THIS SUDDEN DEEP FREEZE WILL CAUSE PROPERTY DAMAGE FROM NON-WINTERIZED PIPE BURSTS EVEN IN SOUTHERN HOMES
REGIONAL DIFFERENCES - WHY PIPES BURST IN SOUTHERN CLIMATES
Surprisingly, ice forming in a pipe does not typically cause a break where the ice blockage occurs. It’s not the radial expansion of ice against the wall of the pipe that causes the break. Rather, following a complete ice blockage in a pipe, continued freezing and expansion inside the pipe causes water pressure to increase downstream -- between the ice blockage and a closed faucet at the end. It’s this increase in water pressure that leads to pipe failure. Usually the pipe bursts where little or no ice has formed. Upstream from the ice blockage the water can always retreat back towards its source, so there is no pressure build-up to cause a break. Water has to freeze for ice blockages to occur. Pipes that are adequately protected along their entire length by placement within the building’s insulation, insulation on the pipe itself, or heating, are safe.
Generally, houses in northern climates are built with the water pipes located on the inside of the building insulation, which protects the pipes from subfreezing weather. However, extremely cold weather and holes in the building that allow a flow of cold air to come into contact with pipes can lead to freezing and bursting.
Water pipes in houses in southern climates often are more vulnerable to winter cold spells. The pipes are more likely to be located in unprotected areas outside of the building insulation, and homeowners tend to be less aware of freezing problems, which may occur only once or twice a season.
Pipes in attics, crawl spaces and outside walls are all vulnerable to freezing, especially if there are cracks or openings that allow cold, outside air to flow across the pipes. Research at the University of Illinois has shown that “wind chill,” the cooling effect of air and wind that causes the human body to lose heat, can play a major role in accelerating ice blockage, and thus bursting, in water pipes.
Holes in an outside wall where television, cable or telephone lines enter can provide access for cold air to reach pipes. The size of pipes and their composition (e.g., copper or PVC) have some bearing on how fast ice forms, but they are relatively minor factors in pipe bursting compared with the absence of heat, pipe insulation and exposure to a flow of subfreezing air.
When is it Cold Enough to Freeze?
When should homeowners be alert to the danger of freezing pipes? That depends, but in southern states and other areas where freezing weather is the exception rather than the rule (and where houses often do not provide adequate built-in protection), the “temperature alert threshold” is 20 degrees F.
This threshold is based upon research conducted by the Building Research Council at the University of Illinois. Field tests of residential water systems subjected to winter temperatures demonstrated that, for un-insulated pipes installed in an unconditioned attic, the onset of freezing occurred when the outside temperature fell to 20 degrees F or below.
This finding was supported by a survey of 71 plumbers practicing in southern states, in which the consensus was that burst-pipe problems began to appear when temperatures fell into the teens. However, freezing incidents can occur when the temperature remains above 20 degrees F. Pipes exposed to cold air (especially flowing air, as on a windy day) because of cracks in an outside wall or lack of insulation are vulnerable to freezing at temperatures above the threshold. However, the 20 degrees F “temperature alert threshold” should address the majority of potential burst-pipe incidents in southern states.
MITIGATING THE PROBLEM
Water freezes when heat in the water is transferred to subfreezing air. The best way to keep water in pipes from freezing is to slow or stop this transfer of heat.
Ideally, it is best not to expose water pipes to subfreezing temperatures, by placing them only in heated spaces and keeping them out of attics, crawl spaces and vulnerable outside walls. In new construction, proper placement can be designed into the building.
In existing houses, a plumber may be able to re route at-risk pipes to protected areas, although this may not be a practical solution. If the latter is the case, vulnerable pipes that are accessible should be fitted with insulation sleeves or wrapping (which slows the heat transfer), the more insulation the better. It is important not to leave gaps that expose the pipe to cold air. Hardware stores and home centers carry the necessary materials, usually in foam rubber or fiberglass sleeves. Better yet, plumbing supply stores and insulation dealers carry pipe sleeves that feature extra-thick insulation, as much as 1 or 2 inches thick. The added protection is worth the extra cost.
Cracks and holes in outside walls and foundations near water pipes should be sealed with caulking to keep cold wind away from the pipes. Kitchen and bathroom cabinets can keep warm inside air from reaching pipes under sinks and in adjacent outside walls. It’s a good idea to keep cabinet doors open during cold spells to let the warm air circulate around the pipes. Electric heating tapes and cables are available to run along pipes to keep the water from freezing. These must be used with extreme caution; follow the manufacturer’s instructions carefully to avoid the risk of fire, and check to make sure the product conforms to UL 2049. Tapes and cables with a built-in thermostat will turn heat on when needed. Tapes without a thermostat have to be plugged in each time heat is needed, and may be forgotten.
