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Cost To Build An Addition

Most homeowners spend between $24,897 to $42,357 nationally.
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Sometimes, in fact, more often than not, we all need more space. Whether it’s extra storage, another bathroom or a separate guest house for your family, an addition always comes in handy. Nevertheless, the cost to build an addition varies greatly depending on the room or floor you’re adding. See the full cost breakdown below. 

After, if you’ve decided an addition is right for you, ImproveNet can connect you with addition contractors near you!

National Build an Addition Costs

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Median Cost


Minimum Cost


Maximum Cost
Average Range:


National Average Cost $38,553
Minimum Cost $55
Maximum Cost $100,000
Average Range $24,897 to $42,357
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How do we get this data? This info is based on 3216 cost profiles, as reported by ImproveNet members.

Table of Contents

  1. Addition Prices & Types
  2. Home Addition Cost Factors
  3. Hidden Addition Costs
  4. How To Lower Addition Costs
  5. Addition Financing
  6. How To Determine If A Home Addition Is Right For Your Next Home
  7. Find A Pro

Addition Prices & Types

The average house addition cost is approximately $38,000, but we have seen prices as low as $3,000 for a single room or as high as $42,000 for an entire floor or guest house. Of course, that range is largely affected by the room type and how many rooms you’re adding. Below are some of the most popular home additions and their accompanying costs:

Single Room Addition 

The most popular type of addition is a single room. This includes a single bedroom, family room, living room, bathroom, or even extra kitchen. Despite sounding simple, even adding a small family room is no easy task. As such, there are certain costs you will incur no matter what type of room you’re adding: 

In addition to all the above, if you’re adding a bathroom or kitchen, extra plumbing costs will come up as well.

The final cost detail that will largely fluctuate based on the room you’re adding is whether to build out or build up. Building up is generally more expensive than building out as you have to make sure your foundation can hold the extra weight. However, for both projects, you’ll have to get permits and make sure you’re not breaking any zoning laws.

Additions Prices & Types

Sunroom Or Patio Enclosure

If you’re looking for more interior space and want to limit your costs, a sunroom or patio enclosure is quite popular. While the average cost to add a patio enclosure/sunroom is $14,180, we have seen prices as low as $500 or as high as $38,000. The final price will largely come down to size, windows, permits, décor, and sunroom choice.

To lower costs even further, you can buy prefabricated sunrooms for around $11,000. This price does not include heating and electricity costs, but if you only want to use the room during the day and warmer months, you can skip these costs altogether.

Detached Addition

The final type of addition is one that is detached from your current home. Typically, these include an extra garage, shed, or even a full guest house. While the average cost to build a shed is only $2,800, building brand new garages can go as high as $23,000. As you might expect, most homeowners hiring professional contractors to build brand new garages or guesthouses (average $25,000). Sheds or other smaller additions are oftentimes taken on as DIY projects, resulting in much lower addition costs.

Home Addition Cost Factors

As you briefly saw above, there are many factors that play a role in your final home addition cost. Sadly, many of them are volatile and are not the same from room to room or city to city.


Finding the right contractor is one of the most important things you can do as a homeowner in order to ensure the best possible result. If you’re adding a kitchen or bathroom to your home, your choice of a plumber can be critical to your project. An addition drives up plumbing costs dramatically since there is rarely any type of existing plumbing to use. Adding plumbing is a very labor-intensive job that must be done by a professional. Specific building codes must be adhered to, and a fully licensed and reputable plumber can provide ease of mind. You can lower your budget with the use of the cheaper ABS piping instead of PVC. Check with your plumber to see if this is a viable option because it can cut costs dramatically.


In addition to plumbing costs for a kitchen or bathroom, there are also costs associated with an electrician. Regardless of the addition type, you are likely going to need electricity. Often, a new breaker must be run from the main panel in addition to the various boxes needed to deliver power to fans, outlets, and light fixtures. Just as in the case of plumbing, electrical work is subject to a very high level of scrutiny by building and fire inspectors. Hiring a professional electrician will ensure quality and up-to-code work for your safety.

Home Addition Cost Factors

General Contractor

Your project will probably have a general contractor that does the bulk of the labor. They will be in charge of planning the addition, putting up walls and laying floors as well as any finishing work. Although some materials are necessary, the use of lighter, aluminum studs instead of traditional wood is not only cost-effective but less labor-intensive. Floating floors, which include tile and wood laminate, can now be installed for much less than any other option and deliver a brilliant final result.


