Authors pickup truck in front of a winterized and frozen-in building in upstate New York (C) Daniel FriedmanBuilding Freeze Protection Methods
How to avoid ice, frost, freeze damage at & in buildings
Building plumbing & heating system frostproofing or winterizing procedures

  • POST a QUESTION or READ FAQs about how to protect buildings, piping, heating equipment, water softeners, wells, & foundations from freezing, ice, & frost damage

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Building winterizing or freeze-proofing guide: this article series provides step by step details in winterizing a building or freeze protection for buildings where heat may be lowered or left turned off. Avoiding freezing pipes in buildings also means avoiding later leaks, water damage, or possibly mold contamination.

The articles at this website will answer most questions about freeze protection for piping and other building plumbing and heating system components: how to winterize a building to avoid frozen pipes, and how to thaw frozen water supply & drain piping, wells, & water tanks.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

A Detailed Guide to Winterizing a Building to Protect from Frozen Pipes, Leaks, Water Damage

What happens when water freezes in a copper pipe?

Heating baseboard freeze damage leak (C) Daniel Friedman Frozen burst water supply pipe (C) Daniel Friedman

Our separated copper pipe solder joint (above left) shows how freeze damage to a heating system baseboard pipe can cause the copper pipe to simply slip apart at the solder joint. Our freeze-bulged and split copper water pipe (above right) shows how a copper water pipe can freeze, expand, and burst.

The resultant building water flooding and damage can be extensive and in some cases may involve a costly mold remediation project as well. Also, failure of an owner to take appropriate steps to prevent freezing pipes and water damage can result in loss of insurance coverage in some instances. For example, turning off heat without also winterizing a home would be an improper practice likely to lead to frozen burst pipes and water damage and mold contamination.

Our photo at left shows a separated solder joint caused by freezing at a heating baseboard copper pipe. The repair of this leak is shown later in this article.

Our page top photo shows a frozen, burst water pipe close to an elbow. We suspect that the process of heating the pipe during soldering of the elbow connection might soften the copper in this location, permitting the very rounded expansion shape at the point of pipe rupture. The elbow itself may be more resistant to bursting during freezing.

Details about the forces exerted by ice in or on buildings are at FREEZING FORCE of ICE.

Key Building Winterizing Topics to Avoid Freeze Damage

Burst water pipe under ground (C) Daniel Friedman

Freezing water pipes or drain pipes in a building are worse than inconvenient: often the frozen pipes burst, risking serious water damage and even toxic mold growth in a building when the frozen, burst pipe later thaws and leaks into the structure.

Our photo (left) shows what we found on arriving at an unoccupied home that was for sale in New York. Shortly after freezing conditions had lifted a water trail was visible running down the curb adjacent to the home. We thought perhaps there was a leak at that fire hydrant but that was not the problem. The water supply line beween the home and the curb had burst.

The most extreme water and mold damage to buildings where pipes burst occurs in unoccupied structures whose conditions are not being monitored, such as a house for sale, or a remote, weekend home.

Other freezing weather damage besides floods from frozen pipes can include cracked plaster in older homes or cracked and dislocated wood flooring.

For buildings facing these extra risks, we provide a range of suggestions for winterizing or freeze-proofing a building as well as for monitoring building conditions so that prompt action can be taken to deal with a burst pipe.

Here is our list of key topics to consider when working to winterize or freeze-proof a building, along with links to more detail on these subjects:

1. Prepare the building to be left unattended: regardless of whether heat is to be left on or off:

2. Decide if the building heat going to be left "on" or "off" : the answer determines the type and extent of freeze-proofing steps needed.

Winterizing Advice When Leaving a Building Unattended in Freezing Weather

Water spillage alarm (C) Daniel Friedman

Freeze Alarms: systems that warn of loss of heat or freezing conditions in a building can notify you or a building manager when something needs attention.

buildings with an existing security system can add freeze-alarms. If your building already has a security alarm system it's usually a small matter to add low-temperature, loss of heat, loss of electrical power, and water flood sensors to the system.

