How Much Will it Cost to Build Your Home Addition?
Understanding cost and budgeting factors for your addition
Custom Home Addition
The cost of your home addition depends on what you want to achieve with it. More complicated home addition projects that involve a lot of complex changes to the existing home tend to be cost more. Most home additions fall into one of three types of projects. Read their descriptions to see which one best fits your expectations for your addition.
Select One
Simple Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$150,000 – $200,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$200,000 – $300,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$300,000 – $650,000
Exterior (Construction)
Interior (Completed)
As the lowest cost option, a simple addition will also have the most limited scope. An addition in this category would involve adding only living space to the home, such as a bedroom, office, or family room. Essentially, it’s an addition with four walls and a roof that is easy to design and construct.
Simple additions can be thought of as “best-case scenario” projects with no major challenges or issues. The land lot must be level and require minimal excavation. To avoid excessive engineering and design costs, the shape of the addition must be rectangular and follow standard structural principles.
A single-level bedroom addition built on the side of the home with a crawl space foundation is a good example of this type of project.
Common features of a Simple Addition include:
- Single level on the ground floor
- Slab or crawl space foundation
- Bedroom, living room, or office
- No major excavation
- Minimal plumbing & electrical
- Basic structural design
Standard Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$200,000 – $300,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$300,000 – $650,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$650,000 – $1,200,000
Exterior (Construction)
Interior (Completed)
These types of addition projects are still relatively simple in scope but may involve a few features and challenges that make it more difficult to design or construct. A standard addition may add extra living space or utility space, such as a bathroom, kitchen, or laundry room.
Standard additions often require more engineering and involve a more complicated construction process. For example, a kitchen addition, which adds square footage to the home in the form of a new kitchen, must go through an extensive design process to design the cabinetry layout and appliance arrangement. Challenges that require extra steps in the design and construction processes add to the cost of the project.
Additions with custom bathrooms or kitchens would fall into the category of standard additions.
- Basic shape with some variation
- Slab or crawl space foundation
- Bathroom, kitchen, or laundry room
- Requires some excavation
- Lighting fixtures
- New flooring
Complex Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$250,000 – $400,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$400,000 – $800,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$800,000 – $1,500,000+
Exterior (Construction)
Interior (Completed)
In the case that your addition requires extensive engineering or specialized construction throughout the design, that would qualify as a complex addition. This category of additions is reserved for projects that are exceptionally complicated in scope and design features.
An addition may fall into this category for several reasons. It may be because the planned addition drastically changes the structure of the existing home. Or maybe it’s because the addition is exceptionally large or complicated, requiring new plumbing, electrical, and HVAC systems throughout. It may also be that the project falls into a niche architectural or interior design style that involves specialized construction work to complete.
Additions on historic homes, multi-level additions, and additions that function as accessory dwelling units (ADUs) may fit into this category.
- 2nd story, basement, or multi-level
- Complex, custom shape
- Multiple rooms & functions
- New flooring
- Updated backsplash
- New lighting fixtures
- Custom features
Simple AdditionSimple Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$150,000 – $200,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$200,000 – $300,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$300,000 – $650,000
Exterior (Construction)
Interior (Completed)
As the lowest cost option, a simple addition will also have the most limited scope. An addition in this category would involve adding only living space to the home, such as a bedroom, office, or family room. Essentially, it’s an addition with four walls and a roof that is easy to design and construct.
Simple additions can be thought of as “best-case scenario” projects with no major challenges or issues. The land lot must be level and require minimal excavation. To avoid excessive engineering and design costs, the shape of the addition must be rectangular and follow standard structural principles.
A single-level bedroom addition built on the side of the home with a crawl space foundation is a good example of this type of project.
