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Find Addition to existing structure builders in San Francisco

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


RSB Construction Group Inc.

58 W Portal Ave, Unit 150
New on HomeAdvisorNew on HomeAdvisor
Approved Pro

RSB Construction Group Inc.

58 W Portal Ave, Unit 150
New on HomeAdvisorNew 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!


"Hassle free experience."

Sudanshu B on August 2019

Kasas Builders has 6 years in the construction industry. We love working with homeowners and seeing the beautiful finished products that our teams create. We take pride in our work and always strive for perfection. Call Kasas Builders to schedule your free estimate today!

"Hassle free experience."

Sudanshu B on August 2019


Ashbury General Contracting and Engineering

40 12th Street
4.50(
2
)
Approved Pro

Ashbury General Contracting and Engineering

40 12th Street
4.50(
2
)
Approved Pro
Customers say: Terrific value
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
35 years of experience

Mon-Fri 7a-5pm Fully integrated company. All work is done in-house by employees not sub-contractors. 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 forwards to earning your business! Book with us online or feel free to give us a call today!

"Great work for a great price."

Paul H on March 2023

Mon-Fri 7a-5pm Fully integrated company. All work is done in-house by employees not sub-contractors. 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 forwards to earning your business! Book with us online or feel free to give us a call today!

"Great work for a great price."

Paul H on March 2023


Avatar for Level 8 Construction Inc.

Level 8 Construction Inc.

337 12th Ave
5.00(
1
)
Approved Pro

Level 8 Construction Inc.

337 12th Ave
5.00(
1
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
20 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 services that are customizable to each individual project. You will find us to be competitively priced, paying close attention to the details of each and every project that we are involved with. We look forward to building lasting relationships and guarantee your satisfaction!

"I found this company to be very responsive and fair, they were extremely easy to work with, I wold highly recommend them to anybody."

Pete S on August 2020

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 services that are customizable to each individual project. You will find us to be competitively priced, paying close attention to the details of each and every project that we are involved with. We look forward to building lasting relationships and guarantee your satisfaction!

"I found this company to be very responsive and fair, they were extremely easy to work with, I wold highly recommend them to anybody."

Pete S on August 2020


AM GENERAL CONTRACTOR

2341 W Ave #133
5.00(
2
)
Approved Pro

AM GENERAL CONTRACTOR

2341 W Ave #133
5.00(
2
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
22 years of experience

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

"What ever he plans for the project,He compleat that.He is honest and fair.I will refer him to my friends and family."

Mina R on November 2020

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

"What ever he plans for the project,He compleat that.He is honest and fair.I will refer him to my friends and family."

Mina R on November 2020


Avatar for Springs Construction Corporation

Springs Construction Corporation

881 Hurlingame Ave
New on HomeAdvisorNew on HomeAdvisor
Approved Pro

Springs Construction Corporation

881 Hurlingame Ave
New on HomeAdvisorNew 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.


Avatar for T Prior Building Co

T Prior Building Co

2861 WEBSTER ST, APT 4
New on HomeAdvisorNew on HomeAdvisor
Approved Pro

T Prior Building Co

2861 WEBSTER ST, APT 4
New on HomeAdvisorNew on HomeAdvisor
Approved Pro
1 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. 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 Unique Home Design & Remodeling

Unique Home Design & Remodeling

303 Twin Dolphin Dr.
New on HomeAdvisorNew on HomeAdvisor
Approved Pro

Unique Home Design & Remodeling

303 Twin Dolphin Dr.
New on HomeAdvisorNew on HomeAdvisor
Approved Pro
313 local quotes requested
42 years of experience

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. Unique Home Design & Remodeling's mission is to accomplish full customer satisfaction in every area possible from color selection to project completion. Unique Home Design & Remodeling's main focus is to provide our future clients with a professional home improvement experience. We vow to our customers with the highest level of quality construction services at fair market and competitive prices. To ensure the longevity of our company through repeat and referral business achieved by customer satisfaction in all areas including timeliness, attention to detail and service-minded attitudes.

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. Unique Home Design & Remodeling's mission is to accomplish full customer satisfaction in every area possible from color selection to project completion. Unique Home Design & Remodeling's main focus is to provide our future clients with a professional home improvement experience. We vow to our customers with the highest level of quality construction services at fair market and competitive prices. To ensure the longevity of our company through repeat and referral business achieved by customer satisfaction in all areas including timeliness, attention to detail and service-minded attitudes.


