❄️ Frozen Pipes: Prevention, Thawing, and What NOT To Do

Last updated: February 2025

It's -5°C outside. You turn the tap. Nothing comes out. Your pipes are frozen solid.

Here's what's happening, how to fix it safely, and how to prevent it happening again. From someone who's thawed 100+ frozen pipes every winter.

Why Pipes Freeze (And Why It Matters)

Water expands 9% when it freezes. Pipe doesn't expand. Something's gotta give. The pipe splits.

The dangerous part? You don't know it's burst until it thaws. Ice is plugging the hole. When ice melts? Water everywhere.

Which pipes freeze first:

• Loft pipes: Cold, often uninsulated, exposed to roof temperature
• External wall pipes: Cold radiates through wall, freezes pipes in the cavity
• Garage/outbuilding pipes: Unheated spaces
• Under suspended floors: Cold air circulation underneath
• Outdoor taps: Exposed, no heating, usually forgotten

When pipes freeze: Usually at -3°C to -5°C sustained for 6+ hours. Colder = faster. Windchill makes it worse.

Prevention: £20 of Insulation Beats £500 Emergency Callout

1. Insulate Pipes (30 Minutes, £15-30)

What you need:

• Foam pipe insulation (B&Q, Screwfix, £12-25 for 6-8m)
• Scissors or knife to cut to length
• Insulation tape to secure joins

Which pipes to insulate first:

1. All loft pipes (cold water tank feeds, overflow)
2. Pipes on external walls (especially north-facing)
3. Pipes in garages, sheds, outbuildings
4. Under-floor pipes (if accessible)
5. External taps

How to fit: Foam insulation splits lengthways. Open it up, slide over pipe, close around pipe, tape joins. Done. Five-year-old could do it.

2. Heating Strategy (When It's Forecast Below Zero)

Don't turn heating off at night. Set it to 15°C minimum. Costs £2-5/night. Emergency plumber costs £350+. You do the math.

Open loft hatch slightly: Lets warm air rise into loft. Keeps pipes above freezing.

Open cupboard doors: Under-sink pipes stay warmer if cupboard door is open (lets room heat in).

Drip taps overnight: Moving water doesn't freeze easily. Leave cold tap dripping (very slightly—pencil-lead width stream). Annoying but effective.

3. If You're Going Away in Winter

Option 1: Leave heating on (safest)

• Set thermostat to 15°C minimum
• Have someone check daily (neighbor, friend)
• Leave them spare key and your phone number
• Cost: £30-60/week depending on house size

Option 2: Drain the system (cheaper but risky)

1. Turn off water at stopcock
2. Turn off boiler/immersion heater
3. Open all taps (hot and cold, every sink/bath)
4. Flush all toilets
5. Open drain valve on lowest radiator

Problem with Option 2: If you miss a valve, or a trap still has water, or you don't drain fully—it freezes anyway. And now you come home to a dry system that needs refilling/bleeding. Only do this if confident.

How To Tell If Pipes Are Frozen

Symptoms:

• Turn tap—nothing comes out (or very weak trickle)
• Only one tap affected (e.g., bathroom cold tap works, kitchen doesn't—the frozen section is between)
• Radiators not heating up (heating pipes frozen)
• Toilet cistern not refilling after flush
• Strange noises (banging, gurgling) when trying to run water

How to locate the freeze:

1. Work out which tap isn't working
2. Trace pipe back to where it comes from (usually loft or external wall)
3. Feel pipes—frozen section will be very cold, maybe frost visible
4. Look for bulges in pipe (ice expanding it)

Safe Thawing Methods (What Actually Works)

✅ Safe Methods (In Order of Effectiveness):

Method 1: Hairdryer (Best for Accessible Pipes)

• How: Move hairdryer along pipe slowly, back and forth
• Time: 15-45 minutes depending on length of freeze
• Safety: Keep away from water. Don't overheat one spot.

