If a frozen pipe bursts in your Woodstock home, shut off the main water valve first. Then cut power to any wet rooms from a dry spot, open the faucets to drain the lines, and start getting water off the floor. The sooner the flow stops, the less drying and repair your house will need.

Woodstock is the county seat of McHenry County, about 51 miles northwest of Chicago, and winter here is the real thing. Cold snaps that hold below freezing for days are a normal part of the season.

The city is known for its historic Square, where brick streets surround the Old McHenry County Courthouse from 1857 and the Woodstock Opera House from 1889. A town with that much history has houses from many eras, and newer homes toward McHenry and Crystal Lake have their own cold spots too.

Why do pipes freeze and burst?

Pipes burst because water expands when it turns to ice. The ice forms a plug inside the pipe, and pressure builds in the water trapped between that plug and the closed faucet. The pipe or a fitting gives way at its weakest point.

That is why the split is often not where the ice was. It is also why many bursts are found during the thaw. While the plug is frozen, little water escapes. When the temperature climbs and the ice lets go, the full pressure of the supply line pours out of the break.

Which pipes freeze first?

The pipes that freeze first are the ones closest to outside air and farthest from the heat. In most houses that means a short list.

• Supply lines inside exterior walls, especially behind kitchen and bathroom cabinets on the north side.
• Pipes in crawl spaces, attics and unheated garages.
• Lines that run through a rim joist or above a garage ceiling to reach a room over it.
• Outdoor faucets and the pipe just inside the wall that feeds them.
• Plumbing in additions, enclosed porches and rooms where the heat is turned down or the vents are closed.

Wind makes it worse. A small gap around a cable, a dryer vent or a sill plate can let a stream of very cold air blow directly onto a pipe.

How can you tell a pipe is frozen before it bursts?

The clearest sign is a faucet that gives a trickle or nothing at all on a very cold morning while other faucets work. A toilet that will not refill is another one.

Look at any pipe you can see. Frost on the outside, a bulge, or a section that feels much colder than the rest tells you where the ice is. Odd smells from a drain can also mean a line is blocked with ice.

If you catch it at this stage, you have a chance to thaw it before anything breaks.

How do you thaw a frozen pipe safely?

Thaw a frozen pipe with gentle, steady heat and an open faucet. Turn on the faucet the pipe feeds, both hot and cold, so melting water has somewhere to go.

Warm the pipe with a hair dryer, a heating pad or towels soaked in hot water. Start at the faucet end and work back toward the frozen section. Open cabinet doors and raise the thermostat a few degrees to help.

Never use a torch, a heat gun on high or any open flame. Besides the fire risk, fast heat can crack the pipe. If you cannot find the frozen spot, cannot reach it, or the pipe already looks split, shut off the main valve and call a plumber.

First steps when a frozen pipe bursts

These are the steps for the first hour and the first day, in order.

1. Shut off the water. Close the main valve, usually found where the water line enters the house near the meter. Turn a wheel handle clockwise or a lever handle a quarter turn.
2. Make the electricity safe. Switch off breakers for the wet rooms if you can reach the panel while standing on a dry floor. If water is near the panel, stay back and call your utility.
3. Drain the lines. Open cold faucets throughout the house and flush the toilets to empty the pipes. Turn off the water heater, then open the hot taps too.
4. Take photos and video. Record the break, the standing water, wet ceilings and walls, and damaged belongings before you move them.
5. Remove what water you can. Use mops, towels and a wet vacuum on floors. Set buckets under ceiling drips.
6. Relieve a sagging ceiling carefully. If drywall overhead is bulging with water, keep people out from under it. Leave it to a professional if you are unsure.
7. Protect your belongings. Lift furniture legs onto blocks or foil, pull up wet rugs, and carry electronics, papers and photos to a dry room.
8. Keep the heat on. Warm air helps drying and protects the rest of the plumbing. Do not turn the furnace off in a house with frozen lines.
9. Make your calls. Reach a plumber for the pipe repair, a restoration company for the drying, and your insurance agent to report the loss.
10. Save the broken pipe section. If the plumber cuts it out, keep it. Your adjuster may want to see it.

What makes Woodstock homes vulnerable to frozen pipes?

Woodstock's housing covers a long span of years, and each era has a weak point when the temperature drops.

The downtown is built around a turn-of-the-century square, and it is listed on the National Register of Historic Places. Older houses in general were often built before modern insulation, and many have had plumbing added or rerouted over the decades. Pipes ended up in outside walls, under porches and through crawl spaces because that was where they fit.

Newer houses are better insulated, though they still have cold spots. Bonus rooms over garages, kitchen sinks on exterior walls and plumbing in vaulted spaces all show up on frozen pipe calls.

The city covers about 13 square miles across parts of four townships, so some houses are well out from the center. A break in a house that sits empty during the workday, or for a week over the holidays, can run for a long time before anyone sees it.

What happens to a house after a pipe bursts?

Water from a supply line spreads farther than most people guess. It runs along framing, drops through ceiling fixtures, soaks insulation and wicks up drywall from the floor.

The surfaces you can see are only part of it. Subfloor under vinyl or hardwood, the cavity behind baseboards, and insulation inside walls hold moisture long after the carpet feels dry to the touch. Wood flooring can cup, drywall can sag and stain, and trim can swell and pull away.

Mold is the other clock running. EPA guidance is to get wet materials dry within 24 to 48 hours so growth does not start, and that short window is the main reason to act the same day.

How is frozen pipe water damage dried and repaired?

Professional drying starts with finding all the water. Technicians use moisture meters and thermal cameras to trace where it went, including rooms below and beside the break.

Standing water is extracted. Wet carpet pad, soaked insulation and drywall that cannot be dried in place are removed. Air movers and dehumidifiers are then set up and left running, and moisture readings are taken each day until the structure is back to its normal dry level.

Repairs come after the drying is confirmed: new drywall, paint, flooring and trim. Closing up a wall while the framing is still damp traps moisture inside, which is the outcome everyone wants to avoid.

What if you were away when the pipe broke?

Do the same first steps, with extra care. Water that has been running or sitting for days may have weakened ceilings and floors, so look before you walk in.

Shut off the water, make the power safe and document everything in detail. Tell your insurance company how long you were gone. Your insurer decides what your policy covers, and they will ask about dates and whether the heat was left on.

Before your next trip in cold weather, set the thermostat no lower than the mid 50s, shut off the main valve, and ask a neighbor to check the house.

Dealing with a burst pipe in Woodstock?

If a frozen pipe has left water in your home in Woodstock or elsewhere in McHenry County, contact ServiceMaster Kwik Restore for water removal, structural drying and repairs.