Avatar for 360 FULL SERVICE CONSTRUCTION

360 FULL SERVICE CONSTRUCTION

3.67(
3
)
Approved Pro

360 FULL SERVICE CONSTRUCTION

3.67(
3
)
Approved Pro
10 local quotes requested
29 years of experience

360 Full Service Construction delivers exceptional results for residential, commercial, and industrial construction projects. Our skilled team brings innovation, expertise, and attention to detail to every project. We strive to exceed client expectations by delivering projects on time and within budget, regardless of their size and complexity. Contact us to turn your vision into a reality.

"⭐ 1 Star – Unsafe, Unlicensed, and Untrustworthy Contractor I hired Fernando Soto / 360FSC Inc. for an ADU and home extension in Millbrae, and it has been one of the most stressful and costly experiences I’ve ever gone through. From the start, Soto relied on unlicensed workers for critical trades. Electrical work was unsafe and failed inspection — indoor panels were installed outside, wires were left unsecured, and essential safety breakers were missing. Plumbing was just as bad: instead of replacing the pipes as I requested on day one, his crew tied old cast iron, clay, and PVC together, even forcing larger pipes into smaller ones. This caused sewage leaks and backups. Independent inspections later confirmed major issues: Flooring – failed inspection and needs to be completely redone. Foundation – the new extension has already sunk by about 3.5 inches, creating serious structural risks. On top of that, the project stalled for months after May 19th, billing was vague, and Soto even threatened to rip out work I had already paid for. He hides behind a P.O. Box in Belmont instead of a real address, which says a lot about accountability. This contractor cuts corners, uses unlicensed trades, and leaves unsafe work behind. Do not make the mistake I did — avoid Fernando Soto and 360FSC Inc. One more red flag: a glowing “review” on this page was written by Rachel G — who is actually tied to his business. That tells you everything about how much weight to give positive reviews here."

Waifung S on September 2025

360 Full Service Construction delivers exceptional results for residential, commercial, and industrial construction projects. Our skilled team brings innovation, expertise, and attention to detail to every project. We strive to exceed client expectations by delivering projects on time and within budget, regardless of their size and complexity. Contact us to turn your vision into a reality.

"⭐ 1 Star – Unsafe, Unlicensed, and Untrustworthy Contractor I hired Fernando Soto / 360FSC Inc. for an ADU and home extension in Millbrae, and it has been one of the most stressful and costly experiences I’ve ever gone through. From the start, Soto relied on unlicensed workers for critical trades. Electrical work was unsafe and failed inspection — indoor panels were installed outside, wires were left unsecured, and essential safety breakers were missing. Plumbing was just as bad: instead of replacing the pipes as I requested on day one, his crew tied old cast iron, clay, and PVC together, even forcing larger pipes into smaller ones. This caused sewage leaks and backups. Independent inspections later confirmed major issues: Flooring – failed inspection and needs to be completely redone. Foundation – the new extension has already sunk by about 3.5 inches, creating serious structural risks. On top of that, the project stalled for months after May 19th, billing was vague, and Soto even threatened to rip out work I had already paid for. He hides behind a P.O. Box in Belmont instead of a real address, which says a lot about accountability. This contractor cuts corners, uses unlicensed trades, and leaves unsafe work behind. Do not make the mistake I did — avoid Fernando Soto and 360FSC Inc. One more red flag: a glowing “review” on this page was written by Rachel G — who is actually tied to his business. That tells you everything about how much weight to give positive reviews here."

Waifung S on September 2025

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FAQs for addition to existing structure building service projects in San Francisco, CA

Yes, hidden rooms are legal, as long as they meet all local building regulations. If you sell your house, most states require homeowners to disclose full houseplans, which would include any hidden rooms.

If your secret room is a safe room, it should contain a means of communication aside from a cell phone, such as a shortwave radio. You should also have plenty of drinking water, a portable generator, emergency food supplies, blankets, pillows, flashlights, batteries and a first aid kit.

Any time you update your home’s square footage, you increase its value, but a secret room is a niche feature that doesn't rank high on every buyer’s list of must-haves. Investing your money in remodeling more common living areas like bedrooms, bathrooms, or kitchens will have a higher ROI than adding a secret room. Many secret rooms can act as entertainment spaces (think a game room or wine cellar) or quiet spaces (a library or study), so when building your secret room you may want to consider its versatility for when you’re ready to sell.

The San Francisco, CA 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.