The Short Answer
Set your thermostat to “hold” a few degrees warmer, open the cabinet doors under sinks on exterior walls, and run a thin stream of warm water from vulnerable faucets. Wind combined with single-digit temperatures is what freezes pipes.
I've had a few calls this week about freezing pipes, and with overnight temperatures dropping into the single digits, I want to get ahead of it.
Ultra-cold weather combined with high winds is the dangerous combination. Wind drives the cold further into your walls than temperature alone, and that's where the pipes are.
Turn the heat up a couple of degrees and set the thermostat to "hold." That keeps it from dropping the temperature overnight, which is exactly when you don't want it dropping. I know nobody likes paying for that. But it's far cheaper to walk around the house in shorts for a few days than to deal with frozen pipes, a ceiling coming down, and water damage to your house and everything in it.
Open the cabinet doors under your sinks. In kitchens and bathrooms where the plumbing runs along an exterior wall, leaving those vanity doors open at night lets warm air circulate around the pipes. Not sure if you have pipes in an exterior wall? If there's a window over your kitchen sink or bathroom vanity, you almost certainly do. Those are the pipes that freeze.
Let the vulnerable faucets run a thin stream of warm water. Moving water freezes slower than still water. The same rule applies in the bathroom — if your shower or tub faucets are on an exterior wall of the house, the supply lines feeding them are in that wall too. Those are perfect candidates for this.
Stay warm, keep the house warm, and know where your water main shutoff is.
Common Questions
At what temperature do pipes freeze?
Pipes start to freeze when the temperature drops below 20°F, especially if there's wind. Wind drives cold air into wall cavities where the pipes actually are. The combination of single-digit temps and high wind is the real danger. Keep your thermostat above 55°F and you're in good shape.
Should I leave my faucet dripping all night?
Yes, for faucets on exterior walls. A thin stream of warm water — not just a drip — keeps water moving through the pipe, and moving water freezes slower than still water. It costs pennies compared to what a frozen pipe costs to fix.
What do I do if my pipes are already frozen?
First, shut off your water main so you don't flood the house when it thaws. Then open the faucet so water has somewhere to go as it melts. Use a hair dryer or space heater on the exposed pipe — never an open flame. If you can't reach the frozen section, call a plumber right away.
Have a question about your own house?
I talk to every customer myself. Call the shop and ask.