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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

"My husband and I are so happy with our new deck. Just in time for the beautiful weather! We have Jose Diaz with Alta renovations corp. to thank for making our home improvement job stress free. He and his crew were extremely prompt, meticulous, courteous and great communicators. Jose made me feel comfortable asking questions and was prompt to respond. It was truly an absolute pleasure working with them from the start to the finish !"
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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

"Absolutely, I’d be happy to help you out with that review! Here’s a glowing one for Tri Build Construction and Ray: --- I recently had the pleasure of working with Tri Build Construction, led by Ray, and I can't say enough great things about the experience. From start to finish, the work was absolutely fantastic. Ray and his team were the epitome of professionalism: they arrived on time, communicated clearly, and maintained a clean and organized workspace every single day. Not only was the craftsmanship top-notch, but the attention to detail really stood out. They took the time to ensure everything was done exactly as we envisioned and even went above and beyond to accommodate a few last-minute tweaks we requested. The final result was everything we hoped for and more. In short, if you're looking for a reliable, skilled, and incredibly professional construction team, I highly recommend Tri Build Construction and Ray. They truly deliver a five-star experience!"
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

"Giovanni and his crew were very professional and did a wonderful renovation to my garage. Any question or concerns I had were answered to my satisfaction . I would highly recommend them for any work you may have. Mike B"
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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

"MGT Construction Corporation was everything I wanted and more. They were prompt. The work was high quality. Steve Kaplan, Mario, Steve, et al were very professional and easy to work with. Steve Kaplan was excellent in following through with everything. The price was excellent. They were very knowledgeable and understood design. After it was finished, Steve followed through on offers to do some additional work as a client courtesy."
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.