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 Holtsville

Atlantic Shore Builders & Developers
156 East Main Street
5.00(
3
)
Approved Pro
Atlantic Shore Builders & Developers
156 East Main Street
5.00(
3
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
16 local quotes requested

We are 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. We are watchful of our customer's interests and make their concerns the basis of our business. Give us a call for a quote today!

"Friendly, low price, and best of all the painter, Francisco, is a REAL professional who’s not about doing a slipshod job and leaving. He took as many days as he needed at a flat rate and ensured the job was top quality."

Alexander M on October 2021

We are 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. We are watchful of our customer's interests and make their concerns the basis of our business. Give us a call for a quote today!

"Friendly, low price, and best of all the painter, Francisco, is a REAL professional who’s not about doing a slipshod job and leaving. He took as many days as he needed at a flat rate and ensured the job was top quality."

Alexander M on October 2021


American Home and Design, Inc.
47 Chestnut Avenue
5.00(
23
)
Approved Pro
American Home and Design, Inc.
47 Chestnut Avenue
5.00(
23
)
Approved Pro
Customers say: Quality work
25 years of experience
Free onsite estimate

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

"He has been fantastic!"

Chris P on June 2020

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

"He has been fantastic!"

Chris P on June 2020


Avatar for Exterior Team Home Services, Inc.
Exterior Team Home Services, Inc.
359 North Ocean Avenue Apt. 1
4.95(
22
)
Approved Pro
Exterior Team Home Services, Inc.
359 North Ocean Avenue Apt. 1
4.95(
22
)
Approved Pro
Customers say: Quality work
Recommended by 95% of Angi customers
Recommended by 95% of HomeAdvisor customers
9 years of experience

Exterior Team Home Services, Inc takes 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. Call Exterior Team Home Services, Inc today!

"Ronald and his Team did an excellent job for a very good price. Very professional. Pointed out some things that needed attention and then took care of it. The workmanship and customer service is better than any other craftman I have ever hired. I will keep Exterior Team Home Service number available to recommend to anyone that asks if "I know someone who...." I trust Exterior Team Home and will use them in the future."

Ed S on September 2023

Exterior Team Home Services, Inc takes 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. Call Exterior Team Home Services, Inc today!

"Ronald and his Team did an excellent job for a very good price. Very professional. Pointed out some things that needed attention and then took care of it. The workmanship and customer service is better than any other craftman I have ever hired. I will keep Exterior Team Home Service number available to recommend to anyone that asks if "I know someone who...." I trust Exterior Team Home and will use them in the future."

Ed S on September 2023


DCS Custom Builder, LLC
195 S Gillette Ave
5.00(
3
)
Approved Pro
DCS Custom Builder, LLC
195 S Gillette Ave
5.00(
3
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
18 years of experience

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!

"I hired DCS to renovate a house for my mother. They had to re-frame walls, move doorways, gut reno 2 bathrooms and the kitchen. They finished the drywall, installed the new tile and cabinets, replaced flooring, and installed a new tile fireplace surround and built a custom wood mantle. Great carpenters. Dick Strine, the principal, is so knowledgeable and thorough. If he can figure out where a problem is coming from in your house, no one can. Great customer service. They have also worked for my in-laws, including building one very large house and renovating another."

Jacqueline P on January 2024

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!

"I hired DCS to renovate a house for my mother. They had to re-frame walls, move doorways, gut reno 2 bathrooms and the kitchen. They finished the drywall, installed the new tile and cabinets, replaced flooring, and installed a new tile fireplace surround and built a custom wood mantle. Great carpenters. Dick Strine, the principal, is so knowledgeable and thorough. If he can figure out where a problem is coming from in your house, no one can. Great customer service. They have also worked for my in-laws, including building one very large house and renovating another."

Jacqueline P on January 2024


Coastal Carpentry Corp.
110 Woodcut Drive
5.00(
1
)
Approved Pro
Coastal Carpentry Corp.
110 Woodcut Drive
5.00(
1
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
7 years of experience

Coastal Carpentry Corp, 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.

"They were very easy to work with and I enjoyed their company."

Chad N on July 2021

Coastal Carpentry Corp, 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.

"They were very easy to work with and I enjoyed their company."

Chad N on July 2021


Kiwi Restorations, LLC
194 Mill Road
5.00(
2
)
Approved Pro
Kiwi Restorations, LLC
194 Mill Road
5.00(
2
)
Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
2 years of experience

We are 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.

