How To Calculate Home Addition Costs

Sep 14, 2020 | General Contracting, Remodeling

How To Calculate Home Addition Costs

If you have insufficient space, but you aren’t ready to sell out your property, home addition is your ideal solution. It would be best to consider the cost involved to avoid getting caught in a money-pit project that drains your savings. Here is a detailed guide to get you started.

How Much Does A Home Addition Cost?

Home addition refers to the construction of a new structure within the same residential space. Most people opt for this to give their home a makeover while others need to meet their families’ changing needs. Each additional project has a different cost based on size. The following factors determine how to calculate home addition costs.

Cost Per Square Foot

Using this criterion, you can pay anything between $50 and $250 or above. It’s worth noting that more complex projects cost more and simpler ones less. Most contractors base their estimates on your project’s size, types of frames needed, and the foundation work required. A 20×20 area can cost you from $80 to $200 per square foot. Besides, they consider whether your project will require extensive plumbing and wiring.

The cost per square foot also covers labor and the value of the material. Note that the labor costs may vary depending on the cost of living in your residential area, and the entire projects become more expensive in high-end regions.

To establish a reasonable estimate, consider calculating how much space you intend to add in square meters. For instance, if you wish to extend your backyard at 14 feet from one end and 20 feet across, multiply it to obtain 280 square meters. You then times the figure with the cost per square foot, which varies from one region to another.

There are many ways in which you can increase the square footage on your premises. You can choose to add an extra floor or a section that attaches to an outward opening or wall. In addition to the factors mentioned above, let’s dive deeper into other elements that may drive up your home addition costs.
Building Material Costs

Any addition will require different materials depending on the style and availability. In Florida, most people use concrete blocks while in Georgia, they prefer concrete with wood framing. Also, when making a garage, you may have to spend a substantial amount of concrete pour. Due to the difference in materials, the price can range from $10 to $20 per square meter. Remember that different materials also require various skills, which further impacts on cost.

Labor Cost

It’s worth noting that each significant addition needs multiple skill sets. Some projects need architectural drawings to guide the contractor on the building plans. Some will charge you a certain percentage of the entire construction work or on an hourly rate. You can pay about $875 to $2 500 but will differ based on your project’s scope.

Complex additions require intricate work, but DIY tasks will save you more money. With the right skills, you can maximize the productivity and cost-effectiveness of your construction project. You may also need to include other experts, like painters, electricians, carpenter, drywall installers, and siding contractors. Additionally, you will pay for building permits, which goes for $100 to $300 each. Further, you need to run a soil test that can cost you $1,000 and above.

Cost By Type Of Room

Some projects will require plumbing, closets, cabinets, and flooring, making your home addition cost either less or more expensive. For instance, while constructing a new kitchen or bathroom, you need to add a new plumbing system, which drives the prices even higher. One great tip to save on this is to connect it to the existing plumbing system if the project allows. Below are average prices that you can pay for various space additions.


About all homes comes with a kitchen, so most additional projects involve expansion or remodeling. You will have to pay different prices for plumbing and cabinetry. The average kitchen addition cost can range from $48,000 to $95,000. However, this may vary depending on the type of flooring, appliances, framings, and finishes you intend to use.


If you often host guests and have insufficient rooms for them, adding an extra bedroom will improve their privacy and comfort. It costs slightly lower depending on your needs, but closets and storages will slightly increase the cost. For a smaller 12×12 room, you can pay between $11,520 and $28,000, but for a bigger space can cost you from $21,000 to $63,000.

Living Room

Often, the living room may consume high-end materials, including hardwood, marble floors, and other great features. On average, it may cost you up to $54,000.

Additions in a bathroom cost much higher since it requires extensive labor to install the features, tiles, and shelving. Additionally, the bathroom fixtures are somewhat expensive. Overall, bathroom additions may cost between $400 and $450 per square foot. If you have a more massive extension with some luxurious additions, you can pay $700 to $850 per square meter.

Laundry Room

A standard laundry room covers about 35 square meters but may need some waterproof materials, storage spaces, and other appliances. On average, you can pay up to $7000 for this type of addition.


It’s merely a roof extension with a window that adds more space in low ceiling rooms. The project can cost you about $5,000.


A garage extension, including a simple detached space with no plumbing or electricity, can cost you roughly $9,000 to $12,000. On the other hand, if you wish to include additional amenities, be ready to pay from$18,000 to $35000.

In-law Suite

As the number of people living in multilingual households continually rises, people are now opting for a detached suite. It contains a kitchenette, bedroom, living space, and bathroom. It costs higher, and you can spend from $78,000 to $135,000 on average.

Second floor

An extra floor costs significantly higher than adding a room on the ground level. It involves the removal of roofs and the addition of new floorings, spaces, and other fixtures. It may cost around $300 to $500 per square meter. If you have a larger home, you can spend from $150,000 to $200,000.


The cost of creating a basement depends on how big it is and how high the contractors will raise your house. Expect to pay at last $50,000, but it may be higher depending on your area’s soil type and house size.

Factors To Consider When Setting Up Additions At Your Home

When constructing an addition in your property, it would be wise to consider its appearance once attached to the main house. You wouldn’t want to have an extension that seems hastily stuck on your home. Instead, you should notice a natural flow from the addition to the old space.

Hence, ensure that you reach out to the right professionals and choose materials that compliment your original home. Although the extensions improve your home’s value, it may be a turn off to your prospective buyers if it appears out of place. Here are various considerations to help you make an informative decision.

Purpose Of The Addition

If you want to add office space, a bedroom, or bathroom, it would be best to do it on the second floor. On the other hand, while looking forward to expanding the entertainment room or kitchen, the ground floor is a more convenient option.

The basement works as a cost-effective option while adding extra spaces like guest rooms or playrooms. You will undertake inexpensive remodeling and finishing that can cost you from $12,000 up to $20,000.

Your Property Value

The extension should improve your house’s value by increasing functionality and convenience. In most cases, ground floor additions work best since they suite a large group of people, including the elderly, if you wish to sell your property in the future. Still, you may want to consult your local realtors to know which addition works best for your region.

Space Available

Some homes have minimal spaces, and building a ground floor extension requires you to sacrifice valuable backyard area. While in such a situation, it would be wise to consider second-floor additions.

Convenience During The Construction Period

While doing an extra floor, you need to get prepared for constant disruptions. Additionally, you may have you move out of the house during construction. Therefore plan and pick an extension that best suits your family.
Related Questions

Do The Additions Add Value To Your Home?

Improvements in your master suite, bathrooms, and sunrooms may result in an approximate increased resale rate of 63%, 53%, and 49%, respectively. Besides, adding an extra floor with a master suite and downstairs living area may boost the value of up to 65%.

How Do I Arrive At The Estimated Cost?

You can use an online home addition calculator that uses algorithms and mathematical equations powered by technology. Professional contractors also use science, facts, and experience to give you an estimate. Still, you have to account for the labor and materials cost, which may affect the value.

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