Common features of a Simple Addition include:
- Single level on the ground floor
- Slab or crawl space foundation
- Bedroom, living room, or office
- No major excavation
- Minimal plumbing & electrical
- Basic structural design
Standard AdditionStandard Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$200,000 – $300,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$300,000 – $650,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$650,000 – $1,200,000
Exterior (Construction)
Interior (Completed)
These types of addition projects are still relatively simple in scope but may involve a few features and challenges that make it more difficult to design or construct. A standard addition may add extra living space or utility space, such as a bathroom, kitchen, or laundry room.
Standard additions often require more engineering and involve a more complicated construction process. For example, a kitchen addition, which adds square footage to the home in the form of a new kitchen, must go through an extensive design process to design the cabinetry layout and appliance arrangement. Challenges that require extra steps in the design and construction processes add to the cost of the project.
Additions with custom bathrooms or kitchens would fall into the category of standard additions.
- Basic shape with some variation
- Slab or crawl space foundation
- Bathroom, kitchen, or laundry room
- Requires some excavation
- Lighting fixtures
- New flooring
Complex AdditionComplex Addition
SMALL ADDITION
— 100 – 300 SQ FT —
$250,000 – $400,000
MEDIUM ADDITION
— 300 – 600 SQ FT —
$400,000 – $800,000
LARGE ADDITION
— 600 – 1,000+ SQ FT —
$800,000 – $1,500,000+
Exterior (Construction)
Interior (Completed)
In the case that your addition requires extensive engineering or specialized construction throughout the design, that would qualify as a complex addition. This category of additions is reserved for projects that are exceptionally complicated in scope and design features.
An addition may fall into this category for several reasons. It may be because the planned addition drastically changes the structure of the existing home. Or maybe it’s because the addition is exceptionally large or complicated, requiring new plumbing, electrical, and HVAC systems throughout. It may also be that the project falls into a niche architectural or interior design style that involves specialized construction work to complete.
Additions on historic homes, multi-level additions, and additions that function as accessory dwelling units (ADUs) may fit into this category.
- 2nd story, basement, or multi-level
- Complex, custom shape
- Multiple rooms & functions
- New flooring
- Updated backsplash
- New lighting fixtures
- Custom features
What Affects the Cost of Your Home Addition?
There are several factors that may influence the cost of your home addition. Here are the 3 most important ones to consider when planning your project.
1. Level of Customization
The more customized your home addition designs, the more the project will cost. Custom work requires more labor and higher-quality products, so be prepared to pay more for custom features.
2. Labor & Construction Administration
Some homeowners prefer to have a more involved role in organizing or constructing their home addition. Others simply want to hire a contractor who will handle the entire process. The more involved your contractor is in managing and constructing the project, the more expensive it will be.
3. Product & Material Quality
Nobody wants to build their home addition just to watch it fall apart a year later. However, high-quality materials and craftsmanship for your addition often come at a higher cost.
Frequently Asked Questions
What is Lamont Bros.’ process for a home addition?
As a design-build firm, we work with homeowners to thoroughly plan out their home addition project before moving them to construction. Check out our Process Page to learn more about the design-build experience.
Can you keep the cost of my home addition within my budget?
Absolutely. At Lamont Bros., we’re committed to keeping you in charge of the cost of your home addition. One major benefit of the design-build process is that you’ll know exactly how much your addition will cost before it ever begins construction.
Do you offer financing for home additions?
Although Lamont Bros. does not directly offer financing for home addition, we do partner with several lenders to provide our clients with a variety of financing options. Whether you need $50,000 or $500,000, we’ll work with you to find a lender who meets your financing needs.
How is Lamont Bros. different from other contractors?
Lamont Bros. is a design-build firm, meaning we offer full-process remodeling services and oversee both the design and construction of a remodel. Design-build firms are but one of many types of contractors available to you.
To ensure that you’re able to hire a contractor who meets all of your home addition expectations, check out our 3-Step Guide to Choosing a Remodeling Contractor.
Is a home addition a good investment?
When designed well and kept to a reasonable budget, a home addition can be a great investment in the value of your home and the quality of your life while you live there. Market data suggests that a home addition can add up to 80% of its cost back to the home’s value upon completion.