Pipes rarely need a long deep freeze to run into trouble. In St. Louis, a sharp overnight cold snap can reach supply lines that sit in exterior walls, under cabinets on outside walls, in attics, in garages, and in crawl spaces where cold air moves freely. When water inside a pipe freezes, it expands, and the pipe can split. The damage often shows up later, when the ice melts and a leak starts inside a wall or floor. A short round of preparation before the first hard freeze is far easier than cleaning up after one.
Find the pipes most at risk
Walk through the house on a cold day and note where you feel drafts or where a pipe runs close to the outside. Common trouble spots include:
- Supply lines under kitchen and bathroom sinks on exterior walls
- Pipes along rim joists in basements and crawl spaces
- Pipes in garages, utility rooms, and unheated additions
- Pipes in attics or near gaps around vent stacks
- Outdoor hose bibs and irrigation or sprinkler lines
Seal and insulate
Cold air often reaches pipes through small gaps. Seal openings where pipes pass through the rim joist, sill plate, or floor with caulk or expanding foam, following the product label. Then wrap exposed pipes in foam pipe sleeves, which are sold at most hardware and home supply stores. Insulation slows heat loss but does not add heat, so it works best when the home stays warm. Heat tape is another option for pipes in very cold spaces. Use only heat tape made for that purpose, install it as directed, and check its cord and thermostat each year.
Prepare the outdoor faucets
Outdoor faucets are a common source of cracked pipes. Before the first freeze, disconnect and drain garden hoses. If your home has an interior shutoff for an outdoor faucet, close it, then open the outdoor faucet so any remaining water can drain, and leave it open. Cover each hose bib with a fitted insulated cover. For irrigation systems, have the lines drained or blown out by a qualified contractor before cold weather arrives.
Keep the house warm and the air moving
Keep the thermostat at a steady setting day and night, including when you are away. Setting the heat very low to save energy can let rooms along exterior walls cool enough for pipes to freeze. Open cabinet doors under sinks on exterior walls so warm room air can reach the pipes. Keep garage doors closed when the space is not in use, and do not run a space heater near stored items or cords.
Run water on the coldest nights
When a hard freeze is forecast, let a faucet on an exterior wall drip slowly. Moving water is less likely to freeze, and a small flow can help relieve pressure in the line. A thin stream uses some water, which is a fair tradeoff on a night when freezing is a real risk. Choose a faucet at the far end of the line from the main shutoff, and keep it running through the coldest hours.
If a pipe freezes
Frozen pipes can often be thawed safely if you act early. Start by opening the faucet served by the frozen line, since melting water needs a way out. Then warm the frozen section gently with a hair dryer, an electric heating pad, or warm towels, starting nearest the faucet and working toward the frozen spot. Do not use an open flame, a torch, or a fuel-burning heater inside the home. Never leave a heat source unattended.
If you see water spraying from a wall, ceiling, or pipe, or if flow stops after you thaw a line, shut off the main water valve right away. Know where that valve is before you need it, and label it clearly. Then call a licensed plumber in your area to inspect and repair the damage. If you smell gas or hear hissing near a gas appliance, leave the home and call your gas provider from outside.
Winter in St. Louis brings long stretches of cold punctuated by sudden drops, so most of the work happens in autumn. Walk the house, seal the gaps, insulate exposed lines, and set up outdoor faucets before the first hard freeze. Keep the house heated through the season, and keep a plan in mind so you can act quickly if a pipe stops running.