LETTING THE WATER RUN
Letting a faucet drip during extreme cold weather can prevent a pipe from bursting. It’s not that a small flow of water prevents freezing; this helps, but water can freeze even with a slow flow.
Rather, opening a faucet will provide relief from the excessive pressure that builds between the faucet and the ice blockage when freezing occurs. If there is no excessive water pressure, there is no burst pipe, even if the water inside the pipe freezes.
A dripping faucet wastes some water, so only pipes vulnerable to freezing (ones that run through an unheated or unprotected space) should be left with the water flowing. The drip can be very slight. Even the slowest drip at normal pressure will provide pressure relief when needed. Where both hot and cold lines serve a spigot, make sure each one contributes to the drip, since both are subjected to freezing. If the dripping stops, leave the faucet(s) open, since a pipe may have frozen and will still need pressure relief.
IF YOU SUSPECT A FROZEN PIPE
If you open a faucet and no water comes out, don’t take any chances. Call a plumber. If a water pipe bursts, turn off the water at the main shut-off valve (usually at the water meter or where the main line enters the house); leave the faucet(s) open until repairs are completed. Don’t try to thaw a frozen pipe with an open flame; as this will damage the pipe and may even start a building fire. You might be able to thaw a pipe with a hand-held hair dryer. Slowly apply heat, starting close to the faucet end of the pipe, with the faucet open. Work toward the coldest section. Don’t use electrical appliances while standing in water; you could get electrocuted.
GOING ON A TRIP
When away from the house for an extended period during the winter, be careful how much you lower the heat. A lower temperature may save on the heating bill, but there could be a disaster if a cold spell strikes and pipes that normally would be safe, freeze and burst.
A solution is to drain the water system. This is the best safeguard. With no water in the pipes, there is no freezing. This remedy should be considered even when the homeowner is not leaving but is concerned about a serious overnight freeze.
To drain the system, shut off the main valve and turn on every water fixture (both hot and cold lines) until water stops running. It’s not necessary to leave the fixtures open, since the system is filled mostly with air at that point and not subject to freezing. When returning to the house, turn on the main valve and let each fixture run until the pipes are full again.
WATER DAMAGE Claims DUE TO Freeze-Up and Burst Water Pipes
Compliments of the “polar vortex”, frigid temperatures in the Northeast and in the Southern States have caused many water pipes to freeze and burst. Residential and commercial properties have been affected. Pipe freeze-up and unfreezing damages were particularly severe in southern climates, where piping systems lack freeze protection more common in the north. Even in the Northeast, property owners saw (and continue to see) significant pipe failures. Most of the pipe bursts occur inside uninsulated and/or unheated janitor closets, basements, attics, exterior faucets/piping, and so on. In some cases, fire sprinkler systems froze, allowing fire to spread due to the lack of fire protection. Malls, restaurants and other walk-in retail establishments suffered business interruption, and some lost power as well as other utility services.
Most standard plumbing codes reference guidelines or standards in recognizing freezing of most buildings. Typically, they are as follows:
“A water, soil, or waste pipe shall not be installed or permitted outside of a building, or concealed in outside walls or in any space where they may be subjected to freezing temperature, unless adequate provision is made to protect them from freezing.”
In your evaluation and investigation of these types of cases, you should keep in mind the absolute cause of the freeze up and determine whether or not there are issues concerning coverage, liabilities, subrogation, and ultimately evaluate the damage to determine extent of damage and reasonable cost for repair or replacement of these items.
We had already assignments for a frozen pipe activating a sprinkler system which flooded the insured’s property. Both MSO and ISO policies contain general mitigation of damages provisions requiring insureds to take reasonable efforts to prevent further losses from occurring, such winterize the pipes in the home, maintain heat, etc.
Ex.: ISO Form HO 00 06 says:
We do not insure, however, for loss:
C Caused by:
(1) Freezing of a plumbing, heating, air conditioning or automatic fire protective sprinkler system or of a household appliance, or by discharge, leakage or overflow from within the system or appliance caused by freezing. This exclusion does not apply if you have used reasonable care to:
(a) Maintain heat in the building; or
(b) Shut off the water supply and drain all systems and appliances of water.
The insurance industry is presented with claims that surround freezing of water pipes that ultimately burst and result in property damage claims. There are many causes for these claims, some of which involve the following:
1. Improper maintenance of heat in a building or chase way (occupied or vacant).
2. Sudden shutdown of heating system, combined with improper inspection or maintaining of heat in a building.
3. Deterioration or lack of insulation protecting building and water piping.
4. Mechanical or electrical malfunction of a control or product.
5. Inadequate servicing and maintaining of piping, whether considered to be part of constant wet or water flow piping, and/or a dry pipe system, which normally does not allow constant water pressurization.
