How Much Does A Home Addition Cost In Seattle?

A home addition built by Wise Choice

Are you considering a home addition in Seattle? Are you wondering how much exactly does a home addition cost in Seattle? It depends on many factors, including size and scope, materials, labor, permits, and more. In this blog post, we’ll break down the typical costs associated with building a home addition in Seattle so you can make an informed decision about your project.

What Is The Cost Of A Home Addition In Seattle?

Home additions are a great way to add living space and increase the value of your home, but they come at a cost, especially if you are adding a second story to a house. Let’s break down the average cost and typical range for home additions in Seattle.

Average Cost

Per Manta, the average cost of a home addition in Seattle, Washington, is almost $68,000. This is slightly higher than the nationwide average home addition cost of $50,000, according to Angi.

Typical Cost Range

The typical cost range for home additions in Seattle starts at $14,500 and goes to almost $121,000, according to Manta.

However, before we dive into the factors that can affect the cost of a home addition in Seattle, we should note a few caveats regarding the average cost and typical range figures cited above.

First, the size, the scope of the project, and the material quality can drastically change the home addition cost. In other words, the type of home addition you want will be a major factor in your final cost.

Second, it should be noted that the average cost of a home addition figure cited above is naturally weighted towards lower-cost projects since those are the types of home addition projects most commonly done. So if you are looking to build a major home addition with high-end materials, you can expect to pay a significantly higher price.

Last but not least, the quality of work is not addressed in the average home addition cost. To put it another way, you get what you pay for when it comes to labor and the quality of work.

Here at Wise Choice Construction, we are committed to delivering the highest-quality workmanship, as well as clear communication with the customer throughout the process. That is why we offer a 5-year craftsmanship warranty on all work that we produce. You can learn more about our process and home addition pricing tiers here.

Factors That Affect The Cost Of A Home Addition In Seattle

A staircase leading to a rooftop home addition built by Wise Choice

There are several factors that influence the ultimate cost of a home addition. Here we will explore some of the most influential ones–so keep reading to discover more!

Size And Scope

The larger the project is in terms of square footage or complexity, the higher the cost will be. On the other hand, smaller projects are less expensive since they require fewer materials and labor hours. However, it’s not just a matter of square footage but also the purpose and design of the home addition. For example, constructing a basic extra bedroom would be a lot more cost-effective than constructing an exquisite master suite with a walk-in closet and private bathroom.


As noted above, another major factor in the cost of a home addition is the contractor you hire to do the work. If you hire a reputable contractor such as Wise Choice, Construction, you will likely pay more than you would for a “Chuck in a truck,” but you will also get quality workmanship and a smooth and transparent experience throughout the construction process. If you DIY your home addition project or hire an inexperienced contractor, you will likely pay less at the outset, but you may end up with subpar workmanship or worse.


If you need plans drawn up by an architect for your project before the building can begin, then this will add to your overall costs. According to Angi, an architect typically charges 5% to 20% of the total project cost.


The type of materials used in your home addition will also affect its overall cost. Certain types of stone or wood may be more expensive than others, while some types of finishes may require additional labor time to install correctly.


Where your house is located can have an impact on costs due to regional differences in labor rates and supply and demand for various materials and services. Generally speaking, if you live in an urban area where land is at a premium, building an addition is going to be more expensive than if you live in a rural area.


Labor costs can vary significantly depending on who you hire and what type of expertise they bring to the job site. Another factor is the amount of specialized labor your project requires. For example, electrical and plumbing work are both highly-skilled trades that will typically cost you more than just painting work.


When beginning any construction project, permits must be obtained from local authorities, as well as any necessary inspections conducted during various stages of construction. Depending on where you live, there may be additional fees associated with obtaining these permits, as well as additional inspections required for local building codes once the project is complete. In general, the cost of permits can range from several hundred to several thousand dollars, depending on the size, scope, and complexity of your project.

Site Prep

Site preparation, such as grading or excavation work, may need to be done prior to beginning actual construction. This can add additional costs depending on the scope of work needed for your particular site conditions. Generally speaking, the cost of site prep usually ranges from $1,500 to $10,000,


Once construction is complete, cleanup costs should also be taken into consideration when estimating total expenses for your home addition project in Seattle. Disposing of debris properly is essential not only for safety reasons but also because many city ordinances mandate that waste can only be disposed of at approved sites within a certain radius from where it was generated. This could mean additional travel time and disposal charges which should all be factored into total expected costs prior to beginning any demolition or renovation work related to a home addition project in Seattle.

Home Addition Cost By Type

Over garage home addition

Let’s explore the different types of home additions and their associated costs in Seattle.

Living Room Or Family Room

The cost of adding on a basic living room or family room can range from $17,300-$43,200 on average, per Angi. This usually includes adding walls and ceilings as well as window installation. It may also include electrical work, insulation, and drywall setup. Of course, if you want something more luxurious, like built-in entertainment centers or custom cabinets, then you can expect to pay a premium for those add-ons as well.


