I’ve owned five houses in climates that hit -20°F. I’ve had pipes freeze in a crawlspace, in an exterior wall, and once under a kitchen sink because a cabinet door was closed. Every time, the fix came down to the same thing: catching it early and applying heat the right way. Here’s exactly what I do, what I avoid, and the one tool I’ll never go without.
How To Tell If A Pipe Is Frozen (Before It Bursts)
You don’t need a thermal camera. You need to know what to look for.
The Obvious Signs
Turn on a faucet. If nothing comes out — or just a trickle — and the weather has been below freezing for more than 12 hours, you’ve got a frozen line. Don’t check one faucet. Check every faucet. A frozen pipe in the basement might kill water to the second-floor bathroom only.
The Subtle Signs Most People Miss
Frost on an exposed pipe is a dead giveaway. But I’ve also caught frozen pipes by putting my hand on the wall. If a section of drywall feels cold to the touch while the rest of the room is warm, there’s likely a frozen line behind it. Another tell: strange smells from a drain. When the trap freezes, sewer gas can back up into the house.
When To Panic
If you hear a hissing sound or see water stains on the ceiling or wall, the pipe has already burst. Shut off the main water valve immediately. Don’t try to thaw anything until the leak is stopped. I keep a SharkBite 1/2-inch push-to-connect cap ($4 at Home Depot) in my emergency kit for exactly this reason.
One more thing: if the frozen section is in an exterior wall and you can’t access it from inside, call a plumber. Cutting into drywall with a frozen pipe behind it is a bad idea — one slip and you’ve got a geyser.
Thawing A Frozen Pipe: The Right Tools And The Wrong Ones
I’ve tried every method. Some work. Some will cost you a new house.
| Method | Time To Thaw (3-ft section) | Safety Risk | My Verdict |
|---|---|---|---|
| Hair dryer (low heat) | 20-40 minutes | Low | Best for accessible pipes |
| Heat tape (self-regulating) | 1-2 hours | Very low | Best for crawlspaces |
| Space heater (indirect) | 45-90 minutes | Medium (fire risk) | Good for cabinets |
| Propane torch | 2-5 minutes | Extreme | Never use this |
| Hot water (poured) | 10-20 minutes | Low | Only for outdoor spigots |
What I Actually Use
For pipes I can reach — under a sink or in a basement — I grab my Conair Pro hair dryer ($25, 1875 watts). I set it to low heat and high fan, and I move it back and forth along the frozen section. Never stay in one spot. You want to warm the pipe gradually, not scorch the paint off it.
For pipes in a crawlspace or attic, I use Frost King HC12A self-regulating heat tape ($35 for 12 feet). It wraps around the pipe and plugs into a standard outlet. Self-regulating means it won’t overheat and melt itself. I leave it on until the pipe thaws, then I keep it plugged in for the rest of winter as prevention.
What I Never Do
Do not use a propane torch. I know a guy who melted a pinhole in his copper pipe and flooded his basement. Do not use a heat gun on high. I’ve seen the plastic on PEX pipes bubble and warp. Do not pour boiling water down a drain to thaw a trap — it can crack the PVC. Warm water, yes. Boiling, no.
Prevention: The Only Thing That Actually Works Long-Term
Thawing a pipe is emergency response. Prevention is the part most homeowners skip because it requires crawling under the house in November. Do it anyway.
Insulate the right pipes. Not all of them. Focus on the ones in unheated spaces: crawlspaces, attics, garages, and exterior walls. I use Armacell AP Armaflex 1/2-inch self-seal pipe insulation ($1.50 per foot at Lowe’s). It slides over the pipe and the adhesive flap seals itself. For corners, buy the mitered 90-degree fittings — they’re $3 each and worth every penny because a gap at a joint is where ice forms.
Seal air leaks. A frozen pipe is usually caused by a draft, not just cold air. Check around the pipe where it enters the house. If you see daylight or feel a breeze, fill the gap with Great Stuff Gaps & Cracks insulating foam ($8 per can). Let it cure for 24 hours, then trim it flush.
Let faucets drip. When the forecast says single digits, open the faucet farthest from the main supply line to a slow trickle. Moving water freezes at a lower temperature than standing water. A drip uses about 5 gallons per day — that’s pennies on your water bill compared to a burst pipe repair.
Open cabinet doors. This one is free. If your kitchen sink is on an exterior wall, open the cabinet doors underneath to let warm room air circulate around the pipes. I do this every night from December through February.
What To Do If The Pipe Has Already Burst
This is the part nobody wants to think about. But if you catch it fast, the damage is manageable.
Step 1: Shut Off The Water
Find the main shutoff valve. In most houses, it’s in the basement near the front wall, or in a utility closet. Turn it clockwise until it stops. If the valve is stuck (and they often are), use a pair of pliers or a valve wrench. If it won’t budge, call the water company — they can shut it off at the meter.
Step 2: Drain The System
Open every faucet in the house, starting with the highest one (usually a second-floor bathroom) and working down to the basement. This relieves pressure and drains the water that’s left. Flush every toilet once.
Step 3: Patch The Leak Temporarily
For a small pinhole leak in a copper pipe, I use Epoxy Putty ($6 at any hardware store). Knead it until it’s warm, press it over the hole, and hold it for 5 minutes. It buys you enough time to call a plumber. For a larger split, use a pipe repair clamp — the Dresser Style 90 clamp ($12) comes in 1/2-inch and 3/4-inch sizes. Wrap the rubber gasket around the pipe, put the metal halves over it, and tighten the bolts. It’s not permanent, but it stops the flood.
Step 4: Call A Plumber
Even if your patch holds, get a professional to replace the damaged section. I’ve seen epoxy patches fail six months later when the pipe expands and contracts. A plumber will cut out the burst section and sweat in a new piece of copper or replace it with PEX. Expect to pay $200-$500 for a simple repair, more if the pipe is inside a wall.
When NOT To Fix It Yourself (And Why Calling A Pro Saves Money)
I’m a DIY guy. I’ve rewired a light switch, replaced a toilet flange, and built a deck. But some frozen pipe situations are not worth your time.
If the frozen section is inside an exterior wall. You can’t thaw it effectively with a hair dryer through drywall. You’d need to cut a hole, and if you hit the pipe with a saw, you’ll create a burst. A plumber with a thermal imaging camera can locate the exact spot and cut a small access panel. Cost: $150-$300 for the visit. Cost of cutting a 4-foot hole in the wrong spot: $500 in drywall repair.
If the pipe is buried in concrete. I had a slab foundation house with a copper line running through the floor. It froze every other winter. No amount of heat tape or insulation helped because the cold was coming from the ground. A plumber re-routed the line through the attic. Cost: $800. But it never froze again.
If you smell gas. If you use a space heater or heat tape near a gas line and you smell rotten eggs, get out of the house and call the gas company. Do not try to fix a frozen gas pipe. That’s a job for a licensed professional.
If the pipe is old galvanized steel. Galvanized pipes rust from the inside. When they freeze, the ice expands and cracks the rust-weakened metal. Even if you thaw it successfully, the pipe is compromised. Replace the entire run. I recommend switching to Uponor PEX-A tubing ($0.60 per foot) — it’s flexible, resists freezing better than copper, and one person can install it with a crimp tool.
Here’s my bottom line: if you can reach the frozen pipe and it’s copper or PEX, thaw it yourself with a hair dryer or heat tape. If it’s inside a wall, in concrete, or made of galvanized steel, call a plumber. The $200 service call is cheaper than the water damage from a burst pipe you tried to thaw with a torch.
