ADU costs

Seattle ADU Costs

Building an ADU structure in Seattle can be costly. People of Seattle will want to know how much their budget should be if they go for building an ADU/DADU on their property - we're here to help.

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Costs for building an ADU in Seattle


Nowadays, building a structure in Seattle is very costly. People of Seattle will want to know how much their budget should be if they go for it. But it is not possible to assume it correctly. Seattle ADU Builders will give you the ideas you need for this. You may want to build a small or large ADU and a garage with it. The more you want to add up, the more the cost. So, it is not possible to assume them exactly. But we can present you with an approximate idea about it. Besides the material, there is another added cost of the labor. In addition, every year, the price of building materials rises rapidly. 


Seattle ADU Cost


First, you should have enough confidence that you can afford the cost of the ADU once you start building it. Later, we will go for the estimate of an already built ADU to get an idea about the price. The builder is responsible for the total cost. If you want to make one in your basement, it will cost you more than 18K. The one in the above will cost you more than 360K because you will have to add extra costs to build the base. It is almost half of the cost of the ADU. 


If you want to participate in some of the jobs yourself, you can save some money. But if you're going to hand over the total project to the builder, they will hire laborers, and the cost will be more. The cost may be divided into some sections:


  • Design 
  • Utility 
  • Permit 
  • Construction 
  • Connection 


You will have to divide it in this way. Thus, making an estimate will be easy for you. You will be able to include there what types of design you want. The expense of available materials is costly and low-cost on the market. Even you need to include your furniture cost and gardening cost too. Let's prepare a list together about the Seattle ADU cost:


  • For the attached ADU minimum cost of 500 sq feet is $107,000, approximate 205 (per sq ft)
  • For the attached ADU maximum cost of 439 sq feet is $215,000, approximate 492 (per sq ft)
  • For the basement, the ADU minimum cost of 389 sq feet is $73,000, approximate 187 (per sq ft)
  • For the basement, ADU's maximum cost of 790 sq feet is $400,000, approximate 480 (per sq ft)
  • For the new DADU minimum cost of 390 sq feet is $110,000, approximate 275 (per sq ft)
  • For the new DADU maximum cost of 760 sq feet is $278,000, approximate 375 (per sq ft)
  • For the new DADU (above a garage) minimum cost of 790 sq feet is $125,000, approximate 155 (per sq ft)
  • For the new DADU (above a garage) maximum cost of 1640 sq foot is $450,000, approximate 270 (per sq ft)
  • For the garage conversion minimum cost of 570 sq feet is $70,000, approximate 135 (per sq ft)
  • For the garage conversion maximum cost of 380 sq feet is $160,000, approximate 410 (per sq ft)


We have added soft costs here. You may ask, what is soft cost again? Soft costs are the fixed fees you have to pay for designing, taking permits, engineering, etc.


The total construction costs are also here, called the hard cost. Through the cost per square ft, you will be able to come near the actual expenses. But it may vary according to other things. Some setups will be expensive for a standard ADU, like kitchen or washrooms. You may want to spend less on the lobbies.


Besides, you can reduce the cabinet's cost. Thus, there comes a balance in the total cost. But for the DADU Seattle's cost is not the same. For them, almost all the setup is costly. You should not waste any space around an interior of 750 sq ft or more. For example, you can't waste it in lobbies because the spaces are always very costly for DADU. There is no way to find an option for balancing the cost.


Earlier, we prepared a list of referring specific measures. But you may want to know about the cost of a bedroom, bathroom, and kitchen. The result of researching the cost of a backyard cottage for the last few years:


DADU (890 sq ft) with two bedrooms, two baths, and one sleeping loft costs:


Soft cost: $45,000

Hard cost: $310,000


DADU (800 sq ft) with 1 bedroom, 1 bath costs:


Soft cost: $42,000

Hard cost: $410,000 


Two stories DADU with one-bedroom, two baths’ costs:


Soft cost: $38,000

Hard cost: $360,000


As we already said, construction is very costly in Seattle. But, DADU has so many benefits, and you can use it in many ways. Think about it properly.


Now comes the idea of development costs. We want you to have a concept about it too. For the rising costs of everything, development costs are high too nowadays. The cost has been higher within the last three years, from $180K to $200K. So, as you see, they are raising $20K every year.


The costs are indeed increasing gradually. Still, you can quickly build up an ADU with a balanced price. You have to be extra careful about that.


A new ADU construction above your ground will not cost you more than $90K. You may lower the cost to $80K at most but not less than that amount. Consulting with the backyard cottage builders Seattle, we have reached this decision so far.


For building an ADU, you cannot ignore some fixed costs like foundation, concrete formwork, etc. They will generally cost you $12-17K. You will have to keep that in your mind too. The maximum size of an ADU of 1,000 sq ft is the allowed size in Seattle. So, the people are building one in a larger size than 700 sq ft. They have taken this opportunity to build up a large ADU.


But the key point is that the costs of an ADU may be different types. The cost of DADUs is in it too. The landlords need to have some creative mechanisms to arrange for the money to reduce the cost burden. Thus, they will be able to build up one at a low cost.


Emerald ADU Builders will always be your guide in this case. We will assist you in building one ADU at the minimum cost. To lower the cost of your ADU, we, one of the best Seattle ADU builders, will guide you through the techniques we have followed for years. Our years of experience are with you to be your ally and let you be relaxed!


Call (206) 222-2898 for immediate assistance.

How ADU Construction Process Works

  • 1. Send a request

    First things first - send a request to us to start the process. 

  • 2. Site Walk-through

    We will do a walk-through of your property to scope out the project and look for any issues. 

  • 3. Design & Planning

    Choose a building design and plan to the specifications of your property. 

  • 4. Permitting

    Permits in the city of Seattle are mandatory and we help you along with the process. 

  • 5. Build

    Once everything is approved we will start the building process.

  • 6. Completion

    After the build, we always do quality control and inspection for project completion.

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