Winterizing Guide: How to Freeze-Protect Water Supply Piping, Drain Piping, Water Pumps, Tanks, Heaters - Turning HEAT OFF
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How to winterize or freezeproof a building - how to winterize when you plan to turn HEAT OFF
How to avoid freezing water supply pipes and drain piping, drains, traps, toilets, etc.
How to winterize pipes: frost protection for plumbing systems
How to shut down a buildings water, heat, and other components to prevent freezing or water, mold and related damage
Questions & Answers about winterizing a building with heat off and drained pipes

This article explains how to winterize or freeze proof a building when the building's heating system is going to be turned off completely.

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We discuss turning off water supply, draining piping and plumbing fixtures, turning off and if necessary winterizing a heating system, and other steps to avoid freeze damage or water, leaks, and mold damage to buildings that are being left in a "shut down" condition. 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.

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Is the building heat going to be left "on" or "off" - the answer determines the extent of freeze-proofing needed.

If heat is to be left on in a partially winterized building see the procedure at: Winterize - Heat On
If heat is to be turned off and the building completely winterized, see the procedure at: Winterize- Heat Off (continuing just below)

How to Winterize a Building If you are Turning the Heat Off

If you have decided to shut down the building's heating system, some steps to protect the building from freeze damage are simple (you don't worry about figuring out the thermostat set-temperature nor about finding "cold spots" where pipes may freeze). But other critical steps need to be performed:

Close the main building water supply valve. Check that the valve really closed fully during the process of draining the piping. Be careful: some valves that are seldom used or which are old may not close off completely. You just think you've turned off the water supply, but really your water main valve may still be slowly feeding water back into the supply piping. Details on how to find and use water shutoff valves is at WATER SHUTOFF VALVE LOCATION, USE.
If a water pump and pressure tank are installed, turn off electrical power to the water pump. (Draining the pump and water tank are discussed below.)
Drain the building water supply piping; because most homes other than some vacation cottages are not built with piping intended to be periodically drained, there may be long horizontal pipe runs that will not easily drain out all of their water by gravity, or even some supply pipes that slope "backwards" and refuse to drain.
1. Use air to remove water: Some plumbers try blowing air through the piping to force out water, or they may install multiple points at which piping can be drained. Below we address some steps to check for frozen, burst piping when turning the water supply back on.
2. Cut pipes to remove water: Other plumbers will simply cut open any water supply pipe that may not be draining properly, figuring that it's a much smaller repair to later close that cut connection than to fix a building that has been flooded.
3. Use the building drain: Most buildings include a building drain valve located at or near the lowest point in the building supply piping, but "inside" the building or past the main building water supply shutoff valve.
Drain the building plumbing fixtures, tanks, faucets, such as

Winterize toilets, and remove all toilet water from bowls and toilet tanks. Some winterizing companies pour an anti-freeze mix into building toilets and traps. Some anti-freeze chemicals are toxic and should not be discharged into a septic system. See notes below about use of antifreeze in buildings.
Winterize water heaters (never turn on electricity to a drained electric water heater, nor turn on power to a gas or oil fired water heater either - it is dangerous and is likely to destroy the heater too)
Winterize well water tanks and pumps: need to be completely drained of water - a frozen burst in-building water pump adds an expensive repair later
Winterize all building faucets: after water supply has been turned off, open every faucet and leave it open - water left in a faucet can freeze and break it.
Open outdoor faucets: be sure also to remove any garden hoses on outside faucets. A garden hose can retain water that freezes and damages the outdoor hose bib (faucet).
Winterize the building supply piping: above we recommended removing all water from the supply pipes, cutting pipes if necessary.

To be sure that you have not left water in a hidden corner of supply piping somewhere, if you have not done so, see our tips at Find & Fix Water Pipe Freeze-Up Points which was discussed under the "heat-on" winterization notes.

If your incoming municipal water supply piping is not well below the frost line it may be necessary to find or even install a water shutoff valve closer to the connection of your building's water piping to the municipal water main. Private water supply systems are easier to shut down but also need to be drained.

Turn off and drain the water softener or other water treatment equipment.

See details at Winterize Water Softener & Treatment Equipment.

TThis article explains water softener shut-down procedure, explain why we use the water softener bypass valve, and how that can reduce the risk of freeze damaged pipes, leaks, and even indoor mold growth.

A separate article Restoring Water Softener & Treatment Equipment provides details on returning a shut-down water softener to operation after it has been shut down.

Winterize all building drains: if you have not already done so, review our tips at Freeze Protect Drains which was discussed under the "heat-on" winterization notes. Further steps include removing traps and use of a non-toxic antifreeze in traps or toilets that cannot easily be removed or emptied of all water.

Empty or remove building fixture traps; see our note below about use of antifreeze.

Use of antifreeze to winterize a building: Be careful: unless the anti-freeze is specifically designed for winterizing a building it could be highly toxic (such as automobile antifreeze).

We do not recommend using toxic antifreeze to winterize a building since later you're moving that contaminant into the public sewer or into soils (and possibly ground water) around a private septic system. Only inside of closed water systems such as a heating boiler do we recommend use of anti-freeze mix in a building.

Drain the hot water tank and other building tanks: the hot water tank and water pressure tank and pump itself if a private well and tank system are installed.

This sketch of a gas-fired water heater and its control valves is provided courtesy of Carson Dunlop.

Warning: do not drain a water heater tank before first turning off its energy source: oil, gas, or electricity.

Heating an empty water tank is very dangerous and is likely to quickly destroy the tank or its heating elements.

Also see Winterize Water Softener & Treatment Equip. - about turning off water softeners and, if heat is to be turned off, drain the softener and any other water treatment equipment.

