70 Canadian cities · prices and programs checked October 8, 2026

Home health check

Four quick checks for a healthier house: what a radon test result means, the winter humidity that keeps your windows dry, how many smoke and carbon monoxide alarms your province requires and recommends, and when mould needs a professional.

Home health check for Toronto

Set up for Toronto, Ontario, as an example. Pick your city above to load its own winter temperatures, radon survey results and alarm rules.

Four quick checks, set up with Toronto's winter temperatures and Ontario's alarm rules. Change any value; nothing you enter leaves your browser.

Radon test result

Long-term result

Unit

Pre-filled with the 2024 Cross-Canada survey's average (geometric mean) for Toronto. Replace it with your own result from a test of at least 3 months.

40Bq/m³ (1.1 pCi/L)

Scale to 800 Bq/m³. 1 pCi/L = 37 Bq/m³.

Below the guideline of 200 Bq/m³. No action is required. Health Canada still advises keeping radon as low as reasonably achievable, and retesting after major renovations or changes to the basement.

Health Canada's lifetime lung cancer risk: for a never-smoker about 1% at low radon, 2% after lifetime exposure at 200 Bq/m³ and 5% at 800; for a smoker 12%, 17% and 30%. Only a test of 3 months or longer gives an annual average; short tests can mislead.

Winter humidity and window condensation

Indoor temperature°C

Indoor humidity%

Windows

Outdoor temperature

January average (−3.7 °C) Cold snap (−16.3 °C) Other

January average: ECCC 1981–2010 normals. Cold snap: NRCan's HOT2000 winter design temperature for Toronto.

58%highest humidity before the glass fogs at −3.7 °C

Double glazing, clear (1970s–1990s) (U 2.86): condensation starts at about −20.1 °C outside with 40% humidity inside.

The centre of the glass stays dry at −3.7 °C. It is about 12.5 °C, above the 6.9 °C dew point. The bottom edge and frame run colder, so condensation can start there first.

Health Canada and CMHC: keep indoor humidity between 30% and 50%. Below −10 °C outside, CMHC advises about 30%; Toronto averages 22 nights a year that cold.

Smoke and carbon monoxide alarms

Levels, including the basement

Levels with bedrooms

Bedrooms

Separate sleeping areas

A sleeping area is a group of bedrooms off one hallway.

Furnace, water heater, fireplace or stove that burns fuel Attached garage

Smoke alarms required by law: 3
Smoke alarms for full coverage (new-home standard): 6
CO alarms recommended: 2

Required: at least 3 under Ontario rules.

“Full coverage” follows the National Building Code for new homes: one on every storey including the basement, one in each bedroom and one outside each sleeping area, interconnected. CO: NRCan advises one near the furnace or other fuel-burning appliance and one in each bedroom area.

Mould: clean it yourself or call a pro?

Number of patches

Largest patch

Example values shown. 1 m² is about 10.8 sq ft.

Small: you can clean it yourself if you are healthy.

Up to three patches, each under 1 m²: clean with water and unscented dish detergent, wearing safety glasses, an N95 mask and rubber gloves (CMHC). People at risk from mould should not clean it.

Fix the moisture source first. Testing for mould types is usually unnecessary (Health Canada). You entered 2 patches, the largest about 0.5 m².

How we calculate this

Radon

1 pCi/L = 37 Bq/m³ (Health Canada). The Canadian guideline is 200 Bq/m³; above it Health Canada recommends fixing your home within 1 year, sooner the higher the level. Only a long-term test (at least 3 months, ideally in the heating season) tells you your annual average.

Window condensation

glass temperature = indoor − U × (indoor − outdoor) ÷ 8.33

8.33 W/m²·°C is the indoor air film from the National Building Code (RSI 0.12). The dew point comes from the Magnus formula the US National Weather Service publishes; condensation forms when the glass is colder than the dew point. These are centre-of-glass figures: the bottom edge and metal frames run colder, which is why we show CMHC's simpler rule beside them (30% indoor humidity when it is below −10 °C outside, as low as 25% in extreme cold).

Smoke and CO alarms

“Required by law” applies your province's fire code to the layout you enter. “Recommended” is the new-home standard in the National Building Code (an alarm on every storey, in every bedroom and outside sleeping areas) and NRCan's CO advice (one near the furnace or other fuel-burning appliance and one in each bedroom area). Municipal by-laws can add to provincial rules.

Well water and mould

Testing frequencies and lab fees are the ones your province publishes. Mould size categories are Health Canada's and CMHC's: up to three patches each under 1 m² can be cleaned by a healthy homeowner; more than 3 m² needs a professional.