Top-rated addition to existing structure builders.

Get matched with top addition to existing structure builders in your area

Enter your zip and get matched with up to 3 pros

Matching on HomeAdvisor

Share some details icon
Share some details about your home project.
Match with local pros icon
Within moments, match with highly-rated local pros.
Compare quotes icon
Compare quotes and choose the best pro for the job.

Addition to existing structure builders in Portola Valley

Avatar for Unique Home Design & Remodeling
Unique Home Design & Remodeling
303 Twin Dolphin Drive, 6th Floor
4.83(
33
)
Approved Pro
Unique Home Design & Remodeling
303 Twin Dolphin Drive, 6th Floor
4.83(
33
)
Approved Pro
Customers say: Quick response
Recommended by 96% of Angi customers
Recommended by 96% of HomeAdvisor customers
27 local quotes requested

Unique Home Design & Remodeling is a leader in providing value-added construction services to our customers by creating a successful partnership throughout the construction process. Our pledge is to establish lasting relationships with our customers by exceeding their expectations and gaining their trust through exceptional performance by every member on our construction team.

"Deeply Disappointed ? Poor Execution, Lack of Communication, and Mismanagement I hired Unique Home Design & Remodel around August/September for a major home renovation project?an ~800 sqft addition and kitchen remodel. Unfortunately, the experience has been nothing short of frustrating and disappointing. From the very beginning, it was clear that Unique overpromises and severely underdelivers. The project manager, Tal Barun, and the subcontractor, Rafael, failed to maintain even the most basic level of professionalism. Once the work began, we heard nothing from Unique unless it was about collecting checks. No weekly updates, no clear plans, and a lot of confusion. Communication was abysmal?we had to chase them down for responses that came days later, if at all. The craftsmanship? Poor at best. The subcontractor appeared completely unprepared and unequipped to handle a project of this size. We were essentially left to deal with Rafael directly, which made things even worse. Foundation"

Kartik M on April 2025

Unique Home Design & Remodeling is a leader in providing value-added construction services to our customers by creating a successful partnership throughout the construction process. Our pledge is to establish lasting relationships with our customers by exceeding their expectations and gaining their trust through exceptional performance by every member on our construction team.

"Deeply Disappointed ? Poor Execution, Lack of Communication, and Mismanagement I hired Unique Home Design & Remodel around August/September for a major home renovation project?an ~800 sqft addition and kitchen remodel. Unfortunately, the experience has been nothing short of frustrating and disappointing. From the very beginning, it was clear that Unique overpromises and severely underdelivers. The project manager, Tal Barun, and the subcontractor, Rafael, failed to maintain even the most basic level of professionalism. Once the work began, we heard nothing from Unique unless it was about collecting checks. No weekly updates, no clear plans, and a lot of confusion. Communication was abysmal?we had to chase them down for responses that came days later, if at all. The craftsmanship? Poor at best. The subcontractor appeared completely unprepared and unequipped to handle a project of this size. We were essentially left to deal with Rafael directly, which made things even worse. Foundation"

Kartik M on April 2025


Avatar for G M J Construction Inc.
G M J Construction Inc.
2582 Amethyst Drive
5.00(
13
)
Approved Pro
G M J Construction Inc.
2582 Amethyst Drive
5.00(
13
)
Approved Pro
Super Service Award
Customers say: Quick response
Recommended by 92% of Angi customers
Recommended by 92% of HomeAdvisor customers
11 years of experience

GMJ construction Is one of the best construction company in the bay area, we focus on providing our customers A Great experience, we provide high-quality project management and excellent finish Work, We are design and build firm,We specialize in new construction home, room addition, kitchen, bathroom and custom work , Feel free to contact us today for a free consultation meeting with one of our great project managers

"GMJ is the perfect spot if you are after an outstanding Eichler home. Joseph communication skills are top-notch, and he understood my needs perfectly. They have incredibly creative and brilliant minds and really grasp what the customer desires. Thanks a bunch, Joseph, for all your assistance! I highly recommend this company to anyone in search of the best Eichler Contractor in Sunnyvale!"