Shut down the heating system when all other steps to protect the building have been completed:
- Hot water heating systems: Drain the building heating boiler and heating supply piping, or install an anti-freeze mix in the heating boiler and its supply piping. Notify your oil heat supplier if you are turning off heat in the building, and remember to notify them again when it is turned back on.
- Steam heating systems: drain the heating boiler and condensate lines and condensate pump if a pump or pumping station are used.
- Electric heat or warm air furnaces: can simply be turned off.

Questions & Answers about winterizing a building with heat off and drained pipes

Question: How can we test for possible foundation damage if we leave our home with heat off completely?

We built our home 15 years ago. It is a split level with concrete foundation. When we retired we stated to spend our winters in a warmer climate (we live in N. Ontario). Every winter we have left some heat on the lower level of the house keeping the temperature around 4c.

However with the increase in the cost of oil and our dwindling income buying power, we have been thinking of ways we could cut off both the hydro and the oil heater. Is there any way of us testing what effect this might have on the concrete foundations?

The foundation is covered with a layer of ceramic tiles which we later covered over with a laminate flooring. Thank you. - C.W., northern Ontario

Our sketch (left, courtesy of Carson Dunlop Associates) shows what happens when a home is left with heat off in a freezing climate.

Reply: Tests for possible frost damage to foundations? try these local research topics

I don't know of an actual test that you can perform to predict foundation damage if the heat is left off completely in your building, since testing would require creating the actual freezing conditions and would itself risk building damage. Sketch at left, showing evidence of frost heaving is provided courtesy of Carson Dunlop Associates.

At "A Common Source of Vertical Frost Heave - Un-heated Homes" found in our article VERTICAL MOVEMENT IN FOUNDATIONS we discuss the problem of foundation damage in un-heated homes. And at Frost Heave/Expansive Soil Cracks in Slabs we provide more details.

Sketch (left, courtesy of Carson Dunlop Associates) shows upwards as well as horizontal frost pressure on a building and it indicates where cracks and dislocation commonly appear.

Here are some things you can check:

Where is the home located? In northern Ontario your home is not at the same level of risk as the far north, but we agree that frost damage is a real risk.
How is the home constructed? In those same extreme climates builders use a floating slab design or other methods intended to avoid differential heaving or settlement of the structure.
How deep are your foundation footings and basement or crawl space slabs? If the footings and slabs are well below the frost line (which should be the case) then frost heaving of the slab or footings should not be a significant risk.
Is there exterior foundation insulation installed? Foam foundation insulation on the building exterior increases resistance to frost damage. See BUCKLED FOUNDATIONS due to INSULATION? for a discussion of the role of foundation damage and foundation insulation on the interior side of the building foundation walls

Is there already evidence of frost cracking, heaving, or damage to the building foundation walls, footings, or floor slabs? (See our photo at left). If so you can figure that with heat off this damage will increase. See Frost Heave/Expansive Soil Cracks in Slabs also see HORIZONTAL MOVEMENT IN FOUNDATIONS (horizontal frost push, for example) and see VERTICAL MOVEMENT IN FOUNDATIONS (frost heave, for example).
Are any neighboring homes suffering frost heaves or damage? Ask your neighbors who live in similar construction and on similar soils what their experience has been.
Check with local building officials. Your building department may have someone whose experience can shed light on the risk of frost damage to homes in your area.
Check with local foundation repair companies. As with building officials, local foundation repair companies or masonry contractors will be experienced with frost damage to homes in your area.

Watch out: other factors can still cause slab or foundation damage due to frost.

Wet soils around the home convert to ice and cause higher amounts of soil movement during freezing.
Ice lensing - sticking of wet soils to the foundation walls [Ice Lenses, Frost Heaves vs. Frozen Soil Pressure] - can cause frost heaves and foundation damage even if the bottom of the foundation and all slabs are well below the frost line.

Well drained soils and good roof drainage that keeps water well away from the building reduce these risks.

Other Steps to Reduce the Cost of Heating Left On to Avoid Frost Damage

An alternative to turning heat off in the building entirely is to continue your practice of leaving heat on at a low setting (4 C or about 40 F) but take measures to protect the building from damage (possibly allowing a slightly lower heat setting) and to reduce heating cost by finding and fixing drafts, air leaks, or by improving building insulation.

See Winterize - Heat On Procedure and the topics listed there.

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FREEZE-PROOF A BUILDING
Key Winterizing Topics
How to Winterize a Building

Winterize - Heat On Procedure
  Thermostat Settings
  Turn Water Off ?
  Winterize Water Softener & Treatment Equip.
  Find & Fix Water Pipe Freeze-Up Points
  Freeze Protect Drains

Winterize- Heat Off Procedure

De-Winterized a Building
  Thawing Frozen Pipes
  Repairing Burst Leaky Pipes
  Turning on Heating
  Restoring Drains
  Turning on Water
  Water Supply/Drain Pipe Leak Types
  Restoring Water Softener & Treatment Equip

"New Electric Heat Tapes Help Prevent Fires," US Consumer Product Safety Commission (CPSC) #00936
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
"Freezeproof Your House," Mike McClintock, Rodale's New Shelter, p. 30, October 1985 (approximate date)
"How to Winterize Your Pipes," Mike McClintock, Homeowners How-To Magazine, p. 59-62, Nov-Dec 1979.

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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ^® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.

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How to Winterize a Building If you are Turning the Heat Off

Questions & Answers about winterizing a building with heat off and drained pipes

Question: How can we test for possible foundation damage if we leave our home with heat off completely?

Reply: Tests for possible frost damage to foundations? try these local research topics

Other Steps to Reduce the Cost of Heating Left On to Avoid Frost Damage

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair