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Addition to existing structure builders in Sonoma

Avatar for Qualified Builders Construction
Qualified Builders Construction
2206 Oakview Court
5.00(
2
)
Approved Pro
Qualified Builders Construction
2206 Oakview Court
5.00(
2
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
3 years of experience

Customer satisfaction is what determines our success, which is why we take a hands-on approach. When interacting with Qualified Builders Construction, you'll notice that we're particularly focused on the principles of quality workmanship, timely completion, competitive pricing and integrity in all our business dealings. We combine knowledge and research with our extensive practical experience to ensure a specialized approach for your project needs. Contact us today for a fair and accurate estimate of your project. We look forward to adding you to our long and growing list of happy customers.

"Excellent company! Phenomenal work for the price and I am very happy with the fence they built!"

Mark L on January 2023

Customer satisfaction is what determines our success, which is why we take a hands-on approach. When interacting with Qualified Builders Construction, you'll notice that we're particularly focused on the principles of quality workmanship, timely completion, competitive pricing and integrity in all our business dealings. We combine knowledge and research with our extensive practical experience to ensure a specialized approach for your project needs. Contact us today for a fair and accurate estimate of your project. We look forward to adding you to our long and growing list of happy customers.

"Excellent company! Phenomenal work for the price and I am very happy with the fence they built!"

Mark L on January 2023


Avatar for Grid Design Build
Grid Design Build
1500 3rd St, Suite A
New on HomeAdvisorNew on Angi
Approved Pro
Grid Design Build
1500 3rd St, Suite A
New on AngiNew on HomeAdvisor
Approved Pro
3 years of experience
Free onsite estimate

We’re 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 Home Improvement services that are customizable to each individual project. We specialize in Additions and Kitchen 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!

We’re 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 Home Improvement services that are customizable to each individual project. We specialize in Additions and Kitchen 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!


Homes West Construction
P.O. Box 2453
2.75(
3
)
Approved Pro
Homes West Construction
P.O. Box 2453
2.75(
3
)
Approved Pro
23 years of experience
Free onsite estimate

Homes West Construction provides top quality work in the Napa area specializing in structural repairs, remodels and new construction. Our professional crew is proficient in all areas of the building process and are dedicated to delivering an excellent product at a competitive price and in a timely fashion.

"Great contractor. He helped to design and pick out fixtures. Excellent work doing my front porch in three weeks."

Robert P on December 2020

Homes West Construction provides top quality work in the Napa area specializing in structural repairs, remodels and new construction. Our professional crew is proficient in all areas of the building process and are dedicated to delivering an excellent product at a competitive price and in a timely fashion.

"Great contractor. He helped to design and pick out fixtures. Excellent work doing my front porch in three weeks."

Robert P on December 2020


Avatar for Lexicon Construction
Lexicon Construction
20857 Santa Rosa Avenue
5.00(
1
)
Approved Pro
Lexicon Construction
20857 Santa Rosa Avenue
5.00(
1
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
29 years of experience

Lexicon Construction, 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 customers interests, and make their concerns the basis of our business.

"Superior craftsmanship, reliable, always does a good job."

Dean M on May 2023

Lexicon Construction, 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 customers interests, and make their concerns the basis of our business.

"Superior craftsmanship, reliable, always does a good job."

Dean M on May 2023


Concept, Design, Develop, Inc.
PO Box 15035
5.00(
4
)
Approved Pro
Concept, Design, Develop, Inc.
PO Box 15035
5.00(
4
)
Approved Pro
Customers say: Quality work
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
10 years of experience

We take great pride in our experience, expertise, quality, and customer service that we provide to meet the consumer’s 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 did an excellent job! We definitely would want to use them again. They just replaced the siding on the sun beaten part of our house. It looks much better than before and matches the rest of the house perfectly. They were responsive and got things done in a timely manner. I recommend vey highly."

Doug W on May 2024

We take great pride in our experience, expertise, quality, and customer service that we provide to meet the consumer’s 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 did an excellent job! We definitely would want to use them again. They just replaced the siding on the sun beaten part of our house. It looks much better than before and matches the rest of the house perfectly. They were responsive and got things done in a timely manner. I recommend vey highly."

Doug W on May 2024


Millstreet Builders
448 Ignacio Blvd, Unit 193
5.00(
2
)
Approved Pro
Millstreet Builders
448 Ignacio Blvd, Unit 193
5.00(
2
)
Approved Pro
Customers say: Quality work
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
5 years of experience

MILLSTREET BUILDERS is dedicated to providing our customers with the best quality and craftsmanship. We are here to build relationships with our customers and communities and to provide our employees with a great place to work. We look forward to working with you!

"Craig was great to work with! Kept on time and on budget"

Stacey R on November 2023

MILLSTREET BUILDERS is dedicated to providing our customers with the best quality and craftsmanship. We are here to build relationships with our customers and communities and to provide our employees with a great place to work. We look forward to working with you!

"Craig was great to work with! Kept on time and on budget"

Stacey R on November 2023


Robert McCollister Construction Inc
1512 D St
5.00(
3
)
Approved Pro
Robert McCollister Construction Inc
1512 D St
5.00(
3
)
Approved Pro
Customers say: Quick response
12 local quotes requested
15 years of experience

Robert McCollister Construction, 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 customers' interests and make their concerns the basis of our business.

