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Top-Rated Addition to existing structure builders in Port Jefferson - Updated Nov 2026

Avatar for BuildingLI.com - BLI Facilities LLC
BuildingLI.com - BLI Facilities LLC
5.0(
32
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 2017

Free estimates

Emergency services offered

"Eddie was great to work with! We had a limited time frame to adhere to town inspections and Eddie and his team knew exactly what we needed and quickly got the job done. The results were great and even the inspector acknowledged the impressive repair. They were able to put a knocked out garage wall back on the foundation and repair the interior dry wall. I would recommend this company for any professional contract work due to their reasonable price, ease to work with and quality of work."
before demo
kitchen demolition
demolition complete
kitchen tile job in progress
kitchen tile

+172

Response time7 hrs
Recommended by76%of homeowners
Avatar for Arthur DeRosa Building and Remodeling
Arthur DeRosa Building and Remodeling
4.7(
13
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 1986

Free estimates

Customers say: True professional

"Artie & Mike are simply the best. I used them to: 1) Build a LARGE extension to my house and redo my entire kitchen and dining room. The job was completed on time and on budget. Throughout the process Artie was transparent & professional. EVERY person who has stepped into my house has complimented at the detailed perfection. 3) Artie built us a custom walk in pantry 2) Built 2 large decks in the backyard as well as an outdoor shower. This project was completed on time, on budget while exceeding all expectations. If you are looking for a contractor and crew that is responsible, responsive, polite, creative and delivers the HIGHEST LEVEL of quality - Artie is the one."
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+20

Response time2 days
4 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for Alta Renovations Corp
Alta Renovations Corp
5.0(
30
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

Super Service Award Winner

In business since 2019

Free estimates

Warranties offered

"Jose and his crew did an outstanding job on our extensive interior and exterior renovation, which included a new addition. The project covered everything from a new structural roof with shingles and skylights to new construction windows and doors, siding, a Trex deck, and fully renovated kitchen, bathroom, and laundry room. They also refinished a bedroom and installed beautiful hardwood floors. As with any large project, a few unexpected challenges came up, but Jose handled them with professionalism and kept everything moving forward smoothly. His craftsmanship is excellent, and he’s not only easy to work with but also patient and highly skilled at problem-solving. I wouldn’t hesitate to hire Jose again for future projects and highly recommend him to anyone looking for quality work and a reliable contractor."
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+26

Response time8 hrs
22 neighbors recently requested a quote
Recommended by80%of homeowners
Avatar for A.S.M. Home Improvements
A.S.M. Home Improvements
5.0(
12
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 2021

Free estimates

Credit card accepted

"Anthony is the consummate professional. He worked with us to design a porch that not only looks outstanding but adds curb appeal and value to our home we never could have imagined. He is efficient, neat, completely open to last minute "hey we forgot but could you...", incredibly excellent at everything he does (he's also done for us internal painting, fixed floor planks etc) and most important is that he is just the nicest person with whom to work on home projects. Highly recommend."
Remodeling
Remodeling
Remodeling
Remodeling
2 of 2
fire pit

+48

Response time11 hrs
11 neighbors recently requested a quote
Recommended by58%of homeowners
Avatar for Tri Build Construction
Tri Build Construction
4.2(
40
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

Super Service Award Winner

In business since 1987

Free estimates

Warranties offered

"I am incredibly thankful to Ray LaManna and Tri Build Construction for my new roof. I had major structural damage to my roof due to improperly installed solar panels. Not only did Tri Build diagnose the leaks before the repair, they fixed it in record time. It was extremely reassuring to know what the cause was and how it would be resolved so that I would not have to worry about my home, my greatest investment. If you have roof damage due to improperly installed solar panels, or if you’re looking for a new roof and need a competent and honest contractor, you need Tri Build Construction, a U.S. Veteran owned company."
Response time1 day
4 neighbors recently requested a quote
Recommended by66%of homeowners
Avatar for Patzan Home Improvement Inc
Patzan Home Improvement Inc
5.0(
6
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 2008

Emergency services offered

Customers say: True professional

"We are very happy and satisfied with the projects completed by Patzan at our home. Mr. Patzan is very professional, knowledgeable and pays great attention to detail to deliver a good durable, functional and great look looking finish at a decent price. Mr. Patzan Communication is excellent and he answers all my questions. We did two projects with Patzan and we are planning my our next one with Patzan. I really recommend this company."
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+29

5 neighbors recently requested a quote
Recommended by83%of homeowners
MGT Construction, Corp.
4.1(
17
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

Free estimates

Emergency services offered

Warranties offered

"Excellent - Provider made appointment to go over the work to be completed. He was prompt, courteous & his workers were neat & installed flooring to my satisfaction. He was involved with every step of the project. It was a pleasure working with this provider,"
Greenport Second Floor Addition
Orient Complete Ground up House
Greenport Complete Ground Up House
Kitchen Remodeling Project
Orient Complete House Build - Bathrooms

+172

Response time1 day
3 neighbors recently requested a quote
Recommended by75%of homeowners
Thomas O'Neill Custom Design, Inc.
5.0(
2
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 2016

Free estimates

Credit card accepted

At Thomas O'Neill Custom ,we are dedicated to providing you with exceptional customer service. We specialize in getting your projects done in a timely and professional manner. We have been in business for over 20 years and are backed by over 40+ years experience, and are licensed and insured. So call today and set up your free no obligation estimate. We are located in Southampton NY. Thank you.

Response time2 days
21 neighbors recently requested a quote
Recommended by100%of homeowners
CHELSEA HOME REMODELING INC
5.0(
1
)
Addition to Existing Structure - Build

Serving Port Jefferson, NY and surrounding areas

Approved

In business since 1986

Free estimates

Emergency services offered

"The installers arrived on time, were immaculate and the tile job was perfect. The slab was uneven but they somehow managed to pit in a perfectly level floor. The employees are very pleasant and professional. They came highly recommended by Cancos Tile, which is how I found them."
13 neighbors recently requested a quote
Recommended by100%of homeowners
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FAQs for addition to existing structure building service projects in Port Jefferson, NY

You can typically raise your roof by four to eight feet, depending on your home's structure and roof design. The exact amount depends on factors like roof slope and framing support. Raising the roof creates additional interior space, enhances natural light, and increases your home's value. Consult a professional to determine the feasible height increase for your home.

Yes, you need a building permit to raise your roof. Obtaining a building permit ensures your project complies with local building codes and safety regulations. A professional contractor can assist with the permit and inspection process and ensure all legal and safety requirements are met. Your contractor will be familiar with building codes in your area, which can differ between cities or states.

While it's possible to raise a flat roof, it requires extensive structural modifications. Flat roofs lack the attic space and support structures of pitched roofs, so raising them involves significant engineering to ensure safety and durability. This process can be complex and costly, so professional assessment is essential before undertaking a project of this magnitude.

The Port Jefferson, NY 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.