What pipes are most likely to freeze?

Pipes in unheated areas like crawl spaces, basements, and exterior walls are most vulnerable to freezing, especially those made of copper or PEX that carry water rather than drain waste.

Location is the biggest factor in pipe freezing risk. Pipes running through uninsulated crawl spaces, unheated basements, or within exterior walls face the greatest danger. Kitchen and bathroom pipes on outside walls are particularly vulnerable, especially if there's inadequate insulation behind them. Pipes in attached garages, near foundation walls, or in areas where cold air can infiltrate are also high-risk zones.

Copper pipes freeze more readily than other materials because metal conducts cold efficiently. However, PEX and even older galvanized steel pipes can freeze too. The key difference is that PEX has some flexibility and may not burst immediately when frozen, while rigid copper pipes often crack or split when water expands inside them. Interestingly, hot water pipes sometimes freeze before cold water pipes because hot water systems may have less residual flow.

In Ottawa's climate, pipes typically start freezing when temperatures drop below -10°C for extended periods, particularly during those brutal January and February cold snaps we experience. Pipes closest to exterior walls or in poorly insulated areas can freeze even when indoor temperatures seem comfortable. Wind chill and air infiltration around the foundation can create surprisingly cold microclimates around vulnerable pipes.

Prevention is crucial because burst pipes can cause thousands of dollars in water damage within hours. Keep cabinet doors open under sinks during cold snaps to allow warm air circulation, maintain consistent heating even when away, and consider having vulnerable pipes insulated by a professional. If you suspect a pipe is frozen (no water flow, frost on exposed pipes), shut off the main water valve and call for emergency service immediately.

For an assessment of vulnerable pipes in your Ottawa home and professional insulation solutions, Ottawa Pro Plumbing offers free consultations to help prevent costly freeze damage.