"Shane and his crew were fantastic. From our first meeting through completion the renovation was seamless. Great attention to detail, neat, clean and respectful of my house. Finished on time and on budget. Highly recommended."

Mark K on February 2024

We are 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.

"Shane and his crew were fantastic. From our first meeting through completion the renovation was seamless. Great attention to detail, neat, clean and respectful of my house. Finished on time and on budget. Highly recommended."

Mark K on February 2024


Avatar for Granville House Victorians L.L.C.
Granville House Victorians L.L.C.
16 Riverdale Ave
5.00(
1
)
Approved Pro
Granville House Victorians L.L.C.
16 Riverdale 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

The linkedin site will tell our Story. Clients will take advantage of Granville's in house Design capabilities with CAD. see granvillevictorians.com for examples of our work

"Granville House Victorians L.L.C. is extremely skilled and professional. My Victorian style house came out better than I could have dreamed. Granville took care of everything and they are extremely knowledgeable in what they do."

Jonathan P on January 2023

The linkedin site will tell our Story. Clients will take advantage of Granville's in house Design capabilities with CAD. see granvillevictorians.com for examples of our work

"Granville House Victorians L.L.C. is extremely skilled and professional. My Victorian style house came out better than I could have dreamed. Granville took care of everything and they are extremely knowledgeable in what they do."

Jonathan P on January 2023


Concorde Remodeling, Inc.
8 Lynam Court
4.69(
41
)
Approved Pro
Concorde Remodeling, Inc.
8 Lynam Court
4.69(
41
)
Approved Pro
Super Service Award
Customers say: Quick response
Recommended by 92% of Angi customers
Recommended by 92% of HomeAdvisor customers
17 years of experience

We are a locally owned and operated company serving the Long Island area. We are committed to excellence in everything we do. Remodeling is our passion and customer service is our specialty. Please call Concorde Remodeling, Inc., today! *DOES NOT HANDLE INSURANCE CLAIMS *

"I recently had the pleasure of working with Bob from Concorde on the finishing of a basement into an apartment, and I am thrilled with the results. From start to finish, the entire process was handled with remarkable professionalism and attention to detail. **Project Management:** Rob, the project manager, was outstanding. He maintained excellent communication throughout the project, keeping me informed of progress and any potential issues. **Quality of Work:** The quality of work delivered by Concorde was exceptional. Every aspect of the construction was executed to the highest standards, from the foundation to the final touches. **Overall Experience:** Overall, my experience with Concorde was nothing short of excellent. They delivered a high-quality construction project that met all my expectations and more. I highly recommend Concorde for any construction needs and will certainly consider them for future projects."

Chrysanthy P on May 2024

We are a locally owned and operated company serving the Long Island area. We are committed to excellence in everything we do. Remodeling is our passion and customer service is our specialty. Please call Concorde Remodeling, Inc., today! *DOES NOT HANDLE INSURANCE CLAIMS *

"I recently had the pleasure of working with Bob from Concorde on the finishing of a basement into an apartment, and I am thrilled with the results. From start to finish, the entire process was handled with remarkable professionalism and attention to detail. **Project Management:** Rob, the project manager, was outstanding. He maintained excellent communication throughout the project, keeping me informed of progress and any potential issues. **Quality of Work:** The quality of work delivered by Concorde was exceptional. Every aspect of the construction was executed to the highest standards, from the foundation to the final touches. **Overall Experience:** Overall, my experience with Concorde was nothing short of excellent. They delivered a high-quality construction project that met all my expectations and more. I highly recommend Concorde for any construction needs and will certainly consider them for future projects."

Chrysanthy P on May 2024


Avatar for East End Designs, LLC
East End Designs, LLC
11 Bridal Path
4.92(
39
)
Approved Pro
East End Designs, LLC
11 Bridal Path
4.92(
39
)
Approved Pro
Super Service Award
Customers say: Quality work
15 years of experience
Free onsite estimate

For over 20 years, Shawn Piazza, the owner of East End Designs, LLC has been providing top quality renovations to the East End and throughout Suffolk County. The team at East End Designs has the capability and knowledge to bring your dream project from an idea to completion. Please call 631-565-1117 or email leanna@eastenddesigns.net to book your free consultation today.

"Incredible work ethic, quality. Had many innovative solutions, delivered on time and exceeded expectations. Project came in on time, on budget. Made was could have been a complicated project a great experience. "

D R on April 2025

For over 20 years, Shawn Piazza, the owner of East End Designs, LLC has been providing top quality renovations to the East End and throughout Suffolk County. The team at East End Designs has the capability and knowledge to bring your dream project from an idea to completion. Please call 631-565-1117 or email leanna@eastenddesigns.net to book your free consultation today.