As the action or inaction of the insured is critical in determining whether coverage applies, a thorough examination of the circumstances of the loss is crucial: these claims are fact-sensitive and we can assist you in properly developing them.
Burst pipes, flooded basements, devastating structural damage, damaged floors, ceilings, carpets, wiring, furnishings, wallboard, and mold are a few obvious results of freeze up and pipe burst damage. These types of problems can result from maintenance problems, mechanical failure, installation errors, low temperatures maintained in buildings, or fuel delivery issues. Be sure to learn more about METROPOLITAN’s proprietary Fuel Usage Analysis Computer Program. This computer program compares data we retrieve with energy consumption levels to validate the results of our investigation.
Why do water pipes burst in winter?
The pipe bursts always in a longitudinal fashion. The burst always occurs at the weakest portion of the pipe. Because of its unique properties, water expands as it freezes into ice by as much as nine percent (9%) in volume. On the other hand, a metal pipe shrinks when frozen. In a pipe, ice forms first on the inside wall of the pipe and grows radially inward until there is a solid plug of ice blocking the pipe. Until that situation occurs, the expansion of the freezing water in the pipe merely pushes water back into the water main. When the plug of ice completely blocks the pipe, it seals water between the plug and a closed valve. If more ice forms between the plug and the closed valve, the expanding ice has nowhere to go, and causes the pipe to burst at its weakest point. Hot water pipes will burst much faster than the cold water pipes.
Pipe bursting occurs when
(1) Freezing temperatures create ice blockages in water pipes, then (2) Further ice growth applies dangerously high pressures to a confined water volume.
Most of the research and claims investigated by METROPOLITAN uncovers results that examine the effect upon the freezing process of five variables:
1. Design temperature.
2. Pipe composition, (copper or PVC).
3. Insulation level.
4. Pipe diameter ( 1/2” or 3/4”).
5. Water source (cold or hot water tap).
The Freezing events in a water pipe can be sub-divided into four distinct stages:
1. Initial cooling through super cooling.
2. Dendritic ice formation.
3. Annular ice formation.
4. Final cooling to ambient temperature.
Timetables for freezing temperatures can vary, but the testing performed by the University of Illinois confirms the following:
When a water pipe is exposed to subfreezing temperatures, heat is transferred from the water, through the pipe wall and any insulation layers to the sub-freezing air. The temperature of the water begins to fall in a steep decline. Remarkably, the water in the pipe does not immediately begin to freeze when it reaches the phase change temperature of zero degrees Celsius, but continues to fall and approach the temperature of the surrounding air.
In research tests water pipes placed in an unheated, insulated attic consistently started forming ice when the outdoor temperature dipped below 20 degrees Fahrenheit (20 degrees F). Importantly, the 20 degrees threshold is primarily for homes in the south and other areas where freezing may occur once or twice a winter or cold season.
In research tests water pipes placed in an unheated, insulated attic consistently started forming ice when the outdoor temperature dipped below 20 degrees Fahrenheit (20 degrees F). Importantly, the 20 degrees threshold is primarily for homes in the south and other areas where freezing may occur once or twice a winter or cold season.
This process is known as super cooling. It is possible for water in a pipe to super cool for a considerable length of time before any ice forms. The temperature at which ice begins to form is known as the ice nucleation temperature. The nucleation temperature implies a starting, or a nucleus, for ice formation. It is often claimed that, when subjected to identical conditions, a hot water line will burst before a cold water line. One theory states that premature bursting is the result of greater dendritic ice formation in hot water pipes than in cold water pipes.
However, testing of water drawn from both cold and hot water taps revealed that at the time of bursting, there was no difference if the water was drawn from a cold water source or a hot water source. Further research and investigation is required, but it is believed that a tendency for hot water pipes to burst before cold water pipes might be due to the distribution of entrapped air in residential water systems because of water heating processes. Clearly, you should be aware that the source of the freezing temperature could be the overall environment, a broken window, or uninsulated pipe exposed to the obvious temperatures. What occurs is an ice formation pattern in which there is the expansion of ice, or the growth of ice, through the pipe. As the pipe continues to freeze, particularly in a vertical situation, the frontier of the ice/water climbs in the pipe. At the same time annular ice against the pipe wall grows inward.
The Forensic Investigation
It is METROPOLITAN’s experience that there is no substitute for a thorough and comprehensive inspection of the structures to determine the number of conditions that caused the loss and whether the conditions worked independently, concurrently, or in a sequence to cause the damage. For example, some common questions include:
· Was the pipe frozen and burst due to lack of maintenance, wear and tear or incorrect installation? E.g., old or corroded pipes, or no proper insulation, etc.
· Was the frozen pipe damaged due to negligence? did the insured turn off the heat in the home or commercial property during cold weather?