Method 2: Hot Water Bottles / Towels

• How: Wrap hot (not boiling) water bottles around pipe. Or soak towels in hot water, wrap around pipe, replace when cool.
• Time: 30-60 minutes
• Good for: Pipes you can't reach with hairdryer (behind walls, under floors)

Method 3: Space Heater in Room

• How: Portable heater in room, directed at frozen pipe area (not directly on pipe—ambient heat)
• Time: 1-3 hours
• Good for: Entire room of frozen pipes (loft, garage)

Method 4: Turn Heating Up

• How: Crank heating to maximum, open all cupboard doors, wait
• Time: 2-4 hours
• Good for: Mild freezing (no hard blockage yet)

Thawing Tips:

• Start thawing from tap end and work backwards (toward incoming supply)
• Open the tap (when ice melts, water can escape)
• Don't leave heating unattended (fire risk)
• Check pipe for bulges/splits while thawing (turn water off at stopcock if you see damage)

When To Call a Plumber (Don't DIY This)

Call immediately if:

• Pipe has visible bulges or splits (it's already burst—just frozen shut)
• You can't access the frozen section (under floorboards, behind walls)
• Multiple pipes frozen (whole system issue)
• Thawing attempts failing after 2 hours
• Water starts leaking as you thaw (burst pipe)

What a plumber does:

• Locate exact freeze point (thermal imaging camera)
• Thaw safely with professional equipment
• Pressure-test system for splits/bursts
• Repair any damage before it becomes a flood
• Advise on insulation improvements

What Happens When Frozen Pipes Thaw

Scenario 1: Pipe Was Fine (Lucky)

Ice melts. Water flows. No leak. Celebrate. Then insulate that pipe so it doesn't happen again.

Scenario 2: Pipe Split (Common)

Ice melts. Water starts spraying/dripping. Now you have a burst pipe. Turn off water at stopcock immediately. Call emergency plumber.

How to check:

1. As pipe thaws, WATCH IT like a hawk
2. Look for water beading, drips, spray
3. Listen for hissing (water escaping under pressure)
4. If you see/hear anything suspicious, turn water off

Insurance Coverage (Does It Pay?)

✅ Usually covered (buildings insurance):

• Burst pipe repair from freezing
• Water damage from burst frozen pipe
• Emergency call out costs

❌ Usually NOT covered:

• Freezing damage if property was "unoccupied and unheated"
• Gradual damage (you knew it was frozen for days, did nothing)
• Outside pipes/external taps (check your policy—often excluded)

Common Mistakes (What NOT To Do)

❌ Using a blowtorch/heat gun on high: Causes thermal shock, melts pipes, starts fires. Just don't.

❌ Pouring boiling water on pipes: Thermal shock can crack copper or split joints. Use hot (not boiling) water.

❌ Ignoring it ("it'll thaw by itself"): Maybe. But if it's burst, you're flooding your house slowly. Check it.

❌ Turning water on full blast before checking for leaks: If pipe burst, you've just created a geyser. Turn on gently, watch for leaks.

❌ Not insulating after a freeze: It'll freeze again in the next cold snap. Insulate it NOW while you remember.

Quick Prevention Checklist (Before Winter)

1. ☐ Insulate loft pipes (£15-30, 30 minutes)
2. ☐ Insulate external wall pipes (any you can access)
3. ☐ Insulate external taps (or turn off and drain)
4. ☐ Fix dripping taps (drips freeze into icicles that block pipes)
5. ☐ Know where stopcock is (test it turns)
6. ☐ Check loft insulation (should be 270mm depth minimum)
7. ☐ Service boiler (don't want it failing in a freeze)

Emergency Action Plan (If Pipes Freeze Tonight)

1. ☐ Check all taps (which ones don't work?)
2. ☐ Turn heating up to maximum
3. ☐ Open cupboard doors (under sinks especially)
4. ☐ Locate frozen section (trace pipe from affected tap)
5. ☐ Thaw safely (hairdryer, hot water bottles—no blowtorch)
6. ☐ Open tap slightly (lets water escape as ice melts)
7. ☐ Watch for leaks (as pipe thaws, check for splits)
8. ☐ Call plumber if: can't access pipe, no thawing progress, leak appears

Need Help Right Now?

National Plumbing Dispatch: 0333 600 0990

24/7 frozen pipe emergency service. Thermal imaging to locate freeze. Professional thawing equipment. Pressure testing for splits. Repairs done same visit.

We get 100+ frozen pipe calls every cold snap. We know what works, what doesn't, and what's dangerous. If DIY thawing isn't working or you've got a leak, call us. We'll get your water back on safely.

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