If your building does not already have a security system some simple devices can turn on a light to alert neighbors to a heat loss or building flood.

Freeze-damage risk points in buildings: where building piping, mechanical systems, or other components are likely to freeze. Identifying drafts and cold spots, sealing drafts, using insulation, or adding a little heat can prevent freezing.

Example of point of freeze risk in a building (C) Daniel Friedman

Our photo shows an example of a problem spot: piping under sinks in un-insulated pipe chases, piping in attics, crawl spaces, walls, garages, under floors.

Different piping materials (copper, steel, plastic) and different grades of water piping material affect the freeze-resistance of the piping. Installation details such as piping slope, routing, and insulation are important factors in pipe freeze problems.

We discuss the procedure for finding and protecting building freeze-points at Finding Freeze-Up Points.

Frozen hot water heating baseboards & radiators: how to prevent this problem which leads to loss of heat and more extensive freeze and later water damage to buildings. Our photo just shows a frozen, burst hot water baseboard heating pipe.

Frozen heating baseboard pipe (C) Daniel FriedmanIf a building heating system shuts down due to an operating problem (loss of electricity, a problem with the heater itself, or simply due to running out of oil) the heating system failure is likely to lead to frozen pipes which, when the weather warms, can cause serious building flooding and water or mold damage.

A burst heating baseboard line such as the ones we show here and at the top of this page can occur at more than one point in the heating system piping.

See our Heat-On Winterizing Guide.

PIPE FREEZE-UP POINTS, warns about burst building drains aswell as splits or separations in supply piping & heating system piping how to prevent freezing drain piping when water pipes area exposed to drafts or freezing temperatures.

Building drain clog (C) Daniel Friedman

Pipes run through a cold corner or subjected to drafts may freeze and burst even when some building areas are quite warm.

Watch out for for leaks and slow drips into drain systems. Even though you think the building is warm enough, slow water trickling down a shallow drain line outside of the building can build up enough ice to block the drain or even freeze and burst the drain pipe.

That is because a dripping faucet or a toilet that runs can send a slow trickle of water down a drain line through the heated building into an outdoor shallow drain exposed to freezing conditions and leading to freezing or even a burst drain pipe. These breaks also occur in an un-heated crawl space, basement.

Outdoor drain lines may be above the frost line and may be depending on proper slope to avoid retaining water that then freezes.

But a slow trickle or drip of water can still freeze in those locations and it can also flood a septic drainfield or soak pit.

Heat tapes & other heat sources to avoid frozen pipes: safely to avoid freezing pipes but also avoid fires.

Heat tape on a water pipe (C) Daniel Friedman

Using fans to move air, small point-source electric heaters or light bulbs, adding heat to crawl spaces, opening cabinet doors and similar steps can protect problem spots from freezing in a building when its temperatures are set low.

We discuss use of heating cables on plumbing supply and drain pipes at Heat Tape Guide.

We discuss where & how to add heat or insulation to prevent frozen pipes at Heat tapes, Heat, Insulation prevent Freeze-Up

Watch out: as we explain at Heat Tape Guide, some models of heat tapes used for freeze protection can cause a building fire if the tapes are not installed according to the manufacturer's recommendations, particularly if the tape crosses over itself.

As Ryan Duffy points out, connecting the heat tape to a GFCI-protected circuit can substantially reduce the risk of heat tape fires. However if the GFCI-protected heat tape circuit trips-off during typical current leakage conditions and without drawing attention of the building occupants, the risk of freeze damaged piping, leaks, water damage, and mold damage will be increased.

The US CPSC recommended in 1994 [PDF] that HUD consider dropping its no-GFCI-on-Heat-Tape-Circuit provision, and that heat tape powering electrical circuits be be protected with a GFCI device in the electrical panel rather than at the electrical receptacle or "outlet".

