Winterizing

Winterizing a Seasonal Cottage Before Freeze-Up

Updated 2026-06-03 · About 10 minutes

An unheated building left for a Canadian winter faces two distinct threats: water that freezes where it should not, and snow that accumulates faster than the structure can shed it. Both are predictable, and both are far cheaper to prevent in October than to repair in April. This guide treats winterizing as a closing sequence — done once, in order, before the first sustained freeze.

Why water is the first concern

Water expands as it freezes. A pipe, trap, or fixture holding even a small volume can split when that water turns to ice, and the damage is usually invisible until the system is recharged in spring. The goal of plumbing winterization is simple to state and easy to under-do: remove the water, everywhere.

1. Shut off the supply at its source — the well pump and pressure tank, or the main valve.
2. Open the lowest drain and every fixture so the lines empty by gravity. Open taps at the high points too, so air can replace the draining water.
3. Clear the traps. Sink, tub, and toilet traps are designed to hold water; that water has to be removed or protected. Non-toxic plumbing antifreeze, the type sold for recreational vehicles and seasonal properties, is the common choice for traps and toilets.
4. Drain the water heater and any pressure tank according to its instructions.

Snow load: planning for weight

Roofs in snow country are built to carry a designed load, and in Canada that design value is set by local building requirements that reflect regional snowfall. Problems arise less from a single storm than from accumulation that lingers, drifts unevenly, or turns to dense, wet snow and ice.

• Watch the pattern, not just the depth. Drifting against a wall, a valley between two roof sections, or a low addition beside a tall wall can concentrate weight well beyond the open-field depth.
• Mind the ice. Compacted layers and ice are far heavier than fresh snow for the same depth. A roof that looks lightly loaded can be carrying more than it appears.
• Reach from the ground. Where removal is warranted, a roof rake used from ground level is safer than climbing onto a cold, sloped surface. Working on a snow-covered roof is a serious fall risk.

Ice dams begin in the fall

An ice dam forms when heat escaping through the roof melts the underside of the snowpack; the meltwater runs down to the cold eave, refreezes, and builds a ridge that traps the next round of water behind it. The trapped water then works back under the shingles.

The contributing factors are set long before winter:

• Blocked gutters and downspouts, which is why the fall gutter clear in the seasonal calendar matters so much.
• Heat leaking into the attic or roof cavity from a building that is not fully shut down.
• Poor ventilation that lets the roof deck warm unevenly.

For a seasonal cottage that is closed and unheated, the heat-loss side largely takes care of itself; the gutters do not.

Closing the building

With water and roof handled, the rest of the closing routine keeps the building secure and dry through months of absence.

Step	Detail
Power	Shut down circuits you do not need; leave only what is required for any monitoring you keep running.
Fuel	Close propane at the tank if appliances are off for the season.
Openings	Close and latch windows; check that vents and chimneys are screened against wildlife.
Interior	Leave interior doors and cabinets open so air can move and pockets of damp do not form.
Record	Write the date and what was done, so spring opening starts from a known state.

For the broader yearly rhythm this fits into, see the seasonal maintenance calendar. For the exterior surfaces that take the brunt of freeze-thaw cycles, see caring for wood siding, logs, and decks.