5 Common Mistakes People Make When Building a Legal Basement in Ottawa

Finishing a basement is a smart investment—but doing it legally in Ottawa comes with strict rules. We've seen too many homeowners and investors spend thousands only to fail inspection because of simple, avoidable mistakes.

At R&G Walls, we specialize in building and finishing legal basement suites that pass code and get rented fast. Here are the top 5 mistakes we see—and how to avoid them.

❌ Mistake #1: Skipping Permits

Why it’s a problem:

No permit = no legal suite = no income potential. You also risk fines, stop work orders, or being forced to rip out finished work.

✅ What to do instead:

Apply for a building permit through the City of Ottawa’s Secondary Dwelling Unit program. We can work with your designer or refer you to one if needed.

❌ Mistake #2: Using Standard Drywall Where Fire-Rated Is Required

Why it’s a problem:

Code requires Type X (5/8") fire-rated drywall between units to meet fire separation standards. Using 1/2" standard board will cause you to fail inspection.

✅ What to do instead:

At R&G Walls, we install fire-rated drywall with proper fasteners, mudding, and fire caulking to meet Ontario Building Code (OBC) specs.

❌ Mistake #3: Not Meeting Egress Requirements

Why it’s a problem:

Each bedroom in a legal basement unit must have a window large enough to climb out of in case of emergency—called egress. If it’s too small or not properly framed, the unit won’t pass.

✅ What to do instead:

Ensure all windows meet minimum opening dimensions for height, width, and clearance. We can frame new window openings or adjust rough-ins to match.

❌ Mistake #4: Forgetting Soundproofing

Why it’s a problem:

Legal units require sound transmission control (STC) between floors and shared walls. If you don’t install resilient channel, insulation, or special drywall assemblies, it can lead to complaints—or code issues.

✅ What to do instead:

We use resilient channel + insulation or QuietRock® boards to meet soundproofing requirements without making ceilings too low.

❌ Mistake #5: Hiring the Wrong Contractor

Why it’s a problem:

Many contractors don’t know legal basement requirements. They’ll drywall with the wrong materials, skip fire caulking, or ignore moisture management—and leave you with failed inspections and costly rework.

✅ What to do instead:

Hire a pro who understands legal basement drywall requirements. At R&G Walls, we’ve done dozens of these projects across Ottawa, and we’re happy to help you plan it right.

🛠️ Bonus Tip: Plan Electrical & Plumbing Before You Drywall

Once drywall is up, it's expensive to open it up again. Always finalize:

• Pot light layouts

• Duct and venting

• Plumbing for bathrooms/kitchens

• Smoke/CO detectors and interconnects

We coordinate with your other trades to make sure everything is code-compliant before we close up the walls.

🏆 Trust Ottawa’s Legal Basement Experts

At R&G Walls, we help homeowners, flippers, and investors build legal basements the right way—with clean work, fast timelines, and inspections passed the first time.

📞 Call or text 613-869-7391 to book a free consult📍 Serving Ottawa, Barrhaven, Kanata, Orleans, Nepean & nearby towns✔ Legal basement drywall, framing, priming, painting, trim, and more