If your addition is a garage, expect to not only pay a contractor and electrician, but also an experienced mason. A concrete slab must be poured completely level and with extreme expertise to prevent future pitting and cracking. In addition, an epoxy or polyurethane coat will be needed to properly seal the floor and protect it from tarnishing, staining, and flaking. A mason may be required if your foundation needs to be extended for the addition job.


When budgeting either a bathroom, kitchen, or garage addition to your home, it is imperative to get professional quotes for the cost of labor and to research where you can save money on materials wherever possible. Your home is a property investment, and to build an addition can add significant value when properly planned, budgeted, and executed by experienced professionals.

Hidden Addition Costs

To be honest, there are hidden costs and surprises that come with almost any home remodeling project. After all, you don’t know what is behind those walls, under those floors, or whether or not the previous contractor’s work is up to code until you get down and dirty.

Nevertheless, there are a few common costs many homeowners neglect because they are simply not common (or mentioned above). Don’t let them surprise you by reading the following home addition hidden costs:

Remodeling Contract

Contracts are long and boring. That is why many homeowners just sign them without reading just to get the project started. As you might imagine, this can lead to many unforeseen expenses.

Therefore, before you sign your addition contract, make sure it’s a fixed-cost contract. This type of contract protects you from unforeseen circumstances such as dry rot or mold in the home or large increases in material costs. Essentially, a fixed-cost (or fixed-price) contract guarantees you pay what is on the contract and if any other costs come up, they fall on the pro.

Hidden Addition Costs

Permit Costs

Almost every home addition will require a building permit. Permit costs are generally based on the estimated construction cost of the project. Depending on the project, electrical or plumbing permits might be required as well. On top of that, an application fee may be necessary. Permit fees can often exceed hundreds of dollars.

Finance Charges

If you’ve ever received a loan before, you know interest payments are part of the game. For larger additions, many homeowners get a remodeling loan to help with the large upfront costs. However, in addition to the interest payments, you’ll likely have to pay for an appraisal, an inspection, and processing fees. For more on addition financing, please see Addition Financing.

Home Insurance & Property Taxes

Sadly, more land comes with greater property taxes and insurance payments. It’s a fact of life. The bigger your house, whether through an addition or the original structure, the more you will pay in insurance and taxes (assuming all else is equal). As such, once the addition is complete, don’t expect the added costs to stop anytime soon.


Finally, if you build out, you will have to pay to fix up your landscaping. Whether it’s excavation repair or simply adding mulch, certain landscaping costs will pop up and should be considered before any home addition.

How To Lower Addition Costs

How To Lower Addition Costs

With any home remodeling project, no matter the size, there are always little shortcuts you can do to lower your total cost. Whether it’s helping out with the work, getting a loan from a friend, or choosing another renovation route, you have plenty of options when it comes to decreasing that house addition price.

  • Refinish your basement or attic as both are cheaper than building an addition
  • Add storage with cabinetry or by clearing out clutter
  • Add a detached addition as opposed to an attached addition
  • Get down to work with your contractor
  • Get a loan with no interest from a friend or family member
  • Go buy the materials yourself
  • Apply for the permits yourself

Addition Financing

As you have read, most additions are not cheap. Luckily, there are many types of loans banks and lending institutions offer when it comes to home additions. The following three types are the most common. 

Once you’ve read over the basics below, be sure to talk to your lender as they can most likely find the best option for your specific addition.

Home Equity Loan (HEL)

A home equity loan is just like a mortgage. You borrow a lump sum that is secured against your home, and the payments are amortized over several years. Usually, the interest rate and monthly payment remain fixed throughout the term of the loan. This option usually carries a higher interest rate than refinancing your mortgage.

Cash-Out Refinancing

Cash-out refinancing involves refinancing your mortgage for more than you currently owe and pocketing the difference. For example, say you owe $50,000 on a $150,000 house and want $20,000 to add a family room. You could refinance your mortgage for $70,000, and the bank will then hand over a check for the difference of $20,000. 

