Koeppen Construction builds Accessory Dwelling Units (ADUs) in Longmont, CO, and nearby areas. Services include detached, attached, and garage conversion ADUs for rental, multigenerational living, or guest use. Permitting assistance included.

Koeppen Construction – ADU Contractor in Longmont, CO

About Koeppen Construction

Accessory Dwelling Units by Koeppen Construction

Accessory Dwelling Units (ADUs) — sometimes referred to as mother-in-law suites, backyard cottages, garage apartments, or basement apartments — are secondary living spaces built on the same property as a primary residence. They can add functional living space and contribute to the overall value of a home. Koeppen Construction offers ADU building services in Longmont, CO, and surrounding areas including Boulder, Erie, Lafayette, Louisville, Frederick, and Firestone.

Whether a homeowner is looking to accommodate aging parents, provide space for guests, or create a rental unit, Koeppen Construction brings experience in planning and building accessory dwelling units to suit a range of needs. As an established ADU contractor in the Longmont area, they work with homeowners from the early planning stages through to project completion.

Planning and Design

Koeppen Construction places emphasis on interior planning and efficient design. Their approach focuses on helping homeowners think through the layout and functionality of a space before construction begins. This includes considering foot traffic flow, space efficiency, and how the unit will integrate with the existing property.

They work on various types of ADU projects, including:

  1. Detached ADUs — standalone backyard cottages or separate structures on the property
  2. Attached ADUs — units connected to the main home, such as basement apartments
  3. Garage conversions — converting existing garage space into a livable unit

Each project type comes with its own set of design considerations. Koeppen Construction works to ensure that the design is practical and compliant with local zoning regulations before any work begins.

In Longmont, CO, ADUs are permitted, but local zoning ordinances and building codes apply. Homeowners are required to obtain the appropriate permits before construction starts. Koeppen Construction can assist clients in navigating the permitting process and understanding what is required by the city's planning department.

Experienced Contractors Serving the Longmont Area

Koeppen Construction employs certified contractors with experience in ADU projects. Their team is familiar with the requirements and challenges that come with building accessory dwelling units, whether that involves new construction or converting an existing structure like a garage or basement.

Converting an existing structure into an ADU can often be a more cost-effective option compared to building from scratch. Koeppen Construction evaluates the existing conditions and works with homeowners to determine the most practical path forward.

Common uses for ADUs that Koeppen Construction builds include:

  1. Rental income units
  2. Multigenerational living arrangements
  3. Guest accommodations
  4. Home office space

ADUs can also positively affect property value by increasing the functional use of a lot and meeting diverse housing needs. For homeowners in Longmont and the surrounding Colorado communities, an ADU can be a practical addition to their property.

Koeppen Construction serves Longmont, Boulder, Erie, Lafayette, Louisville, Frederick, Firestone, and surrounding areas in Colorado. Homeowners interested in building an ADU can reach out to learn more about their services and project options.

Services

Koeppen Construction performs the following services

  • Architecture & Design
  • Permit Specialist
  • Construction
  • Financing & Loans

Koeppen Construction Reviews

Nancy Ehrenreich

2026-01-21
"Im happy to write this review of work recently done by Koeppen Construction at my home. I had asked the company to convert a window in my living room into a bay window a far more complex project than Id realized. But the project details turned out just as Id wanted them to be, the woodwork was excellent confirmed to me by friends who know more than I do about such things, and the project ran no more than a reasonable amount of time past schedule especially given that we were doing it in the winter. Graham Koeppen and his crew were very patient with my frequent questions I found it fascinating to watch the project take form, and I couldnt be happier with the result. Thanks, Graham, Joe, Dexter and all!"

Brian Cox

2025-07-17
"Koeppen construction did a remodel of our basement and partial remodel of our kitchen. We were extremely impressed with the level of professionalism and knowledge, the quality of contractors and subtractors and especially their integrity, transparency and communication. Graham's team from the office staff to the site supervisor and carpenter's are excellent at their jobs and genuinely care about clear communication, attention to detail and problem-solving. Graham and Joe did an excellent job of listening to what we wanted but also provided intelligent, practical suggestions that were extremely valuable. Because Koeppen has worked for a long time in this community they have developed excellent resources for subcontracting or finding suppliers at competitive prices and understand how to navigate through the permitting process. In my experiences, all construction projects will encounter unexpected obstacles - the reason to hire qualified professionals is that they can successfully problem-solve and adapt or figure out work arounds. Koeppen handled every issue that arose and stood by their work. Highly recommend. Brian Cox"

Jennifer Fick

2024-10-28
"I highly recommend Koeppen Construction! We did a complete remodel of the entire first floor of our home and are very pleased with the results. Graham and his team were very responsive and have excellent attention to detail. We will definitely use them again when we are ready to remodel our second floor."

Melissa Swan

2024-10-16
"We could not be happier with our basement! From start to finish we felt confident our vision was going to be made into a reality. During the build the team offered suggestions for a more professional finish that we hadnt thought of, even if it meant more work for them. With any type of construction, obstacles will pop up. This team took the time to discuss and find a resolution that matched the quality of the rest of the project instead of just throwing together the easiest fix. I am very thorough person when paying attention to details. It was communicated in the beginning the extreme importance I was placing on a cohesive aesthetic. I wanted to match construction in a space 18 years after original construction. I did not want my project to look like an afterthought. GJKoppen absolutely accomplished that -which was not an easy feat! A great amount of time and effort was made in researching fixtures and finishes as well as tracking down obscure items that had been discontinued. We receive raving compliments on the workmanship from anyone who sees the space. This team genuinely cares about making their clients happy which seems rare these days. It is obvious they take pride in their work and it shows in the final product. They are all gems and we could not have made a better choice."

Brenda and Bob Taylor

2024-10-09
"We just finished a major kitchen remodel with Koeppen Construction. Our dark, small, dated 1970s kitchen was transformed into a bright, beautiful and open kitchen. The remodel also included surrounding areas - a bathroom, a laundry area and a front room. Graham Koeppen created a wonderful design for our space. He thought of things we would never have thought of and as a result, we have a kitchen that I am excited to cook in and to share with family and friends. We were very impressed with all of the workers who worked on this project! They were all very skilled, punctual, respectful and cleaned up every day! Even the subcontractors that Koeppen used were great to work with. We also appreciated the communication throughout the whole process. Our project manager, Joe, was great! Many times he stayed later or came in extra to work on something that needed attention. He always took care of any concerns I had! And Niki was truly awesome! She always followed up with me or whoever was needed to remedy any issue at hand. She was quick to address my concerns and to answer my "silly" questions! I appreciate her "holding my hand" throughout this whole process, as I had never been through a remodel before! We will continue to recommend Koeppen Construction to our friends. Thank you to all who had a part in creating our dream kitchen. It far exceeded our expectations! Brenda and Bob Taylor"

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Specifics

Licensed Turnkey Solutions

Opening hours

Monday 9:00AM - 5:00PM
Tuesday 9:00AM - 5:00PM
Wednesday 9:00AM - 5:00PM
Thursday 9:00AM - 5:00PM
Friday 9:00AM - 5:00PM
Saturday -
Sunday -

Location

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