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PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
AGE of PLUMBING MATERIALS & FIXTURES
AIR DISCHARGE at FAUCETS, FIXTURES
ANTI SCALD VALVES
ANODES & DIP TUBES on WATER HEATERS
BACKUP PREVENTION, SEPTIC
BACKUP PREVENTION, SEWER LINE
BACKWATER VALVES, SEWER LINE
BATH & KITCHEN DESIGN GUIDE
CHEMICAL CONTAMINANTS in WATER
CHEMICAL ODOR SOURCES
CHLORINE IN DRINKING WATER
DEBRIS in WATER SUPPLY, Water Heater
DEPTH of SEPTIC TANK
DRAIN & SEWER PIPING
FAUCETS & CONTROLS, KITCHEN & BATH
FAUCETS, OUTDOOR HOSE BIBBS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOR DRAIN / TRAP ODORS
FLUSHOMETER VALVES for TOILETS URINALS
GAS PIPING, VALVES, CONTROLS
GALVANIC SCALE & METAL CORROSION
HARD WATER - SOFTENERS
HEAT TAPES, Heat, Insulation prevent Freeze-Up
LEAD POISONING HAZARDS GUIDE
LEAD IN DRINKING WATER, HOW to REDUCE
METHANE GAS SOURCES
MIXING / ANTI-SCALD VALVES
MUNICIPAL WATER PRESSURE IMPROVEMENTS
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER
ODORS, SEPTIC or SEWER
ODORS SEWER GAS in COLD WEATHER
ODORS, SULPHUR SMELL SOURCES
ANIMAL or URINE ODOR SOURCE DETECTION
PIPING IN BUILDINGS, Clogs Leaks Types
PLUMBING FIXTURES, KITCHEN, BATH
PLUMBING NOISE CONTROL
PLUMBING VENT DEFINITIONS & CODES
PLUMBING VENT DEFECTS & NOISES
PUMPS, WATER REPAIR
RELIEF VALVE LEAKS
RELIEF VALVES - TP Valves on Boilers
RELIEF VALVES - STEAM TP VALVES
RELIEF VALVES - Water Heaters
RELIEF VALVES - Water Tanks
REPAIR BURST LEAKY PIPES
METHANE GAS HAZARDS
SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SHUTOFF VALVE LOCATION, USE
SULPHUR & SEWER GAS SMELL SOURCES
SWEATING (CONDENSATION) on PIPES, TANKS
TOILETS, INSPECT, INSTALL, REPAIR
WATER, WELLS, WATER TANKS: TESTING GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMPS & TANKS
WATER SOFTENERS & CONDITIONERS
WATER SOURCE ALTERNATIVES
WATER SUPPLY & DRAIN PIPING
WATER SHUTOFF VALVE LOCATION, USE
WATER SHUTOFF VALVE, WELL PUMP
WATER TESTS, CONTAMINANTS, TREATMENT
WELLS CISTERNS & SPRINGS
WINTERIZE A BUILDING
This article describes the expansive force of freezing water, or the force exerted by ice as it freezes and expands. The pressure exerted by freezing water depends on temperatures and other physical conditions, but it can be tremendous - enough to lift buildings, burst pipes & plumbing fixtures, and crush the hulls of ships trapped in ice. Here we describe the typical effects of freezing water and ice on buildings and on or in building plumbing pipes & fixtures or in appliances such as water tanks or heating boilers.
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As we elaborate below, while water begins to crystallize into ice at 0°C (or 32°F), its expansive forces generally do not cause water pipes to burst until temperatures further fall to around 20°F.
The actual burst point for freezing pipes has more variables including the pipe material, thickness, and even possibly its overall diameter and shape. But 20°F is a good number for the freeze point of pipes.
Does Leaving a Faucet Open Prevent Freezing Pipes from Breaking?
We know that running water, by moving warmer water from some building locations to colder pipe locations that would otherwise freeze, we can defer or even prevent frozen water supply pipes.
