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

Avatar for Pristine Construction Inc
Pristine Construction Inc
4.9(
212
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 1997

Free estimates

Emergency services offered

"Pristine Construction just completed a kitchen remodel for us this December. The project was finished on time even though additional projects were added along the way. Everybody from Pristine Construction did their job in the most professional and honest way possible. Through Angie’s List reviews, I came to know their reputation. And these reviews helped me to contact Pristine. The reviews were written in a way that I saw and experienced personally the good things about Pristine Construction. My wife and I were impressed from the start. Nathan and Mike listened to our needs and tried their very best to fulfill them. In my opinion, the crews and staff are the best in their field of expertise. Throughout the project, not only our 1950s-built house had kitchen upgrade, but also had other upgrades done. These other upgrades were done without sacrificing the timeline of the project. My family are all thrilled with the result of the project. I am proud and right in choosing Pristine Construction. I will choose them again on my next home improvement projects."
Additional Photos
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+16

Response time7 hrs
6 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for KN Remodeling & Supplies Inc
KN Remodeling & Supplies Inc
4.8(
63
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2012

Free estimates

Warranties offered

"Working with Nathan & KN Remodeling was the best decision we made when undertaking our garage conversion job. Nathan understood exactly what we wanted, knew our budget parameters and provided us with a range of options that helped us stay within what we were seeking to spend. We wanted it to be NICE, but didn't need to over-do any of the finishes and spend needlessly on areas that were going to be used in-frequently. The end result was fantastic. The workmanship was of the highest order, the job was executed efficiently and with constant communication and oversight. The whole job was stress free and delivered on time. I can't recommend KN Remodeling highly enough!"
Additional Photos
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+48

Response time8 hrs
Response rate100%
5 neighbors recently requested a quote
Avatar for Creative Home Remodeling Group Inc.
Creative Home Remodeling Group Inc.
4.7(
257
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

Super Service Award Winner

In business since 2003

Free estimates

Warranties offered

"If you need an addition built on your house, I'd highly recommend you give Creative Remodeling a call. We used them to add a master suite which makes our house much more livable. We've also decided to add decking in the back yard off the the back of the house. Oh, and this was after working with them during Covid on a kitchen and 2 bathrooms. So that makes us repeat, on repeat, on repeat customers. The work is quick, to a good quality, and they listen to what the customer wants and have dealt with the odd snafu without any push back. Highly recommended."
Complete Kitchen with White and Blue Cabinets
Complete Kitchen Modern Kitchen With Botcher Island
posses of the kitchen remodeling
Modern ADU, large space with studio and 1 bathroom, big windows
White Kitchen Cabinets

+427

Response time1 day
Response rate100%
7 neighbors recently requested a quote
Avatar for HIC Builders, Inc.
HIC Builders, Inc.
5.0(
12
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2017

Free estimates

Warranties offered

"HIC builders is a family owned company, and they did a terrific job at my house. We added an ADU above the garage, remodeled two bathrooms, and did other extensive work on the house. Abraham, the field manager, was responsive and available, flexible when plans needed to change to accommodate structural issues that we discover as the project progressed, and answered my endless questions. The workmen were always on time, courteous, and cleaned up the site every day before they left. Probably the easiest way to find out if HIC can provide what you want is to call Abraham Moryossef directly (818 850 5062) and chat. I know it will be a good investment of your time. They are terrific!"
Roof & exterior paint
Working on the gas line
Artificial turf project
Roof & exterior paint
Roof & exterior paint

+53

Response time2 days
Response rate100%
6 neighbors recently requested a quote
Avatar for DT Design and Build, Inc.
DT Design and Build, Inc.
4.7(
81
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2014

Free estimates

Warranties offered

"We hired DT Design and Build for a home addition project, and we are thrilled with the results. Tal and his team were professional, knowledgeable, and a pleasure to work with from start to finish. They communicated with us regularly throughout the project, keeping us informed of progress and addressing any concerns promptly. The finished addition seamlessly integrates with our existing home, and the craftsmanship is top-notch. We would highly recommend DT Design & Build to anyone in need of a skilled, reliable contractor."
New house
New house
Bathroom
Livingroom
Bathroom

+43

Response time9 hrs
Response rate97%
Recommended by100%of homeowners
Avatar for YB Builders Group Inc.
YB Builders Group Inc.
5.0(
14
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2025

Free estimates

Credit card accepted

"Dealing with contractors is never easy, and Ben is no pushover, but with very few exceptions, Ben and his crew do what they say they are going to do when they say they are going to do it, and they do it very well. What else can you really ask for from contractors. He's organized and a person of integrity. I liked that he sent a Google chart with supplies to purchase that we could work together that helped me figure out what kind of parts and tiles to purchase. Great experience and our bathrooms are amazing."
Bathroom Remodel
Master bathroom
Master bathroom
Master bedroom
Kitchen Remodel

+74

44 neighbors recently requested a quote
Avatar for Trig Builders, Inc.
Trig Builders, Inc.
4.9(
37
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2004

Free estimates

Warranties offered

"We hired Trig Builders to tear out our bathtub, shower and shower walls and to build a tub deck with a drop in tub; install marble tiles on the shower floor & walls and vanity backsplash, remove and relocate the old recessed lights and vent fan and install the shower/bath all plumbing fixtures. Like most other people, we also had many other bids before deciding who to hire for that work and at the end of this hard process, we decided to go ahead with Trig Builders. Our decision to hire and work with them was based on their positive online opinions from other clients and the excellent reputation that they have. At first, we worked only with Michelle about the design and the selection of materials of the project. It was a pretty easy and not complicated to work with her. At the end of that process, we were extremely happy with the overall design and the flow of the space. After that stage, Yossi was assigned to our project and he took over with the designs and flow. During the work, we had close to 6 workers that worked daily on the entire project starting with demolition, framing, and construction, paint and finishes installation. By having all this people working at the same time, we felt and noticed that the work is running super-fast and we loved it! Yossi made sure that each stage will be approved by him and this was the main reason why he visited our house on a daily basis (sometimes even more than once a day). The work was completed after 3 weeks from the day that Michelle met with us and we approved the design and the flow. At the end of the work, Yossi and Michelle came over to the final meeting where we inspected all the work and the final project. During that meeting, we informed them about few issues and Yossi was able to take care of them the following day making sure that they all will be resolved and approved by us. This is the greatest service we could think of. Trig Builders did a great work and we do recommend them for any construction work."
Addition in Diamond Bar
Addition in Diamond Bar
Addition in Diamond Bar
Addition in Diamond Bar
Addition in Diamond Bar

+15

Response time7 hrs
Recommended by87%of homeowners
Avatar for Green Planet Remodeling
Green Planet Remodeling
5.0(
73
)
Addition to Existing Structure - Build

Serving Westchester, CA and surrounding areas

Approved

In business since 2013

Free estimates

Customers say: Quick response

"I hired Green Planet Remodeling for a room addition. I also received quotes from some other companies but offer from Green Planet Remodeling was most acceptable. The project went perfect, my project manager was very professional and informative, I always knew what was going on. They finished within promised time and was completely honest about everything else. The quality of their job is top notch. Thanks, will recommend to others!!"
Bathroom Remodeling
Bathroom Remodeling
Kitchen Remodeling
Kitchen Remodeling
Kitchen Remodeling

+35

Response time1 day
Response rate95%
Recommended by100%of homeowners
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FAQs for addition to existing structure building service projects in Westchester, CA

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 Westchester, 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.