Ground fault protection was first required in the 1987 NEC for heat tapes that did not have a metal covering. In 1996/1999 the NEC expanded the requirements for GFCI protection and specified that mobile homes would have at least one heat tape receptacle. [A significant number of heat tape-related fires occurred in mobile and manufactured homes.]

Heating systems and their effect on building winterizing plans

Octopus warm air heating system (C) Daniel Friedman

Heating systems should be inspected and if necessary cleaned and tuned before leaving heat on in a building in order to assure that the heater is in reliable condition.

Heating boilers that are to be left turned on also need water supply left turned-on for both hydronic (hot water) and steam heat systems, but we outline a little plumbing trick will let you turn off all other water supply in a building.

Furnaces & electric heating systems do not need water to be left on in a building.

Hot water heat continuous circulation can be used in hydronic systems to reduce building freeze-ups. Steam heat system condensate returns need to be freeze-protected.

Heat-ON Winterization:
See WINTERIZE - HEAT ON PROCEDURE for a discussion of what to do to assure that your warm air furnace or hot water heating boiler or steam boiler will operate safely and reliably throughout the heating season.

Heat-OFF Winterization guidelines are

How to Protect Shallow Water Lines from Freezing

Reader Question: how can I prevent a too-shallow water line from freezing outside

I have an outside pump and tank attached to 50' 3/4" hose (buried in ground about 12")which draws water from a buried tank. The tank is deep enough to not freeze but my poor design does not allow me to drain the tank or the 50' length of hose with a foot valve at the end of it. What can I put down the line to prevent freezing like last year which blew up my hose. - Tony 10/13/2012

Reply: 4 tips on how to freezeproof a buried water that is too shallow for normal frost protection

Tony, I can think of several suggestions in escalating levels of trouble and detail

  1. Use compressed air: If the home is being shut down entirely you can try blowing all water out of the buried water line using compressed air; you'll have to make-shift some fittings to make it easy to send air through the buried water line from one end, leaving the other end open; even so this may not get all of the water out of the hose or water line but it may be enough.

    I converted a used A/C refrigerant gas canister that I pressurize either using a home tire inflator or at a gas station - taking care not to exceed the pressure ratings of the can (which could kill you). HVAC suppliers sell a kit that will convert the used canister to accept a schrader valve type tire inflator fitting that makes the job easier.

    A friend used this approach, forcing air back down a water supply line, to keep a water pick line from a lake from freezing in winter.
  2. Use RV type food-grade antifreeze: use a food-grade antifreeze intended for RVs, forcing it into the buried water line. Do not use automotive antifreeze which will first make you blind, then may be fatal.
  3. Excavate, insulate and install a suitable heating tape or wire along the pipe run. This approach requires that you trust elecrical power will remain on.
  4. Excavate, insulate, and install a heating loop in an insulated piping trench. Where rocky soils prevent getting a water pipe below grade it can be difficult to solve a freeze-up problem. An engineering friend, Stu Tucker designed, and I helped install an expensive freeze-proofing system for an uphill septic effluent piping system.

    Stuart's design included trenching around the existing buried piping, insulating the whole trench with solid foam insulation, and the installation of a small diameter fluid heater tubing loop that is connected to a tiny water heater.

    We filled that system with an antifreeze mix, added a timer, temperature sensor, and pump to circulate the heated antifreeze mixture through the trench. The system worked, though it was so expensive you wouldn't want to hire someone to do the project. This approach requires that you trust elecrical power will remain on.
  5. Excavate and bury the water line below the frost line. This may be the best approach in some areas, but in Northern Minnesota plumbers place outdoor lines six to eight feet below ground level for frost protection - it's not a trivial job.

Reader Question: can I add a recirculating pump to prevent heating zone pipes from freezing?

