Case Study: How We Turned an In-Law Suite into a Safe, Legal Secondary Suite

Transforming an old in-law suite into a fully legal secondary suite isn’t just about meeting code, it’s about creating a safe, comfortable space that truly works for modern living. Our team recently completed a design project in Kingston, Ontario, that perfectly shows how smart design and attention to detail can transform a home while keeping safety front and center.  

When we first walked through the space, it already had great bones and even a convenient walkdown entrance, an important asset for a legal suite. But to bring it up to code and get it officially recognized, several key updates were needed.  

Step one: Light, air, and safety  
One of the biggest upgrades was adding a proper egress window and adding natural light and ventilation into the living room. This simple change did double duty, it not only provided the legally required emergency exit but also brought in more natural light and ventilation. That alone made the space feel brighter and more open right away.  

(Images Courtesy of She Shoots Inc.)

Step two: Fire separations that save lives  
Next came the real lifesavers: fire separations and safety systems. We installed fire-rated doors, enclosed the mechanical room, incorporated duct type smoke detectors that turn off fuel and electrical supply when triggered and added proper smoke detectors in key locations. These upgrades aren’t just boxes to check, they provide crucial fire protection and peace of mind for everyone living in the home. Creating clear fire separations between the main floor and the suite means each unit is safer and more secure.  

(Images Courtesy of She Shoots Inc.)

Step three: Better layout, better living  
While code requirements drove some of the design changes, we also took the opportunity to improve how the space functions day to day. We removed the old interior stairs between the units, which let us add a laundry area for the main floor and free up more living space below. Then we reconfigured the kitchen layout to improve flow and make the suite feel more spacious and efficient.  

(Images Courtesy of She Shoots Inc.)

The end result  
The finished secondary suite is legal, comfortable, and built to modern safety standards. It’s brighter, safer, and more functional than ever, an example of how the right design decisions can bring an older property into compliance while improving how people live in it.  

At the heart of it all are fire separations, proper egress, and reliable detection systems, features that don’t just meet the law but genuinely protect lives.  

If you’ve been thinking about legalizing your in-law suite or adding a secondary unit to your home, House of Three can help guide you through every step of the design.  Get in touch with our team today to see how we can turn your existing space into a safe, legal secondary suite you’ll be proud of.