How Can I Tell If My Home Has Poor Ventilation?

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Common signs of poor ventilation

Ventilation problems rarely show up as one dramatic symptom. Instead, they tend to appear gradually as a combination of moisture, odour, and comfort issues. Watch for these patterns:

• Condensation or fogging on the inside of windows, especially in the morning
• A musty or stale smell that lingers in bathrooms, closets, or basements
• Visible mold or mildew around window frames, in bathrooms, or on exterior walls
• Rooms that feel stuffy, stale, or 'heavy' even when the thermostat is set correctly
• Excess humidity that makes the home feel clammy in summer or overly damp in winter
• Cooking or bathroom odours that hang around long after you've finished cooking or showering
• Static electricity or unusually dry air in winter (a sign air isn't cycling and being balanced properly)

Why this happens

Many homes in Metro Vancouver, particularly newer or recently renovated ones, are built tighter than older housing stock to improve energy efficiency. That's good for heating and cooling costs, but it also means less natural air leakage through gaps and cracks. Without a dedicated way to bring in fresh air and exhaust stale, moist air, humidity and pollutants can build up indoors. Bathroom and kitchen exhaust fans that are undersized, blocked, or rarely used make this worse, as does a lack of any whole-home fresh-air system.

Older, leakier homes have the opposite issue less often, but poor ventilation can still show up in specific rooms, like a basement or an addition, that don't get enough airflow from the rest of the house. Renovations that add insulation and new windows without also addressing ventilation are a common trigger point, since the home suddenly holds moisture and odours that used to escape through small gaps and drafts.

What to check yourself

• Run bathroom and kitchen exhaust fans during and after showers or cooking, and confirm they're actually venting outside (not just into an attic)
• Check that furniture, boxes, or curtains aren't blocking supply or return air vents
• Look for condensation buildup on windows over a few mornings, particularly in winter
• Note any rooms that consistently feel stuffier or more humid than the rest of the house
• Check if your home has a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) already installed, and whether the filter has been cleaned recently

If your home was built or majorly renovated in the last couple of decades, it may already have an HRV or ERV system. These are worth locating, since a neglected or improperly balanced unit can cause the very symptoms of poor ventilation it's meant to prevent.

When to call a professional

If you're seeing recurring condensation, mold, or musty odours after checking the basics above, it's worth having a technician assess your home's ventilation rather than guessing. This is especially true if your home is tightly sealed and has no mechanical fresh-air system at all. A technician can check exhaust fan performance, inspect or commission an HRV/ERV, and recommend whether adding or upgrading ventilation makes sense for your home's size and layout. CANRO Heating & Cooling serves homes across Metro Vancouver and can walk through your options, including how HRV/ERV installation costs may qualify for CleanBC or FortisBC rebate programs.

Frequently asked questions

Reviewed by the CANRO Heating & Cooling service team — July 07, 2026. Technical Safety BC gas licence LGA0043870 · boiler licence LBP0046450 · Red Seal certified · WorkSafeBC and liability insured · 4.9★ from 85+ Google reviews · serving Metro Vancouver since 1999 · (604) 359-1081.