Question: 1/27/2014 Roni said: [posted originally at COLD HOT WATER RADIATOR or BASEBOARD ]

Have an Ultimate oil burner/boiler ( DHW coil removed), with 4 zones.
1st zone main floor, 2nd zone upstairs, 3rd zone sunroom addition, 4th zone Amtrol indirect HW maker


2nd heating zone piping freezes up with cold weather (usually below 20F).

Thermostat in master br must be kept at 59-60F otherwise other two bdr's get way too hot.(poorly designed loops for the pipes, too $$ to fix)


Is there a way to add a recirculating pump to keep a small flow of HW moving thru the 2nd zone even when the zone isn't "officially" calling for heat? Kinda like the idea where a pump is added to the furthest HW faucet in a home that keeps HW flowing so there's no need to run the water forever to finally have the HW reach the faucet.

Only other way to describe it would be for the 2nd zone valve to have variable flow-trickle to prevent pipe freeze and fully open when stat calls for heat. Crazy idea? Impossible solution?

Reply: adding a variable speed hot water heat circulator pump or an auxiliary circuilator pump or re-wiring for continuos water circulation


Yes there are several possible solutions:

  1. Turn up the thermostat: immediately pending other steps, keep the temperature high enough to avoid freezing - in your case 60F
  2. Set the circulator to run continuously: Assuming that your system runs with a single circulator and multiple zone valves, you can have your heating tech wire the circulator to run continuously.

    This is how homes in Canada are usually heated; it's custom in the U.S. to have the thermostat call for heat by turning on the circulator and the boiler temperature turn on the boiler via the aquastat. But in Canada the circs run all during the heating season (at least on many systems) and the TT is wired to turn on the heating boiler.
  3. You could install a variable speed circulator for the above application (see extra notes at 4. below)
  4. You could install a booster or extra circulator just on the freeze-prone zone. In this arrangement you would think you'd want to latch open the zone valve manually so that the circ could push water around, but you may have to also change the zone valve wiring to NOT call for heat - otherwise when the zone valve is manually latched open, its internal end-switch will also turn on the main circulator.

    In other words, you can convert the problem zone to one that is always circulating. If you install a variable speed circulator you can circulate water more slowly through that zone (or all zones) continuously. When the boiler temperature drops below the cut-in the boiler will cycle and provide heat.

    Alternatively if you disconnected the trouble zone's zone valve end switch wires (that normally turn on the main circulator), then latch the zone open, then add an additional variable speed circulator just for that zone, you'll circulate water more slowly.

How to Empty the Water Tank or Pressure Tank - Building Freeze Damage Protection

Question: How do we get water out of inaccessible water heater & water pressure tanks?

Horizontal water pressure tank (C) InspectaPedia

Concern: We have a crawlspace containing a hot water tank and pressure tank. The water supply is from our well. We need to close-up for the winter and need to let the water out. The crawlspace door is at other side of the cottage. Kinda far to crawl back and forth over hilly ground.

The crawlspace vents are screened. We almost bought a tube that is powered by a drill, to let the water out via hose, I believe it is called; a drill pump. I asked a nearby plumber and he said, take it back, may not work next year, etc. Also this plumber does the service for us, with a pump. Also a plumber will remove the sediment from the tank.

Our photo (above left) of a horizontal water pressure tank was provided courtesy of reader Doug Mehak.

We want to empty the hot water tank and pressure tank ourselves, have been doing so for over 35 years. This crawlspace is new, this year. My husband just emptied the other 02 house pipes, in case it got below zero this week, and water is everywhere. Next week, we will go to the cottage one more time and then close for the winter, any suggestions as to how we can empty the hot water tank and pressure tank, ourselves?

Cottage with crawlspace is in Haliburton, Ontario, Canada.

At least thanks for reading my concern, Ha Ha. - R.M., Ontario, Canada. 10/2/12

P.S. These are some solutions we are considering: --empty water by opening kitchen and bathroom faucets above, then only a bucket full will remain in hot water tank. take the bucket out with you and voila. (my husband says must mean city piping because we have a well) --just let the water go through dirt floor, in time will go through ground. (we are talking a 40 gallon tank, it will be muddy for a long time) --another hardware guy suggested, drain the water into a bucket or pail, creating a contained puddle, so to speak. then sump pump that water out.