If you’re planning on renovating your home by adding a bedroom, anticipate spending at least $8,600-$21,600. This covers basic construction expenses like walls, ceilings, and windows. However, if you want a primary bedroom suite fitted with more luxurious additions such as closets or bathrooms, then the total costs might surpass $100K.


Kitchen additions are one of the most expensive home projects because they require plumbing and electrical work in addition to carpentry and other construction elements. Kitchen additions typically cost between $48,000-$95,000, depending on the complexity of the project.


Sunrooms are great for taking advantage of natural light while enjoying outdoor views from within your home. This type of addition usually costs between $16,135-$70,000, depending on whether you opt for traditional sunroom construction or more advanced solarium-style designs with large glass panels for increased sunlight exposure.

Laundry Room

A laundry room is a great option if you’re looking for more storage or just want a dedicated space for doing laundry. The cost of adding a laundry room to your home varies greatly depending on size and amenities but typically ranges from $2,000 to $15,000 per Home Advisor.

Home Theater

Adding an area dedicated to watching movies is one way many homeowners choose to upgrade their living spaces these days. The cost of this type of addition may vary significantly depending on how sophisticated your design is but generally falls somewhere between $20,000-$70,000 due to factors such as soundproofing requirements, state-of-the-art audio/video systems, and special seating arrangements, according to Bob Vila.


Adding an extra bathroom is useful if your family has grown larger or if you frequently have guests over who need access to shower facilities when visiting your home. This type of addition usually costs between ,200 to ,500 for a basic bathroom design. However, if you select premium materials or if your bathroom addition requires significant plumbing or electrical work, you can easily spend more than $100,000.

Second Story

If you’re looking to add a partial second story, be prepared to pay between $80,000 and $250,000. However, if you wish to construct a full-fledged second-story addition to your home, then plan on investing anywhere from $100,00 -$600,000.


Building a detached garage will cost about $25,000-$50,000, depending on the size and materials used. For an attached garage, the cost typically ranges from $15,000-$25,000. If you want to upgrade the interior of your garage with insulation or drywall, that will add to the total cost.

Front Porch

The cost of a front porch will vary depending on the complexity of its design, typically ranging from $4,600 to $22,200 per Angi.

In-Law Suite

If you opt for a basic in-law suite, like an additional bedroom, it might cost anywhere between $8,600 and $21,600. However, if you want something more luxurious–such as a detached unit–then plan to set aside up to $100k or even higher.


A bump-out is an extension that protrudes from the side of your house and adds additional space for features like closets or bathrooms. These can range from as little as $1,700 for small projects up to more than $18,900 for larger projects, according to Home Advisor.


Mudrooms are functional entrance rooms where people can hang up their coats and take off their shoes. Mudrooms can range in cost from $8,000 to $16,000, according to Home Advisor.


Balconies typically cost anywhere from $5,000 to $10,000, according to Home Advisor.

Modular Addition

Modular additions are prefabricated structures that are delivered straight to your property ready for installation and typically range between $20,000-$30,000, according to Home Advisor. Their total cost usually depends on how large they are and what kind of features they include (like plumbing and electrical).


A cantilever addition is one where part of the structure hangs off the side of your home without any supports underneath it, giving it an elegant floating look. This involves installing sturdy joists or beams on the exterior of your home in order to extend beyond the existing foundation of the first floor. On average, this will cost you between $15,000-$25,000, according to Bob Vila, depending on its complexity and features selected.

Home Addition Benefits

Construction of the second floor inside home.

Keep reading to learn more about the benefits of building a home addition in Seattle.

Increased Property Value

One of the main benefits of building a home addition is that it increases your property value due to the fact that it adds square footage to your home. This means that installing an extra bedroom or bathroom can add significant resale value and make your home much more attractive to potential buyers down the line. The amount of value that a home addition adds will depend on the type of home addition you installed, as well as the specific housing market in which your home is located.

Additional Living Space

Another benefit of building a home addition is that it provides additional living space for you and your family. A home addition can be anything from an extra bedroom or bathroom to an office or den where you can work from home or just relax after a long day. It’s also a great way to create additional entertaining space where you can host friends and family for dinner parties or game nights.

More Storage Space

Adding an extra room gives you the opportunity to install built-in shelving or cabinets for all of your books, DVDs, records, etc., as well as store seasonal items such as holiday decorations and winter clothing when they’re not in use. With additional storage space comes increased organization and tidiness–a must for any busy household!

Alternative To Moving

Rather than uprooting and relocating elsewhere when you need more room in your house, adding on provides the perfect solution without having to leave familiar surroundings behind. This can be especially important if you have children who prefer to stay in their current school or if you want to maintain your current work commute. It’s also much less costly than buying another property outright.

How To Save On The Cost Of A Home Addition

Whether you’re looking to add an extra bedroom or expand your kitchen, home additions are great ways to increase your home value and create more comfortable space for you and your family. While these projects come with considerable costs, there are also plenty of ways to save on home addition costs.

Here are a few cost-saving strategies you can use when taking on a home addition project.