Mike K on May 2024

GMJ construction Is one of the best construction company in the bay area, we focus on providing our customers A Great experience, we provide high-quality project management and excellent finish Work, We are design and build firm,We specialize in new construction home, room addition, kitchen, bathroom and custom work , Feel free to contact us today for a free consultation meeting with one of our great project managers

"GMJ is the perfect spot if you are after an outstanding Eichler home. Joseph communication skills are top-notch, and he understood my needs perfectly. They have incredibly creative and brilliant minds and really grasp what the customer desires. Thanks a bunch, Joseph, for all your assistance! I highly recommend this company to anyone in search of the best Eichler Contractor in Sunnyvale!"

Mike K on May 2024


Avatar for Royalty Builders, Inc.
Royalty Builders, Inc.
228 Hamilton Ave 3rd Floor
5.00(
14
)
Approved Pro
Royalty Builders, Inc.
228 Hamilton Ave 3rd Floor
5.00(
14
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
25 years of experience

Royalty Builders Inc is committed to excellence in every aspect of our business. We uphold a standard of integrity bound by fairness, honesty, and personal responsibility. Our distinction is the quality of service we bring to our customers. Accurate knowledge of our trade combined with ability is what makes us true professionals. Above all, we are watchful of our customer's interests and make their concerns the basis of our business. Please give us a call today 855-744-4424

"Bathroom remodeling Panel upgrade I want to tank royalty builders for the new bathroom the design and the crew was great we are happy with out new bathroom"

Vilma T on June 2024

Royalty Builders Inc is committed to excellence in every aspect of our business. We uphold a standard of integrity bound by fairness, honesty, and personal responsibility. Our distinction is the quality of service we bring to our customers. Accurate knowledge of our trade combined with ability is what makes us true professionals. Above all, we are watchful of our customer's interests and make their concerns the basis of our business. Please give us a call today 855-744-4424

"Bathroom remodeling Panel upgrade I want to tank royalty builders for the new bathroom the design and the crew was great we are happy with out new bathroom"

Vilma T on June 2024


Avatar for Square Three, Inc.
Square Three, Inc.
830 Stewart Dr #272
4.92(
6
)
Approved Pro
Square Three, Inc.
830 Stewart Dr #272
4.92(
6
)
Approved Pro
Customers say: Quality work
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
10 years of experience

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. Our senior team has 10-20 years of experience specifically in the SF Bay Area. We look forward to earning your business! Book with us online or feel free to give us a call today!

"Sanjeev has a solid team working for him that is very capable and deliver quality work. Very flexible and always trying to accommodate our needs even with unexpected changes to the project plan. Highly recommended."

Jannik O on April 2022

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. Our senior team has 10-20 years of experience specifically in the SF Bay Area. We look forward to earning your business! Book with us online or feel free to give us a call today!

"Sanjeev has a solid team working for him that is very capable and deliver quality work. Very flexible and always trying to accommodate our needs even with unexpected changes to the project plan. Highly recommended."

Jannik O on April 2022


Universal Construction Company
161 Martin Place
4.71(
7
)
Approved Pro
Universal Construction Company
161 Martin Place
4.71(
7
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
45 years of experience

We are a locally owned and operated company that values honesty and integrity, and treats your home as if it were our own. We offer a variety of general contractor and home improvement services that are customizable to each individual project. We specialize in additions and bathroom remodels, but also offer a wide range of expertise for a variety of other projects. We pride ourselves on the quality of our work, as well as our commitment to outstanding results. We look forward to building lasting relationships, and guarantee your satisfaction!

"He is very good, communicates well, and he is there when he says he will be and very thorough! I liked doing business with him! He explains everything that he will do before he does the job and he listens to my suggestions."

Marilyn B on June 2019

We are a locally owned and operated company that values honesty and integrity, and treats your home as if it were our own. We offer a variety of general contractor and home improvement services that are customizable to each individual project. We specialize in additions and bathroom remodels, but also offer a wide range of expertise for a variety of other projects. We pride ourselves on the quality of our work, as well as our commitment to outstanding results. We look forward to building lasting relationships, and guarantee your satisfaction!

"He is very good, communicates well, and he is there when he says he will be and very thorough! I liked doing business with him! He explains everything that he will do before he does the job and he listens to my suggestions."

Marilyn B on June 2019


Avatar for Masterful Construction, Inc.
Masterful Construction, Inc.
3 East Third Avenue, #340
5.00(
22
)
Approved Pro
Masterful Construction, Inc.
3 East Third Avenue, #340
5.00(
22
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
2 years of experience

MASTERFUL CONSTRUCTION INC is the leader in providing our customers with the highest quality service in an honest, efficient, and professional way. Our pledge is to create successful relationships with our customers, employees and community by building trust, treating every project with the utmost integrity and exceeding expectations. We look forward to working with you!

