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

Avatar for KN Remodeling & Supplies Inc
KN Remodeling & Supplies Inc
4.8(
63
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2012

Free estimates

Warranties offered

"The KN Remodeling team did an excellent job at our home completely remodeling 3 bathrooms, painting our entire home and rebuilding a huge planter outside. We trusted them in our home while we are out of town almost the entire time. We hired them back to do additional work in our home that they did quickly and expertly. The team was professional, very friendly, worked quickly, quietly, cleanly, and I would highly recommend them."
Additional Photos
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+48

Response time8 hrs
Response rate100%
4 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 Monrovia, 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%
8 neighbors recently requested a quote
RET Construction Corp
5.0(
37
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2004

Free estimates

Emergency services offered

"My wood balcony has termites and water damages. So I hired RET to do the job. Kevin gave estimates and recommended composite planks for floor and red woods for railings. His workmanship was very professional and finished on time! On top of that, Kevin updated my balcony to the latest building codes. His price is very reasonable. If you want cheap prices and lousy jobs,hire someone else! Highly recommended!"
Response time4 hrs
3 neighbors recently requested a quote
Recommended by77%of homeowners
Avatar for YB Builders Group Inc.
YB Builders Group Inc.
5.0(
14
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2025

Free estimates

Credit card accepted

"Ben helped us convert our VERY old garage (80+ years) into a modern multipurpose room. He was communicative throughout the process, friendly to work with, and the final product exceeded our expectations. We highly recommend YB Builders to anyone looking for a contractor."
Bathroom Remodel
Master bathroom
Master bathroom
Master bedroom
Kitchen Remodel

+74

41 neighbors recently requested a quote
Avatar for MF Construction & Design Inc
MF Construction & Design Inc
4.5(
82
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 1994

Free estimates

Emergency services offered

"Mike Mamen called back within the hour. Next day I showed him the problems with my 90-year-old garage's roof and wiring. He tell me that existing 2x4 rafters could be sistered rather than replaced with 2x12. Additional 2x6 tie beams across garage. He recommended all new shingles, garage door, side door, window, lights, and outlets. Exterior paint on stucco and wood trim. Mike recommended replacing the house 100A electric service panel with 200A, in addition to trenching a conduit between house and garage. He also recommended grading behind the garage to route water away from its foundation. Also, adding gutters and downspouts to both the garage and house. Later we discovered that the house's facia needed to be replaced. He drove me to two current job sites, introduced his crew, and showed the work being done. Mike is knowledgable, direct, friendly, and talkative. Listens to my concerns and ideas, then presents options and his recommendations. Responds to later questions and text messages. Knows local building codes and permitting process. Works by the book -- written contract proposals describe the job and materials. Flexible in handling changes and unexpected glitches. Does minor tasks gratis. Personally attends inspections. Likewise, foreman and electrician Luis is friendly and competent. I am pleased with the competence and results of MF Construction and Design. The entire job took about seven weeks. It was more expensive than I would have thought. OTOH I did not get other bids."
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+30

Response time2 days
2 neighbors recently requested a quote
Recommended by96%of homeowners
Avatar for Platinum Home Builders & Design, Inc.
Platinum Home Builders & Design, Inc.
5.0(
75
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2020

Free estimates

Warranties offered

"I came to know about Platinum Home Builders from a friend. We were having our first child and wanted to have a specially prepared room for her. I was very impressed with their approach. I should say that I am very satisfied with their work."
DRIP EDGE FLASHINGS
SURE NAIL TECHNOLOGY SHINGLE BY OWEN'S CORNING
TITANIUM UDL 50 UNDERLAYMENT
INSTALLATION OF NEW COOL ROOF SHINGLES
SYNTHETIC ROOFING UNDERLAYMENT

+80

Response time11 hrs
Response rate93%
Recommended by88%of homeowners
Avatar for Trig Builders, Inc.
Trig Builders, Inc.
4.9(
37
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2004

Free estimates

Warranties offered

"We needed to do a kitchen remodel for a while now so we did a massive research online and by asking friends and family in our area. After meeting with all of them and explaining to them what are we looking for, what we want to do and mainly what is our budget. We received estimates from all the contractors that we met and we selected Trig Builders because Yossi was the most competitively priced and the referrals that we got on him and his company were very positive. Yossi and the workers were very easy people to work and to deal with and Yossi designed the kitchen exactly the way we wanted it with some nice additions of things that we didn’t think we will get. His suggestions about the new kitchen layout, where and what materials to buy were very helpful. Also, his advises and recommendation on where to buy the cabinets, lightings, plumbing and appliances saved us a lot of money. The end result of the new kitchen was perfect and one of the things that added a huge plus before we hired them was the warranty that included in the price of the work that they did."
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 Skyline Konstruction
Skyline Konstruction
4.9(
11
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

In business since 2016

Free estimates

Warranties offered

"Skyline construction did an excellent job. Juan Munoz was a great contractor. We wanted to build an ADU but didn’t know who to trust. The workers were neat and careful. Every worker treated us with respect and we’re very friendly. I would highly recommend them to any of my friends or family."
Restroom
Home remodel
Laundry
Home remodel
Laundry

+93

Response time2 days
Response rate100%
8 neighbors recently requested a quote
Avatar for Imperial Remodeling Inc
Imperial Remodeling Inc
4.6(
128
)
Addition to Existing Structure - Build

Serving Monrovia, CA and surrounding areas

Approved

Super Service Award Winner

In business since 2006

Free estimates

Emergency services offered

"Fantastic. Not only is the end result superb but the process was as smooth and efficient as it could possibly have been. Gino consults you on everything, even after you’ve made the initial choice of cabinets, tile, countertop, scope of work, etc. He talks to you every day to update you. He has people working continuously, all organized so that no time is wasted. Once he started there was not a (week)day when his people weren’t working on my job, usually all day long. He has the work and teams organized and timed so that each one comes to your project as few days as possible, which reduces the cost. Gino is a stickler for detail, and getting everything exactly right, aesthetically and functionally, and the people he hires are very highly skilled with the same attitude. They’re also very clean. They sealed off the kitchen during the demolition so that the dust wouldn’t get to the rest of my open-plan condo. In construction they minimized particulate matter by doing all of the heavy cutting off-site. And they vacuumed the space every day before leaving! I’ve had contractors in several different cities and states and none came even close to this level of work, but it’s how remodeling should be! The price of my project was reasonable given the very high quality of the work, and the scope of work. Gino is very straight with you. The only costs that exceeded the estimate were due to my decisions to upgrade materials, or add a job to the project, and discovery of conditions in the existing structure that had to be upgraded (e.g., electrical). I’ve never been able to recommended a contractor before -- all the ones I’ve had have been so bad -- but I recommend Imperial Remodeling with two thumbs up."
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+185

Response time1 day
Recommended by89%of homeowners
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FAQs for addition to existing structure building service projects in Monrovia, 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 Monrovia, 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.