What is an ADU or ARU? Everything Homeowners in Elora, Fergus, Guelph & KW Need to Know
- LUMA Build Design
- Nov 6
- 4 min read
Updated: Nov 15
As housing needs evolve across Ontario, more homeowners are turning to Additional Dwelling Units (ADUs) and Additional Residential Units (ARUs) to expand their living space, generate rental income, or create flexible multi-generational homes. At LUMA Build Design, we specialize in helping clients across Elora, Fergus, Guelph, Elmira, Kitchener, Waterloo, Drayton, and Arthur bring these smart, efficient spaces to life.
In this post, we’ll cover:
What is an ADU/ARU?
Why build an ADU or ARU?
Types of ADUs/ARUs
Zoning and regulatory considerations in our region
Challenges (and how we solve them)
Case studies from real LUMA projects
Property suitability & checklist
Cost & return on investment
What is an ADU or ARU?
An Additional Dwelling Unit (ADU) or Additional Residential Unit (ARU) is a self-contained living space with its own kitchen, bathroom, and entrance, located on the same property as a primary home. These can be basement apartments, garage conversions, coach houses, or separate backyard units.
They are known by several names — in-law suite, secondary suite, granny flat — but all fall under the umbrella of ADUs or ARUs, depending on municipal terminology. In Ontario, recent legislation has made it easier for homeowners to build them.
Why Build an ADU or ARU?
We’re strong advocates of ADUs and ARUs. They’re a fantastic option for families that:
Need more space for adult children or elderly parents
Want to create multi-generational properties
Are looking for income through long-term or short-term rentals
Want to increase their property’s value and market appeal
In fact, many homeowners are doubling their home’s footprint without needing to move. Even a well-finished basement ARU can dramatically increase livability and resale value.
Types of ADUs & ARUs
At LUMA, we design and build:
Basement Suites – fully independent units below grade
Coach Houses – detached homes in a backyard or above a garage
Garage Conversions – turning unused garages into modern suites
Attached Units – additions or side-units to existing homes
Unit sizes typically range from 1,000–1,700 sq ft for basement ADUs to 2,500+ sq ft for detached coach houses.
Zoning & Regulatory Factors in Ontario
Municipalities like Elora, Fergus, Guelph, Elmira, Kitchener, and Waterloo have unique zoning rules for ADUs/ARUs, including:
Lot size and setbacks
Maximum unit size
Septic system capacity (if applicable)
Parking requirements
We work closely with local building departments to ensure every design meets zoning by-laws and Ontario Building Code standards. You don’t have to worry — we handle zoning research, permit drawings, and applications on your behalf.
Common Challenges (And How LUMA Solves Them)
Some homeowners believe they can’t build an ADU/ARU because:
Their lot is too small or irregular
They’re on septic
It will hurt their property value
We’ve overcome all of these challenges. Our team has creatively designed ADUs in tight, awkward lots, and handled septic upgrades or assessments where needed. In reality, adding square footage increases property value — especially when the space is well designed and legal.
Case Study: Coach House ADU in Fergus
We built this beautiful ADU loft. It includes a modern kitchen, private entrance, and full bathroom — dramatically increasing the home’s functionality and resale appeal.
Design & Comfort Features
We love making ADUs and ARUs feel like home. Some of our favourite features include:
Mini-split heat pump systems for year-round comfort
Soundproofing and resilient channels between floors
Creative designs that make each LUMA unit feel like a mini custom home
Whether attached or detached, we ensure each space feels bright, modern, and tailored to your needs.
Is My Property Suitable for an ADU or ARU?
Here are a few factors we look at:
Lot size and shape
Distance from property lines
Zoning allowances for ARUs
Septic system capacity (if rural)
Parking and access options
We also keep up with all Ontario building code changes, so you don’t have to. Our team includes designers and permit specialists who ensure every unit meets code — and has that unmistakable LUMA quality.
How We Build Your ADU/ARU – Our Process
We take care of everything:
Property Assessment – zoning, lot, septic, setbacks
Custom Design – tailored to your goals and budget
Permit Drawings & Applications
Construction – managed from start to finish by LUMA
Final Touches & Move-In
Your only job? Tell us your vision — we’ll handle the rest.
Cost & ROI
Every project is different, but our clients typically see a 70%+ return on investment when adding a legal ADU or ARU. Whether you rent it or use it for family, it’s a smart way to grow your property’s value and usability.
Common Questions Homeowners Ask
What is an ADU?
An Additional Dwelling Unit (ADU) is a second self-contained home on the same property as a primary residence.
What does ADU stand for?
ADU = Additional Dwelling Unit. In Ontario, ARU (Additional Residential Unit) is also used.
Why build an ADU?
To create more living space, support multi-generational families, or generate rental income.
Types of ADUs?
Basement suites, coach houses, garage conversions, and detached backyard homes.
Can I build an ADU on my property?
Very likely! Let us assess your lot and zoning — we’ll find out what’s possible and guide you through it.
Ready to Explore an ADU or ARU on Your Property?
If you're in Elora, Fergus, Guelph, Elmira, Kitchener, Waterloo, Drayton, or Arthur, we’d love to help.
Reach out today to book your consultation with the LUMA Build Design team — and start creating more space for what matters most.
Links to ADU information in Centre Wellington and Surrounding
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