Home Equity Line of Credit (HELOC) 

A home equity line of credit (HELOC) is a good choice if you’ll be paying for your project in stages. With this option, the lender agrees to advance you money up to a specified limit, and you access the money as needed with a debit card or checkbook, making it easy to pay contractors. Monthly payments can be lower than those of a home equity loan since you have the option of paying interest only on the money you withdraw. The other important difference is that HELOCs carry adjustable interest rates, while home equity loans typically have fixed rates. 

For more loan options, please see Renovation Financing.

Addition Financing

How To Determine If A Home Addition Is Right For Your Next Home

Home additions are not only intended for current homes, but for future homes as well. We all want bigger houses, but many homeowners should know that moving into a smaller home and putting in an addition could save you a ton of money. It all comes down to price, time, and a willingness to live through the renovation. After reviewing all three factors, you will know when it’s right to move into a bigger home and when it’s right to move into a smaller home and take on a renovation.


The most important factor in deciding whether to buy a big home or a smaller one and renovating is the price. As hard as it is, all homeowners must determine the price of the smaller home, accounting for all the addition costs (including moving out during construction if need be) and then comparing it to the cost of the bigger home.

How to Determine the Price of Smaller Home 

After talking with a contractor, you must add up all the costs of the renovation. Always remember to include the cost of materials, a contractor, loan interest, time off work, and hotel fees if you plan to move out during the process. Remember, there are always some hidden costs when it comes to home additions.

Then, after talking with a real estate professional, subtract that number from the likely market value after the renovation. If you don’t want to talk to a broker, you could also research comparable prices in the new neighborhood. In essence, the difference in value should not exceed the asking price.

Need to Determine Price Per Square Foot of Both Homes 

When comparing the prices of the two homes, you should also factor in the price per square foot for each home. In simple terms, the price per square foot for the smaller home, after the renovation, should be less than the price per square for the larger home. Remember, you must take into account all the renovation costs, including the aggravation of living through a remodel. Simple math, illustrated in the example below, should help clear your mind.

Let’s say your bigger home is 3,000 square feet and the asking price is $600,000. Therefore, the price per square foot is $200. A smaller home may be 2,000 square feet and the asking price is $400,000. In this case, you would have the same price per square foot before the renovations take place. After renovations, you have the 3,000 square foot home you always wanted. Assuming you put in $100,000, taking into account all those hidden costs discussed above, your new price per square foot would be $166.66. Less is always good, but homeowners must decide if that $34 per square foot (difference) is worth the hassle of living through a home remodeling project. 


Needless to say, all homeowners would love to move into their dream home all ready and good to go. However, certain financial limitations can sometimes alter your plans. As is the case with any remodeling project, time will play a key factor.

Some families need to move into a finished home. Whether big projects are coming up at work or you are just fed up with remodels, many homeowners refuse to think about home additions. Finances are most likely not an issue, so why not move into your dream home as soon as possible?

However, there are other families who may not mind living in a home during construction or have financial restraints. A great reason to buy a smaller home and put in a home addition later is to delay additional expenses. If you buy the larger home, you are putting all the money on the table right away (or each month with a mortgage). If you buy the smaller home, you are putting down less money and can choose when to spend the extra for the addition. This is a great option if you can’t afford an addition or bigger home right away.  

Patience is a virtue and that is just as evident in the home remodeling industry as it is in any.

How To Determine If A Home Addition Is Right For Your Next Home

Willingness to Live Through Renovation

As I noted above, some families refuse to go through a renovation. If that is the case, then buying the smaller home is out of the question. On the other hand, if you and your family are willing to get to work and live through the remodeling process, then buying the smaller home is well within your reach. 

We will be the first ones to admit that living inside the home during the renovation process can get dirty, cramped, and aggravating. Many homeowners decide to live with friends, family or in a hotel during this time. Remember, if you do decide to get a hotel, be sure to incorporate those costs into the new price per square foot. Needless to say, if you are able to tough it out inside the home, you can save a lot of money.

Another way to save is by doing some of the work yourself. It’s very simple. The less work you contract out, the less money you spend. Many families enjoy getting their hands dirty. Others like creating their dream homes. The possibilities can go on and on, but if you’re planning on buying the smaller home and renovating, we highly encourage you to get involved.

Find A Pro

There are many moving parts when it comes to home additions. Sadly, very few general contractors can handle all the work themselves. As you read above, quite often, architects, plumbers, electricians, roofers, and more are involved.

Fortunately, ImproveNet can connect you with the right addition contractor near you so you can get your project off on the right foot!

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