction. With expert knowledge of the local zoning and building regulations and an understanding of what makes an appealing rental property in Chicago, we'll help you with your construction project every step of the way. Call or email us for a no-obligation consultation: +773-770-8607 or [email protected]

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