📰How to Prevent Burst Pipes in New England Winters

Why pipes burst in winter — the physics

Water expands approximately 9% in volume when it freezes. In a sealed pipe with no room for expansion, the ice plug creates pressure that can reach thousands of PSI on the water column between the frozen section and closed fixtures. This pressure does not burst the pipe at the ice plug itself — it bursts at weak points downstream, typically at joints, elbows, or thin-walled sections.

The pipes most vulnerable to freezing are those in unheated spaces: exterior walls with inadequate insulation, crawl spaces, unheated garages, attic penetrations, and areas near exterior doors or vents. Supply pipes in these locations are exposed to outdoor temperature fluctuations and can freeze when outdoor temperatures drop below 20°F for extended periods or when wind chill is factored in.

Prevention step 1 — Insulate exposed pipes before winter

Pipe insulation (foam tube insulation available at any hardware store) should be installed on all supply pipes in unheated spaces: crawl spaces, basement rim joist areas, garage areas, and any supply pipe running through an exterior wall. Foam pipe insulation slows heat loss from the pipe, extending the time it takes for pipe temperature to drop to freezing even when ambient temperature is well below 32°F.

For pipes in exterior walls that have already frozen in past winters, the long-term solution is improving wall insulation so the pipe side of the wall cavity stays above 32°F. This may require sealing air gaps and adding blown insulation through the exterior or interior — a home energy auditor can identify the most effective approach without full wall deconstruction.

• Install foam pipe insulation on all supply pipes in unheated spaces
• Pay special attention to rim joist areas, crawl spaces, and garage supply pipes
• For pipes in exterior walls, improve wall insulation to eliminate the cold side
• Seal air gaps around penetrations — cold air infiltration accelerates freezing

Prevention step 2 — Address exterior wall pipes

Kitchen and bathroom pipes on exterior walls are responsible for a significant proportion of winter pipe bursts in older New England homes. The 1960s-1980s construction common throughout the region often has supply pipes run in exterior walls with minimal insulation on the exterior side, creating a pipe that is essentially exposed to outdoor temperatures on one face.

The reliable fix for exterior wall pipes is to move them to interior walls when the kitchen or bath is renovated, or to add rigid foam insulation to the exterior of the building (exterior continuous insulation) that moves the freezing plane well outside the wall cavity. Cabinet heat tape — electric heating tape wrapped around specific vulnerable pipes — is an interim solution for known problem pipes.

Prevention step 3 — Thermostat and vacancy protocols

The single most common cause of burst pipes in New England is vacancy during a cold snap — whether a weekend away, a holiday trip, or a property left vacant between tenants. When the home is unoccupied and the thermostat is set below 55°F, pipes that were previously marginal become vulnerable.

The standard recommendation is to maintain indoor temperature at 55°F minimum during vacancy. This is not just a comfort measure — it is the threshold at which most building envelopes maintain above-freezing temperatures in wall cavities and crawl spaces, provided insulation is reasonably adequate. Set the thermostat on your smart home system to alert you if temperature drops below 58°F during vacancy.

For extended vacancy (weeks or months), the professional recommendation is to shut off the main water supply and drain the system. This eliminates burst pipe risk entirely and removes the temperature dependency. Contact your plumber to drain the system properly — some fixtures and low points need specific attention for complete draining.

• Minimum thermostat setting of 55°F during all periods of vacancy
• Set smart thermostat alerts for temperature below 58°F
• For vacancy longer than one week in cold season, shut off and drain the system
• Open cabinet doors under kitchen and bath sinks to allow heated air to reach pipes

What to do if a pipe bursts

Shut off the main water supply immediately at the shutoff valve near the meter. Open all faucets to drain remaining water from the supply system and relieve any remaining pressure. Call a licensed plumber for the pipe repair and call your water damage restoration company for the resulting water damage.

Do not attempt to thaw a frozen pipe with an open flame — this is a documented fire hazard. Use a hair dryer or heat lamp applied carefully, working from the open faucet end toward the frozen section, never from the frozen section inward. Document the damage before cleanup begins for the insurance claim.

Frequently asked questions

How cold does it have to be for pipes to freeze?

Pipes can freeze at outdoor temperatures below 20°F, but the critical factor is how well insulated the pipe's location is. Pipes in exterior walls with poor insulation can freeze at 28-30°F with wind chill. Well-insulated pipes in conditioned spaces are protected at much lower temperatures. Duration matters — a short dip below 20°F is less risky than sustained cold over 24-48 hours.

Should I let faucets drip during a cold snap?

Yes — a slow drip from faucets fed by vulnerable pipes prevents pressure buildup from ice plug formation. Moving water is harder to freeze than static water, and the drip provides pressure relief if freezing begins. This is a short-term mitigation for known cold events, not a substitute for proper insulation.

How much damage can a burst pipe cause?

A burst pipe can release hundreds of gallons per hour before it is detected and the supply is shut off. If the burst occurs in a vacation home or unoccupied property, it may run for days. Insurance industry data consistently shows burst pipe claims as among the most costly single water damage events in the country — often $20,000 to $70,000 or more in damage to structure and contents.