Should I Build an ADU? The Pros and Cons Of Additional Units
Additional units can give homeowners independent living space for family members or tenants while making better use of a property they already own. An ADU may be a good choice if you need a separate living space and your property, budget, and local requirements can support it. If you simply need more room, a basement renovation or traditional home addition may be a better fit.
At BREHN Home Solutions, we often recommend starting with a simple question: what does your home actually need? An ADU might be the answer, but it isn’t the only way to create more functional living space.
For homeowners in Fergus, Elora, Guelph, Centre Wellington, and surrounding communities, weighing the benefits and practical considerations can help determine which renovation makes the most sense.
If you’re still learning about ADUs and how they work, start with our guide “What is an ADU: Your Guide to Accessory Dwelling Units.”
What Are the Pros and Cons of Building an ADU?
An ADU can provide flexible, independent living space without requiring you to purchase another property. However, creating a complete residential unit can also involve a significant renovation, municipal requirements, and ongoing maintenance.
Here is the quick version:
Potential benefits of an ADU include:
More usable living space
Privacy for family members
Multigenerational living options
Potential rental income
Flexibility as your household changes
The ability to stay in a home and neighbourhood you love
Things to consider before building an ADU include:
Upfront renovation or construction costs
Municipal and permitting requirements
The physical limitations of your property
Additional maintenance
The responsibilities that come with renting the unit
Whether you actually need a fully independent residential space
What Are the Biggest Benefits of Building an ADU?
1. More Living Space Without Moving
Many homeowners discover they don’t actually want to move. They just need their home to work differently.
You may need more room because an aging parent is moving in, an adult child is staying home longer, or your family wants additional space and privacy. If you love your home, yard, neighbourhood, or community, creating an ADU can be an alternative to searching for another property.
Depending on your existing home and lot, that space could come from a basement conversion, attached addition, garage, or another type of additional dwelling.
If expanding your home’s footprint makes the most sense, our Home Additions in Fergus page explains more about the types of additions we build.
2. Flexible Space for Family
One of the most useful applications for an ADU is multigenerational living.
An aging parent or other relative can remain nearby without requiring everyone to share the same kitchen, bathroom, and living areas. An ADU can also give adult children more independence while allowing them to remain on the family property.
That separation can make a significant difference. Living close to family is not the same as sharing every part of a home with them.
If you’re planning the space for an aging family member, accessibility can also be considered from the beginning. Entrances, bathrooms, doorways, stairs, and everyday mobility can all influence how well the space works over the long term. A separate kitchen, bathroom, living area, and entrance can also give family members significantly more privacy and independence.
3. Potential Rental Income
For some homeowners, rental potential is another reason to consider additional units. A legal additional residential unit may provide an opportunity to rent part of your property while maintaining a separate primary living space.
If renting is one of your goals, we recommend making that clear early in the planning process. A unit intended for tenants needs to be designed with applicable municipal, building, fire, and safety requirements in mind.
What Should You Consider Before Building an ADU?
ADUs offer plenty of benefits, but they also require more planning than many other renovations.
These considerations aren’t necessarily reasons not to build an ADU. They can help determine whether it’s the best way to accomplish your goals or whether another renovation would be a better fit.
How Much Will the Project Involve?
Creating an independent residential unit usually requires more than cosmetic renovation work. Depending on the project, the scope could include:
A kitchen and bathroom
New or relocated plumbing
Electrical work
Heating and ventilation
Structural changes
Windows and appropriate exits
A separate entrance
Fire and sound separation
Permits and inspections
The amount of work depends heavily on what already exists.
Converting a suitable basement, for example, can be a very different project from constructing a new detached unit. If your main goal is simply to gain another bedroom, office, or family room, you may discover that a different renovation gives you what you need without creating a complete second residence.
Does Your Property Suit the Type of ADU You Want?
One of the biggest mistakes we see is deciding on a specific type of renovation before looking closely at the property.
You might picture a detached ADU in the backyard only to discover that an attached unit makes more sense. You may also assume you need to build new space when your existing basement offers a better opportunity.
Your home’s layout, existing services, lot, access, zoning, and other site conditions can all influence the options worth exploring.
Working with an experienced renovation contractor can help you look at the goal first and determine which renovation makes sense for the property.
What Does Your Municipality Allow?
Municipal and building requirements need to be part of the conversation from the beginning.
Homeowners in Fergus and Elora should confirm the current requirements that apply through the Township of Centre Wellington, while homeowners in Guelph should review the City of Guelph requirements for additional residential dwelling units.
Ontario homeowners can also consult current provincial regulations related to additional residential units.
Are You Prepared for the Additional Maintenance?
More living space also means more space to maintain.
A second kitchen, bathroom, heating system, exterior area, or separate structure may add to the ongoing upkeep of your property. If you rent the unit, being a landlord also comes with responsibilities beyond maintaining your own household.
That doesn’t mean an ADU isn’t worthwhile. It simply needs to be part of the long-term plan.
How Do I Know if an ADU Is Right for My Property?
Start with the problem you want the renovation to solve rather than deciding on the renovation first.
Ask yourself:
Who will use the new space?
Do they need a fully independent living area?
How much privacy do they need?
Will the space be rented eventually?
Could your existing basement provide the space?
What budget are you prepared to invest?
What does your municipality allow on your property?
If you need a genuinely independent space that can remain useful as your household changes, an ADU may be a perfect fit.
If the real problem is simply that your current home needs more usable space, another renovation may accomplish the same goal with less complexity.
Is a Basement Apartment a Better Option?
For some properties, yes.
If your basement has the space and physical characteristics needed for a legal apartment, working within your existing footprint may make more sense than constructing a new addition or detached structure.
BREHN’s Project Tait is a good example. We transformed an existing basement into a legal apartment with a private entrance, second bedroom, upgraded laundry room, and full second kitchen. The project created independent living space without requiring a separate building.
If this sounds closer to what you need, our guide to building a legal basement apartment in Ontario explains some of the considerations involved.
We would rather help a homeowner find the renovation that makes sense for their property than recommend a larger project simply because it is bigger.
Would a Traditional Home Addition Make More Sense?
An ADU and a traditional home addition solve different problems.
If you need independent living space for another household, an ADU may be worth exploring. If your existing household simply needs more room, you may be better served by an addition that becomes part of the main home.
A traditional addition could create another bedroom, a larger kitchen, a family room, home office, primary suite, or additional storage without creating a separate residential unit.
You still gain valuable square footage, but you aren’t necessarily creating a separate residential unit with its own kitchen, bathroom, and other requirements.
Our guide to planning a home addition in Centre Wellington is a good starting point if you’re comparing these options.
Are Additional Units Worth It?
For the right property and household, additional units can add a significant amount of flexibility to a home.
They can create independent space for family members or tenants, offer greater privacy, and allow homeowners to adapt a property instead of moving. However, cost, maintenance, municipal requirements, and the physical limitations of your property all need to be considered.
The better question isn't simply “ADU or no ADU?” It's what renovation will make your home work best for you? The better question is: what renovation will make your home work best for you?
Ready to Find the Right Renovation for Your Home?
If you’re considering additional units for a property in Fergus, Elora, Guelph, Centre Wellington, or a surrounding community, we can help you explore your options.
At BREHN Home Solutions, we work on accessory apartments, additional dwellings, basement renovations, garages, home additions, and smaller renovation projects. We can look at your existing property, talk through what you need from the space, and help determine which approach makes sense.
Contact BREHN Home Solutions to tell us what you have in mind!