"Masterful Constructions architectural and engineering expertise is unparalleled. Their attention to detail and commitment to delivering projects on time and within budget is truly impressive. Every aspect of our project was flawlessly executed."

Ben E on August 2023

MASTERFUL CONSTRUCTION INC is the leader in providing our customers with the highest quality service in an honest, efficient, and professional way. Our pledge is to create successful relationships with our customers, employees and community by building trust, treating every project with the utmost integrity and exceeding expectations. We look forward to working with you!

"Masterful Constructions architectural and engineering expertise is unparalleled. Their attention to detail and commitment to delivering projects on time and within budget is truly impressive. Every aspect of our project was flawlessly executed."

Ben E on August 2023


RSB Construction Group Inc.
58 W Portal Ave, Unit 150
New on HomeAdvisorNew on Angi
Approved Pro
RSB Construction Group Inc.
58 W Portal Ave, Unit 150
New on AngiNew on HomeAdvisor
Approved Pro
4 years of experience
Free onsite estimate

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. We look forward to earning your business!

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. We look forward to earning your business!


Avatar for Aria Custom Home Builder
Aria Custom Home Builder
6376 Mayo Drive
5.00(
2
)
Approved Pro
Aria Custom Home Builder
6376 Mayo Drive
5.00(
2
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
19 years of experience

We take great pride in our experience, expertise, quality and customer service that we provide to meet the consumers needs. It is our mission to provide excellent workmanship and complete customer satisfaction from start to completion of a project. In order to understand the needs and expectations of our customers, we take great care to work and communicate with every customer in a professional manner. Our reputation is based on service, safety and quality, regardless of how large or small the job.

"They responded in a timely manner and were able to get the job done quickly to the date we asked with great expertise work. We were very satisfied and will use them again for another project."

Sheri A on October 2019

We take great pride in our experience, expertise, quality and customer service that we provide to meet the consumers needs. It is our mission to provide excellent workmanship and complete customer satisfaction from start to completion of a project. In order to understand the needs and expectations of our customers, we take great care to work and communicate with every customer in a professional manner. Our reputation is based on service, safety and quality, regardless of how large or small the job.

"They responded in a timely manner and were able to get the job done quickly to the date we asked with great expertise work. We were very satisfied and will use them again for another project."

Sheri A on October 2019


Avatar for ICON Home Builders, Inc.
ICON Home Builders, Inc.
2375 Zanker Rd, Suite 225
5.00(
2
)
Approved Pro
ICON Home Builders, Inc.
2375 Zanker Rd, Suite 225
5.00(
2
)
Approved Pro
Customers say: Quick response
2 years of experience
Free onsite estimate

ICON Home Builders is a full-service general contractor specializing in high-quality home remodels, renovations, and custom builds in the San Francisco Bay Area. We transform homes with custom kitchens, luxurious bathrooms, full renovations, and home additions, combining expert craftsmanship and personalized design. Known for our attention to detail, clear communication, and efficient project management, we ensure your home reflects your vision. We serve Santa Clara, San Mateo, Alameda, and Contra Costa counties, and are EPA Lead-Safe Certified and CSLB Licensed (#1102095). Whether you're looking for a complete home transformation or a specific remodel, ICON Home Builders delivers on time and within budget, ensuring the highest standards in every project.

"Danny's expertise shone through from our very first meeting, where he presented an impressive initial design that immediately instilled confidence in the project's outcome. His meticulous planning and efficient execution made the process nearly effortless for me. Throughout the project, Danny demonstrated exceptional professionalism: He patiently addressed all my questions, ensuring I felt informed and comfortable with each decision. He took charge of the shopping process, offering valuable professional advice on material selections. When the initially chosen tile color didn't translate well from the store to my home, Danny proactively brought a sample for us to evaluate in situ. This attention to detail allowed us to pivot and select a more suitable option that enhanced the overall aesthetic. The final result exceeded my expectations, with Danny's design acumen particularly evident in the enlarged shower space. His thoughtful approach to space utilization has significantly improved the functionality and appeal of the room. Danny's combination of design talent, project management skills, and client-focused service resulted in a fantastic outcome that I'm thrilled with"

Yu Z on September 2024

ICON Home Builders is a full-service general contractor specializing in high-quality home remodels, renovations, and custom builds in the San Francisco Bay Area. We transform homes with custom kitchens, luxurious bathrooms, full renovations, and home additions, combining expert craftsmanship and personalized design. Known for our attention to detail, clear communication, and efficient project management, we ensure your home reflects your vision. We serve Santa Clara, San Mateo, Alameda, and Contra Costa counties, and are EPA Lead-Safe Certified and CSLB Licensed (#1102095). Whether you're looking for a complete home transformation or a specific remodel, ICON Home Builders delivers on time and within budget, ensuring the highest standards in every project.