A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem, such as noting the location, position of the problem water tank, what tappings on the tank are actually present and just where they are located, e.g. where there are only top tappings on the tank it may be possible to pump it out via a TP valve opening.

That said, thanks for writing with your own suggestions; on first reading your question, I hesitated in a prescription because lacking a clear description of the tanks involved, it appears that it not be possible to remove water from a water heater tank nor a water pressure tank located in an inaccessible crawl area.

While I'm not surprised at the description as often we find tanks squeezed into such areas, the installation does not sound correct, nor does it afford a means to empty the vessel; the result is not just a risk of freeze damage, but also other servicing cannot really be accomplished.

Watch out: water pressure tanks or hot water tanks in an inaccessible location are not only hard or expensive to service, repair, or replace, they may be unsafe - because the lack of ability to inspect the tanks means that safety devices such as temperature/pressure relief valves could be leaking or clogged - resulting in risk of a dangerous explosion. And of course a tank could be leaking into a hard-to-access crawl area for a long time before anyone discovers the problem.

The view that "only a bucket full will remain in hot water tank" does not sound reliable to me; the output from a water heater is delivered by the pressure of incoming water to the tank; if the tank has no drain whatsoever and we simply run water in the building with incoming water shut off (say by an inlet valve or by turning off a well pump) water is delivered only until the pressure in the whole system drops down close to zero (actual pressure depends on location and elevation of components). But the tank will still be full of water.

Watch out: I do not advise dumping water into a crawl area - it's asking for mold and insect problems.

Draining water pressure tanks and hot water tanks using the tank drain

Water pressure tank drain valve (C) DanieL Friedman

Usually both water pressure tanks and hot water tanks have a drain valve at the tank bottom.


and WATER HEATER FLUSH PROCEDURE for photos of those typical tank drains.

When the water tank or hot water tank is located in a below-grade basement or crawl space or any other location where it is not convenient to drain the tank by gravity using a garden hose, we attach a pony pump to the tank drain and pump the water out of the tank and over to a suitable drainage location.

Details about types of pony pumps (or transfer pumps) including both self-contained pumps and the drill powered transfer pump you mention, are given

Some bladderless water pressure tanks and some water tanks using an internal bladder can work in any position. Most water heater tanks are intended to work properly installed in an upright position, not jammed horizontally into a crawl space.

Watch out: if a water heater tank or water pressure tank that was designed to be installed in an upright position is installed horizontally the installation is improper, violates the manufacturer's installation instructions and warranty, may have a reduced life, will not work properly, and may be unsafe.

Emptying plumbing systems using compressed air

Some winterizing companies charged with emptying building tanks and pipes to prevent freeze damage open all pipes and drains to drain out what water they can (after shutting off incoming water of course), and then try blowing compressed air through the system.

While this helps move water out of pipes and might push some water out of water tanks or water heater tanks, I have not found this a completely reliable approach. Air can move through water pipes or tanks while leaving water behind, more so for piping that is not straight and pitched and still more so for tanks and vessels. Nevertheless, it's a useful step that reduces water in the system even it it can't completely eliminate it.

Emptying plumbing by cutting pipes

Professionals will also actually cut pipes if necessary to assure the piping system is drained fully, figuring that it's much less expensive to later repair the cut than to repair burst pipes in unexpected locations and to clean up and repair water damage to a building left unattended.

How to empty a water pressure tank

or water heater tank using a pony pump or a drill pump

Pony pump about to be used to service a heating boiler (C) Daniel Friedman

I agree that based just on the description provided, the most effective means of getting most of the water out of the tank in this circumstance would be to use an available tapping on the upper tank to insert a tube and use a pony pump or drill pump to pump water out of the tank, through a hose, to outdoors or to a nearby drain.