  • Take advantage of your home’s existing infrastructure–if possible, use rooflines, doorways, and windows that already exist for your home addition in order to reduce building costs
  • While we recommend leaving complex work to the pros, you can save money by DIYing smaller tasks, such as painting a room or handling landscaping around your home addition
  • Look for ways to reuse existing components like flooring or wall studs instead of purchasing new building materials
  • If possible, look into alternative materials instead of what is typically used–this can include anything from choosing engineered lumber over natural wood or refinishing items rather than going with new pieces
  • If you are getting eco-friendly features such as solar panels, you may qualify for a tax credit from the government
  • Remember to set aside an extra 10-20% for contingencies in your home addition budget
  • Make sure that all plans are thoroughly considered before starting construction which will help cut unnecessary costs throughout the process

How To Pay For The Cost Of A Home Addition

Person calculating home addition cost

Adding space to your home is a great investment, but one that comes with a price tag attached. Luckily, there are plenty of ways to finance home additions without breaking the bank. Here are a few common options.

Home Equity Line Of Credit (HELOC)

Another option is taking out a home equity line of credit (HELOC). A HELOC uses the equity in your home as collateral and offers lower interest rates than most personal loans because it’s secured by your house. However, this option does come with certain risks; if you fail to make payments on time or stop making payments altogether, your lender could foreclose on your property. Additionally, HELOCs often require closing costs and annual fees—so make sure you read all the fine print before signing any paperwork.

Financing Via The Contractor

Another way to finance your new home addition is through financing provided by the contractor who will be doing the work. Some contractors offer financing plans that allow homeowners to spread out their payments over time with low-interest rates and no closing costs or additional fees. This can be especially helpful if you don’t qualify for traditional financing due to poor credit or limited income—but keep in mind that not all contractors offer this type of financing, so it’s important to ask before signing any contracts.

Personal Loan

Another option is to take out a personal loan from your bank or credit union. A personal loan is an unsecured loan that is typically offered at a fixed rate and term. You can usually get approved with good credit and receive the funds quickly—often within days of submitting your application. The downside is that personal loans tend to have higher interest rates than other financing options, so make sure you shop around for the best deal before signing on the dotted line.

Credit Cards

Credit cards often come with high-interest rates and can be difficult to manage if not used responsibly–but they do offer some benefits such as rewards points, cashback bonuses, and 0% introductory APR periods, which can help offset some of those costs if used wisely. Just remember that most credit cards also have annual fees, so make sure you understand all associated costs before using this method of payment.

Seattle Home Addition Cost: DIY Vs Hiring A Pro

DIY Costs: If you choose to take the DIY route when adding to your home, there are some initial costs that you will have to consider before starting the project. First and foremost is the cost of supplies and materials. This includes everything from lumber to paint, as well as nails and screws. You will also need building tools, which can add up quickly if you don’t already have them on hand. Finally, there’s also the cost of labor, which for a DIY project, is basically the value of your time.

Hiring a Professional Contractor: While this option is more expensive than doing it yourself, it does come with certain advantages. For one thing, hiring someone else means that you don’t have to worry about making mistakes and having to go back and fix them later. Instead, the work will be done right the first time around–especially if you hire a reputable contractor with lots of experience, such as Wise Choice Construction.

Having someone else handle the job also gives you peace of mind knowing that they’ll take care of all the necessary paperwork, such as permits and inspections. Generally speaking, professionally installed home additions hold their value better over time due to superior construction skills. So decide what is more important: cost savings now or greater cost savings over time.

Questions To Ask When Planning A Home Addition in Seattle

Wise Choice employee takes measurements

What’s The Purpose Of The Addition?

Will the new space be used as an extra bedroom? A playroom for kids or grandkids? A library or office? Whatever the purpose of your home addition in Seattle might be, it’s important to know how you plan to use the space before moving forward with any decisions. This will help shape the design of your home addition and give you an idea of how much square footage you need.

What is the Budget?

The most important question to consider when planning any type of renovation project is how much money you’re willing to spend. It’s important to have an accurate budget for the entire project, as this will help ensure that everything stays on track. Be sure to factor in any unforeseen costs that may arise during the construction process, such as additional materials or labor costs.

What Type of Permits Do I Need?

Before beginning any kind of construction project, it’s essential that all necessary permits are acquired beforehand. This includes building permits as well as any city permits that may be required depending on where you live in Seattle. Your contractor should be able to assist with acquiring these permits, so make sure they are familiar with local laws and regulations before moving forward with construction.

Wise Choice Construction Can Bring Your Dream Home Addition To Life!

Home additions are an excellent way to increase property value and add living space without having to move locations. Before embarking upon one, however, it’s important that you understand how much it may cost so that you can plan accordingly. By learning about all the factors that go into determining the final price tag associated with adding onto a house–including the scope of work needed, materials used, and labor required–you’ll be better prepared to make an informed decision about whether or not this type of project is right for you.

If you are ready to move forward with your home addition project in Seattle, we would love to help! Our team at Wise Choice Construction can help you plan and execute your home addition so that it fits both your needs and budget. Just fill out our contact form today, and we’ll help you get started.

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a small house with blue doors and a porch.