"Danny's expertise shone through from our very first meeting, where he presented an impressive initial design that immediately instilled confidence in the project's outcome. His meticulous planning and efficient execution made the process nearly effortless for me. Throughout the project, Danny demonstrated exceptional professionalism: He patiently addressed all my questions, ensuring I felt informed and comfortable with each decision. He took charge of the shopping process, offering valuable professional advice on material selections. When the initially chosen tile color didn't translate well from the store to my home, Danny proactively brought a sample for us to evaluate in situ. This attention to detail allowed us to pivot and select a more suitable option that enhanced the overall aesthetic. The final result exceeded my expectations, with Danny's design acumen particularly evident in the enlarged shower space. His thoughtful approach to space utilization has significantly improved the functionality and appeal of the room. Danny's combination of design talent, project management skills, and client-focused service resulted in a fantastic outcome that I'm thrilled with"

Yu Z on September 2024


Avatar for Springs Construction Corporation
Springs Construction Corporation
881 Hurlingame Ave
New on HomeAdvisorNew on Angi
Approved Pro
Springs Construction Corporation
881 Hurlingame Ave
New on AngiNew on HomeAdvisor
Approved Pro
66 years of experience
Free onsite estimate

Since 1959, Springs Construction has built its reputation on fine craftsmanship, technical expertise and solid project management.We take a proactive, client driven approach to every one of our projects, exceeding our customers vision for their homes. We want you to feel comfortable and safe during the disruption and enjoy your home for years to come.

Since 1959, Springs Construction has built its reputation on fine craftsmanship, technical expertise and solid project management.We take a proactive, client driven approach to every one of our projects, exceeding our customers vision for their homes. We want you to feel comfortable and safe during the disruption and enjoy your home for years to come.

...
Showing 1-10 of 992

Addition to existing structure building services FAQs

Building an in-law suite takes between two and seven months. Converting an existing basement, attic, or room can be done in about two months. Constructing a new addition or detached suite often takes four to five months for construction, plus one to two months for permits. The bigger the suite, the longer it will take. 

Yes, you can build an in-law suite in your backyard if you meet local building codes and zoning regulations. An in-law suite often occupies 300 to 800 square feet. Be sure to follow size restrictions, utility separations, and entrance requirements. Hiring a qualified contractor ensures you meet all regulatory requirements because they can pull permits, double-check local code, and gather other skilled pros to work on your suite. 

The homeowners guide to addition to existing structure building services
From average costs to expert advice, get all the answers you need to get your job done.
BRIGHT OPEN ATTIC SPACE
Apr 24, 2025
Apr 24, 2025
An in-law suite is a great solution for people who have family visiting often. Explore how much an in-law suite costs and prep to build yours.
A white wood ceiling
Apr 23, 2025
Apr 23, 2025
Looking to vault a ceiling? Here’s how much it costs, what factors affect cost, and what to expect.
Outdoor view of the modern house
Apr 22, 2025
Apr 22, 2025
Explore how square footage, room type, home additions, and other common factors affect house renovation costs with our detailed cost guide.
A rustic wooden cabin in the woods
Apr 21, 2025
Apr 21, 2025
Discover how much a log cabin costs to build, exploring how factors like its size, site prep, utilities, finishes, and labor rates affect the total price.
CONTRACTOR LOOKING OVER HOME DEVELOPMENT
Apr 19, 2025
Apr 19, 2025
Budget for your general contractor’s hourly rate by considering factors such as project scope, fee structure, pricing model, and more.
stucco home with cracks from earthquake damage
Apr 16, 2025
Apr 16, 2025
Work out the full cost to repair earthquake damage based on the type of damage, including foundation issues, utility lines, and cracked walls.
Share project details to get started.