ADU Construction in Cornwall, Ontario
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What is an ADU (Accessory Dwelling Unit)?
An ADU, or Accessory Dwelling Unit, is a small, separate home on the same lot as a main house. It has its own entrance, living area, kitchen or kitchenette, and bathroom so that someone can live there independently. People often use ADUs for family members, guests, or as rental units.
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Common types of ADUs include:
Built as an addition that shares at least one wall with the main house. It connects to the home but still functions as its own private unit.
A separate small house in the yard, similar to a tiny home or garden cottage.
An existing garage turned into a living space. This reuses the structure and is usually much faster than building a new unit.
A living unit built over a garage. It keeps the footprint small while still adding a complete mini apartment upstairs.
A finished basement with its own entrance, bathroom, and kitchen area. A good fit for homes with decent ceiling height and windows. This is the most common ADU and is typically the easiest one to complete from a permit and planning perspective.
Services
ADU Services in Cornwall, Ontario
We provide complete ADU construction in Cornwall, handling everything from the initial consultation through the final touch-ups. It begins with a meeting where we learn your goals, review the property, and talk through basic design options. This visit usually lasts about an hour, sometimes a bit longer.
Next is the design and blueprint phase, where we prepare custom plans and permit drawings. This stage often takes 1 to 3 months, depending on the project and your design choices. This phase also goes into much more detail than just the drawings. We help select materials, finishes, fixtures, etc. After that, our ADU builders handle the entire construction of your ADU.
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Our ADU Construction Process – From Concept to Completion
Our ADU construction process starts with a simple first contact. You can call us or fill out an online form, and our Office Administrator will reach out for a short, friendly intake call. They ask a few key questions, then pass a clear summary to our Founder, so the in-person visit has a starting point.
Next is the on-site consultation and site review. Our Founder meets you at your property, walks the yard or garage with you, talks through size, access, parking, budget, and local rules, and helps you see what kind of ADU makes sense for your lot. A paid Design Contract always follows this step. No matter the size, materials, etc, this is a very important step.
Then we move into detailed design. We create the layout, exterior look, windows, and interior finishes (with your feedback!), including kitchen and bathroom details. Once you approve the design, we prepare a clear construction schedule that explains the main stages of excavation, foundation, framing, utilities, and finishing work so you know what will happen and in what order.
Most clients stay in their primary home while the ADU is being built, since the work is usually done in the yard or above the garage. We let you know in advance of any short interruptions to power, water, or driveway access. During construction, we offer regular walkthroughs so you can see progress and ask questions. When the ADU is complete, the work is covered by a three-year warranty, and we only call the project done when you are happy with your new space.
Millennial Contracting has partnered with 
Home renovations can come when you least expect them.
As a family, we understand that you can’t always afford to pay for large expenses to your home when you need them the most.
Financing may be a better option for your next home renovation.
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Why Choose Millennial Contracting for ADU Construction
Building an ADU on your property is a big step, so you want ADU builders that can truly handle it. At Millennial Contracting, we handle everything as a single, organized process: design, permits, and construction. As a trusted ADU contractor, we follow Ontario building codes and keep you updated so you always know what is happening on your lot.
Homeowners already trust us for home remodeling in Cornwall, ON, a new home addition, and as their preferred garage conversion contractor, sunroom contractor, and condo renovation contractor. If you are curious about adding an ADU to your property, get in touch, and we will discuss options, budget, and next steps. To make everything worry-free, you need a reliable ADU construction company.
FAQ
Frequently Asked Questions
What is ADU in construction?
How to find a good ADU contractor?
What is the most cost effective way to build an ADU?
The most cost-effective adu construction approach often depends on your existing property. Common budget-friendly options include:
Converting a garage or basement instead of building from scratch
Using a simple, efficient floor plan
Working with experienced adu home builders who can optimize materials and labor
Planning utilities carefully to reduce infrastructure costs
Partnering with a knowledgeable adu contractor can help avoid costly mistakes and maximize long-term value.
How much value can an ADU add?
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