Watch out: at DE-WINTERIZE a BUILDING we warn that while running water may prevent supply pipes from freezing you may cause the building drain to freeze, block and even burst. Some building experts advice that when faced with freezing pipes or already-frozen water pipes we open the faucets, reasoning that if pipes are frozen you might reduce the chances of freeze-burst piping or reduce its extent by opening faucets.
Allowing even a small amount of water (from the un-frozen pipe sections) to drain out of the building supply piping might reduce some of the in-pipe pressure even if no water is flowing from the faucet. - Building Research Council (1996)
Horizontal freezing water-forces (ice pressure) along piping lengths
An exception to our horizontal split burst frozen pipe rule that describes what we have observed most often in buildings is the occasional separation of pipes at 90 degree elbow solder joint (photo at above left). In the photo above we show that clearly horizontal forces along the pipe pushed this pipe joint apart. But look more closely at the solder joint and you will see that the original soldering job was poorly executed without proper cleaning and use of flux. The solder was not bonded to the copper and was not uniform in the joint - this was a weak point in the piping system so it's no surprise that the pipe failed here.
Lateral water freeze-forces (ice pressure) across building piping
More often, where I observed that pipe joint separation a plumbing elbow (a common freeze point in buildings), often the elbow of bronze rather than just thin-walled copper resisted splitting while nearby softer copper piping did not.
While expanding ice inside of water supply pipes may slightly increase pressure (as water is not compressible) our field experience and photos of frozen burst pipe such as the photographs at immediate left and again at below left suggest that most often frozen water pipes burst or split from the expanding ice pressure within a small section of pipe, creating first a bulge and then a split from forces across the diameter of the pipe rather than along its length.
It certainly appears from physical evidence that the water pipe shown in my photo bulged and then split by forces across the diameter of the pipe.
A rational view is that freezing water applies force in all directions rather uniformly. But the damage done by that force occurs where the force is confined. But freezing water appears to be immediately confined more by the circumference of a pipe than along its length. Why might this be? Perhaps because the expansive force of ice increases as the temperature of the freeing water drops. A plug of ice forms in the pipe, the continues to expand as temperatures drop.
Why then might forces across the pipe be more confined than forces along the water pipe? We are not sure we not agree with one building expert who opines that the fill valve on toilets allows water, pushed along by freezing ice, to enter toilet tanks.
Really? Building water pressure varies over a range all the time for a variety of reasons (faucets open and shut, pumps starting and stopping) without ever pushing water through a closed toilet tank fill valve.
But there are building components that can absorb increasing water pressure:
Depending on its state, freezing water (or ice as temperatures continue to drop) can expand by as much as nine percent at a maximum force between about 25,000 and 114,000 psi.
Actually water reaches its maximum density above freezing, at about 4°C. It is the expansion of ice as it continues to freeze that explains why icebergs float - the iceberg displaces a volume of water that weighs more than the (expanded) ice itself. The tip of an iceberg seen above water usually represents about 8% of the iceberg's total volume.
Stated another way we can explain why ice is lighter than water by explaining its expansion as water changes from liquid to frozen state.
As ice freezes forming hexagonal crystals (comprised of two H molecules join with an O molecule at an angle of 104°) the water in this form takes up more space than liquid water. But the crystals formed by freezing water take on varying forms (and affecting the pressures exerted by confined ice) as temperatures continue to fall. - Debenedetti (2003)
Before modern physicists and engineers began calculating the expansive force of freezing water, Florentine academics had measured the strength of freezing water by enclosing water in a brass globe of known thickness and strength, then allowing it to freeze. Those academics observed that a one-inch globe of water, when freezing, could exert a 27,000 pound force. - Platts (1880)
Expanding ice forces are very strong when confined. Entire building movement caused by freezing and ice are discussed at FOUNDATION DAMAGE by ICE LENSING and at COLD WEATHER ROOF TROUBLE.
During normal plumbing use the surge of wastewater down the drain makes it past this cold spot without freezing. But a dripping faucet or running toilet, sending a small but continuous trickle of water down the drain can accumulate as ice until it expands, blocks the drain (leading to a sewage backup in the building) or until the drain line freezes and breaks.
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