"Incredible work ethic, quality. Had many innovative solutions, delivered on time and exceeded expectations. Project came in on time, on budget. Made was could have been a complicated project a great experience. "

D R on April 2025


CLM VENTURE CONTRACTING
147-15 Weller Ln
5.00(
7
)
Approved Pro
CLM VENTURE CONTRACTING
147-15 Weller Ln
5.00(
7
)
Approved Pro
Super Service Award
Customers say: Quick response
11 years of experience
Free onsite estimate

CLM VENTURE CONTRACTING 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.

"Great work done for my family! Definitely, would hire again for the job! Thank you so much to the business. It is much appreciated!"

Jessy D on October 2024

CLM VENTURE CONTRACTING 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.

"Great work done for my family! Definitely, would hire again for the job! Thank you so much to the business. It is much appreciated!"

Jessy D on October 2024

...
Showing 1-10 of 949

Addition to existing structure building services FAQs

Most ADU projects require several months from initial planning through final inspection. The timeline includes designing plans, securing permits, site preparation, construction, and finishing work. 

Factors affecting duration include project complexity, contractor availability, weather conditions, and local permitting processes. Planning for potential delays due to material shortages or inspection scheduling is advisable when establishing your project timeline.

Homeowners can access various funding sources for ADU projects. Home equity loans and lines of credit leverage existing property value, while construction loans provide phased funding specifically for building projects. Some areas offer specialized ADU financing programs with favorable terms. 

Personal loans might work for smaller conversions, though they often carry higher interest rates. Your financial situation, credit profile, and project scope will determine which option provides the most advantageous terms.

Adding an ADU often increases your property's assessed value, resulting in higher tax obligations. The specific impact varies by location, as assessment methods and tax rates differ between jurisdictions. Some areas offer temporary exemptions or gradual increases to ease the financial transition. 

For accurate projections, consult your local tax assessor before beginning construction to understand how your specific project will affect future tax bills.

Short-term rental regulations vary dramatically between municipalities. Some jurisdictions permit vacation rentals with minimal restrictions, while others impose occupancy limits, licensing requirements, or outright prohibitions, particularly for ADUs. Many areas require owner occupancy of the primary residence when renting an ADU short-term. 

Research your local ordinances thoroughly before planning rental income, as non-compliance penalties can be substantial.

The ADU construction process frequently encounters obstacles, including complex permitting requirements, unexpected site conditions requiring additional work, contractor scheduling difficulties, and budget management challenges. Many homeowners underestimate the complexity of coordinating multiple specialized trades. 

Additionally, ensuring adequate privacy between the main residence and ADU while maintaining aesthetic cohesion requires careful planning. Thorough preparation and working with experienced professionals can help navigate these common pitfalls.

Identifying qualified ADU contractors requires targeted research. Begin by seeking recommendations from neighbors with completed ADU projects or contacting local builder associations for specialist referrals. Review contractors' portfolios specifically for ADU or small residential projects similar to your vision. 

When interviewing potential candidates, assess their familiarity with local ADU regulations, ask about recent similar projects, and request contact information for past clients with comparable projects.

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.
built-in outdoor kitchen with grill and sink
Apr 30, 2025
Apr 30, 2025
Budget for outdoor kitchen costs based on factors such as appliances, materials, permits, labor, amenities, kitchen size, customizations, and more.
BLUE TWO STORY HOME
Apr 30, 2025
Apr 30, 2025
Budget for the cost to add a second story based on factors such as size, foundation work, materials, labor, permits, post-construction cleaning, and more.
small bathroom that has been updated in a remodel
Apr 29, 2025
Apr 29, 2025
Budget for the cost to remodel a small bathroom based on factors such as required fixtures, bathroom size, labor, remodel type, site prep, and more.
guest house in the backyard
Apr 27, 2025
Apr 27, 2025
Need to build a guest house? Here’s how much it costs, what factors affect cost, and what to expect.
Kitchen view leading into dining area
Apr 28, 2025
Apr 28, 2025
Use this guide to budget for bump-out addition costs based on factors such as room size, room type, labor, finishes, permits, and more.
House roof with nice window
Apr 28, 2025
Apr 28, 2025
Budget for dormer addition costs based on factors such as roof type, framing, customizations, reinforcement, cladding, labor, and more.
Share project details to get started.