When circumstances demand tank replacement or when there is an opportunity for any other reason, I'd either relocate these tanks to an accessible area or provide easier access (in one such case we made an openable floor panel).

Our photo (left) shows our little pony pump at a job where we used it to empty a water heater tank through a garden hose to an outdoor location. Here I had not yet hooked up the pump but you can see the white pump body and the washing machine hose needed to hook it up to a tank drain.
See PUMPS, PONY PUMPS for details.

This pony pump use procedure is described at DEBRIS in WATER SUPPLY, Water Heater

Other examples of of use of a pony pump are


How to Empty Well Piping or Prevent Well Pipe Freeze-ups When Winterizing a Building

Reader Question: When draining water for winterizing, how do we get water out of the well, well piping, and submersible well pump?

When draining the water from a dwelling that is allowed to freeze, how does the water supply from the submersible pump, supplied with foot valve, drain so the at or above grade pipes don't freeze and break? - Nate, 10/12/11


Great question, Nate. There are two approaches to preventing water lines between the building and the upper part of piping inside the well from freezing

1. Well water supply outdoor pipes
 are buried below the frost line, including well piping from the point of exit of the well up to the building.

That's why at many older wells the well casing head was down in a "pit" - to protect it from freezing. Later the invention of the pitless adapter provided a fitting that permits the well piping to exit out of the side of the well casing below ground without leaking ground water into the casing at that point. That permits well casing tops to be brought up to above ground for improved sanitation.

2. On some wells that use both a submersible pum
p and a bladderless water pressure tank, a snifter valve allows air to enter the well piping from inside the building near the water pressure tank. To drain water out of the well piping inside the well a second drain fitting is installed in a tee in the well piping.

Search InspectAPedia for "Snifter Valve" and you'll find our details about this approach.

3. A third approach that is not commonly used but that I participated in installing was designed by IBM Engineer Stu Tucker for his home at Lake George NY. The home draws its drinking water right from the lake. Normally homes in that area pull the well piping out of the lake in winter to avoid freezing.

Stu designed a system that pumps air from the water pressure tank back out the incoming water line at sufficient pressure that he could be confident that the water in the well piping was pushed backwards out of the pick-up strainer and into the lake to a depth that placed air into the well piping even in the lake to a depth below the lake freeze-over point.

The system was not as complicated as one might think. It amounted to an overcharge of air in the pressure tank and use of a submersible pump that is in the lake (so there is no issue with loss of prime).

Reader followup:

well with pitless adapter. I'm only concerned with the piping, inside the building, that is above frost level. I need to know if it will drain over a certain amount of time, or if I need to insert a tube and pump out the supply tubing to a level below frost line. Thanks - Nate


Nate if your well pipes are NOT below frost line (option 1) the answer is that you need to determine if you have a snifter valve and in-well drain or not (option 2). If you don't, you'll need to use approach like #3 below or your own suggestion.

How to Winterize a building to Prevent Freeze Damage

First we decide the level of building winterization to be undertaken. There are two very different approaches to protecting a building and its mechanical systems from freezing-damage:

  1. Heat-on winterization: the first approach to winterizing a building involves keeping the building heated, but to a lower temperature. This approach is usually best for a building as it helps avoid indoor humidity, moisture, and even freeze-cracking of some building materials such as flooring or drywall. We discuss "Heat-On" building winterization steps

  2. Heat-off winterization: the second approach to winterizing a building is to turn off its heat, often also its electricity, drain piping, and take other steps to reduce the chances of freeze-damage.

    This approach is taken when a building is to be left unoccupied for a long time, when the owners cannot pay for heat (though they may face later repairs that would have made the heating cost look attractive), or when a building has been abandoned, such as a foreclosed property. We discuss "Heat-Off" building winterization steps


Building Freeze Protection Articles


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