"Robert is a veteran to the contracting business. He is a “salt of the earth” gentleman with an incredible skill set that he utilized to bring our vision to reality. This was a very intricate build, taking a 1940’s cottage and doubling its size while updating absolutely everything. His subcontractors are top notch which matches Robert’s impeccable work ethic. We are absolutely thrilled with the results. "

Patrick Celiberti T on February 2025

Robert McCollister Construction, 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 customers' interests and make their concerns the basis of our business.

"Robert is a veteran to the contracting business. He is a “salt of the earth” gentleman with an incredible skill set that he utilized to bring our vision to reality. This was a very intricate build, taking a 1940’s cottage and doubling its size while updating absolutely everything. His subcontractors are top notch which matches Robert’s impeccable work ethic. We are absolutely thrilled with the results. "

Patrick Celiberti T on February 2025


Cerletti & Kennedy Design-Build
2950 Buskirk Avenue, Suite 300
4.60(
82
)
Approved Pro
Cerletti & Kennedy Design-Build
2950 Buskirk Avenue, Suite 300
4.60(
82
)
Approved Pro
Super Service Award
Customers say: True professional
47 local quotes requested
38 years of experience

SPECIALIZING IN HAPPY CUSTOMERS! Cerletti & Kennedy Design-Build is a full service contractor, family owned and operated for three generations. We specialize in room additions, kitchens and all your remodeling needs. We offer comprehensive design services utilizing the latest 3D CAD technology so you can see your design choices before you build. We're prompt and cost effective, our workers are clean and courteous and our customers are satisfied and happy.

"The job got finished overall I was happy with the finish project. The job was not as smooth I had hoped for. I believe my experience on construction and expectation's might have been out of touch. I would for sure let them bid on more work for me if I ever planned to do any more construction."

Larry P on April 2025

SPECIALIZING IN HAPPY CUSTOMERS! Cerletti & Kennedy Design-Build is a full service contractor, family owned and operated for three generations. We specialize in room additions, kitchens and all your remodeling needs. We offer comprehensive design services utilizing the latest 3D CAD technology so you can see your design choices before you build. We're prompt and cost effective, our workers are clean and courteous and our customers are satisfied and happy.

"The job got finished overall I was happy with the finish project. The job was not as smooth I had hoped for. I believe my experience on construction and expectation's might have been out of touch. I would for sure let them bid on more work for me if I ever planned to do any more construction."

Larry P on April 2025


Advanced Construction Company
4251 Susan Lane
5.00(
3
)
Approved Pro
Advanced Construction Company
4251 Susan Lane
5.00(
3
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
34 years of experience

ACC has been providing residential/commercial remodeling services to Northern CA since 1991. We are reliable, provide detailed estimates and competitive pricing. We are a Certified Green Builder. Advanced Construction Company has been in business since 1991, specializing in residential remodels. During the past 30 years, we have taken pride in providing 100% customer satisfaction through honesty, dependability and quality workmanship. Ed Story (owner/president) has more than 35 years of experience in the construction industry. An innovative problem solver, Ed brings experience and creative insight to every job. Experts in making your visions a reality, we use only quality materials and supplies and consistently work with the same subcontractors. Offering competitive fixed bid prices for any kind of work, ACC is the answer to all of your construction and remodeling needs.

"Very professional and easy to work with."

Carol H on July 2016

ACC has been providing residential/commercial remodeling services to Northern CA since 1991. We are reliable, provide detailed estimates and competitive pricing. We are a Certified Green Builder. Advanced Construction Company has been in business since 1991, specializing in residential remodels. During the past 30 years, we have taken pride in providing 100% customer satisfaction through honesty, dependability and quality workmanship. Ed Story (owner/president) has more than 35 years of experience in the construction industry. An innovative problem solver, Ed brings experience and creative insight to every job. Experts in making your visions a reality, we use only quality materials and supplies and consistently work with the same subcontractors. Offering competitive fixed bid prices for any kind of work, ACC is the answer to all of your construction and remodeling needs.

"Very professional and easy to work with."

Carol H on July 2016


Wadleigh Group, Inc.
214 Club Drive
New on HomeAdvisorNew on Angi
Approved Pro
Wadleigh Group, Inc.
214 Club Drive
New on AngiNew on HomeAdvisor
Approved Pro
10 local quotes requested
18 years of experience

Wadleigh Group, 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 customers' interests, and make their concerns the basis of our business.

Wadleigh Group, 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 customers' interests, and make their concerns the basis of our business.

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Addition to existing structure building services FAQs

How far you can push a room depends on the structure you choose. A cantilevered bump-out can extend 24 inches before building codes require its own footing or foundation. Anything longer needs engineered support and a permit. Check local codes or consult with a structural professional before finalizing plans to ensure your design remains safe and compliant.

Most bump-outs are completed within one to four weeks, even with minimal electrical, plumbing, or HVAC work. Their compact size means less demolition, simpler inspections, and fewer weather-related delays compared to a full-scale addition. Your contractor can provide a more precise timeline once they have determined the scope, materials, and permit schedule, but plan on having the extra square footage ready in approximately a month.

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.
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