· Did the boiler or furnace shutdown and caused the pipe freeze-up? Did the boiler or furnace had a mechanical breakdown or it was shut down by the insured? METROPOLITAN can reveal the causes of these failures utilizing mechanical evaluation of the boiler or furnace, perform a fuel usage analysis and perform an examination of the condition of the equipment installation. We can also determine the thermostat setting temperature, or whether the fuel run out, along with the timing of these events. METROPOLITAN will obtain a copy of the insured’s utility bill and will audit it for the purpose of making the above determinations. Our Energy and Fuel Usage Modeling will determine what really happened and determine the cause of the pipe burst.
· Was the pipe broken due to normal wear and tear?
A comprehensive investigation is crucial to good claims handling. It is vitally important to conduct bench testing of boiler controls and a Comprehensive Freeze Up Loss Investigation for freeze up losses. Courts have ruled against companies that have skimped on their investigations and rushed coverage decisions in these types of losses. Our clients require prompt and thorough claims investigation and fact finding and METROPOLITAN delivers high quality services at a highly competitive price.
It’s getting colder and with that cold comes the hassle of frozen / broken pipes, if you don’t take a few precautions. Here are a few winterizing tips that just might keep me from having to make a service call to your house.
Hose Bibs
#1 Disconnect all hoses from your hose bibs! Most hose bibs installed these days are frost free which shuts the water off inside the wall away from the outside cold but, if you do not disconnect the hose the water stays trapped in the spout. When the water freezes it expands and will damage the hose bib. This problem is usually discovered in the spring or summer when you turn on the bib for the first time and find water is coming out of your wall. Doing this will save you a costly repair.
#2 Hose bib covers. You can get these at any of your local home improvement stores. They are foam, dome shaped covers you put over your hose bib. These covers help keep the cold away from the hose bib. Hose bib covers are more important for non-frost free hose bibs but it wouldn’t hurt to put them an all of your outdoor faucets. Putting these on will also help to remind you to disconnect your hoses. These covers cost about 1-2 dollars and are a wise investment.
Insulate Piping
Many people often don’t realize the importance of insulating piping until it is too late and pipes are frozen and broken. All pipes in crawl spaces and any piping that is exposed on the outside of buildings or above the ground needs to be insulated. Pipes in garages that are not heated are also vulnerable to freezing in cold weather and should be insulated.
Pump Houses
All exposed piping in pump houses should be insulated. It is also important to have some heat in your pump house so your piping and pressure tank do not freeze. Your local home improvement store will have several different options for you to help keep your pump house warm and your pressure tank and piping from freezing. Items to look for or ask about are heat wire- this is wrapped around piping and warms up when plugged in. It keeps your pipes from freezing. Heat lamps can also be installed near your pressure tank and piping and will help keep your pressure tank and piping warm to protect from freezing. Both of these options can be plugged into a temperature sensing plug that turns on when it gets below a certain temperature and turns off when it gets above a higher temperature. These can also be purchased at your local home improvement store and are another great defense against broken pipes and expensive repairs.
How to keep pipes from freezing when temperature is going to drop below 32 degrees:
#1 Trickle water from a sink or two to keep water moving in your plumbing system, moving water takes longer to freeze than water that is not moving, this will help keep pipes from freezing.
#2 Open cabinet doors under sinks to allow warm air from the room to get back into the cabinet where pipes are.
#3 Turn your heat up a little warmer than normal. Warmer rooms mean warmer walls, and warmer walls help keep the pipes in those walls from freezing.
#4 Cover foundation vents around bathrooms, kitchens and laundry rooms that are on exterior walls to help keep the cold out and away from the piping in these areas. You can buy pre-formed Styrofoam blocks that fit in standard foundation vents at your local home improvement store. These covers should be removed when the risk of freezing is over in order to allow cross ventilation in crawl space areas.
#5 makes sure that all piping in attics and crawl spaces are covered with insulation. A lot of houses have blown in insulation in attics which is fine but it tends to settle and expose pipes. If you have blown in insulation inspect insulation to make sure it has not settled and exposed piping. Batt insulation is a better choice in my opinion.
How to keep this from happening again:
#1 Make sure that all piping in attics and crawl spaces are covered with insulation. We cannot stress this enough. This is where we saw most of the burst pipes we investigated. Most attics have blown in insulation and it settles over time exposing pipes. Exposed pipes freeze and burst.
#2 In older homes that contain copper or galvanized piping consider replacing with PEX piping. PEX piping may freeze but it resists breakage. In the 1000’s of investigations we have performed, not one break was PEX related. However, I did cut out 100’s of feet of copper and galvanized pipe and fittings.
Metropolitan Engineering, Consulting & Forensics (MECF)
Providing Competent, Expert and Objective Investigative Engineering and Consulting Services
P.O. Box 520
Tenafly, NJ 07670-0520
Tel.: (973) 897-8162
Fax: (973) 810-0440
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