Avoiding the Deep Freeze - Insulation Outlook Magazine (2023)

We insulate surfaces for many reasons. The most common include energy savings, personal protection and condensation prevention, along with protecting the environment from greenhouse gases and the deterioration of the ozone layer. Every fall, many people insulate surfaces, primarily pipes, to prevent them from freezing.

Much of this insulation is sold through the do-it-yourself centers. Using insulation to save energy or for personal protection is a fairly very straightforward and common sense concept. However, calculating the correct thickness to prevent condensation is a more complicated proposition because additional environmental factors such as relative humidity and wind speed play a major role in selecting the correct thickness. These added environmental variables are often unknown or vary widely. This is also true when it comes to determining the correct thickness to prevent pipes from freezing in cold weather. As we will see, if the temperature is below freezing for an extended period of time, pipes with no water flowing through them will freeze unless a heat tape is applied to compensate for heat loss. Insulation can prolong the time before pipes freeze, but not prevent it in all cases.

This paper is divided into two sections. First we will look at the effects variables such as ambient temperature, pipe size, fluid temperature and insulation thickness have on the time it takes for pipes to reach freezing temperatures. Second, we will look at some of the variables used to select the correct heat tape/trace for a given condition.

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The concept of freeze protection is quite simple-use insulation to maintain the temperature of the fluid in the pipe above the freezing point (32 degrees fahrenheit [F]). Insulation thickness certainly plays a factor in this concept, as increased insulation retards heat flow. Ambient air temperature plays a major role. The lower the ambient temperature (greater temperature differential) the faster heat will be drawn from the residual heat in the fluid in the pipe. Pipe size and fluid temperature play a factor because each effects the amount of residual heat found in the pipe.

Effect of Variables When Considering Freeze Protection

The charts at top left (figures 1, 2 and 3) show the effects of variables when considering freeze protection. These include ambient temperatures, pipe size and fluid temperature.

Other considerations include pipe material and wind speed. Pipe manufactured from PVC provides some added time to freeze because it has a lower k factor than copper. However, there are other factors to be considered when considering PVC versus copper pipe from a material point of view, such as burst strength, and the ability to thaw or repair pipes. Wind speed will tend to slightly decrease the time to reach freezing.

The main difficulty in determining the correct thickness to prevent freezing is the time and ambient temperature factors. It’s often difficult to determine how cold an unheated crawl space, attic or outside wall will get when the temperature drops below freezing. Suffice it to say, if the temperature is low enough for a long period of time, the pipes will freeze without added heat input from either fluid movement (running water) or use of a heat tape/trace with sufficient Btu input to compensate for the Btu loss.

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Using insulation by itself to prevent frozen pipes can be recommended in the "southern frost belt" area of the southeastern United States, where temperatures only drop below freezing for short periods of time during the night, while during the day the pipes will have fluid movement. In the northern regions of the United States, where freezing temperatures set in for prolonged periods of time, it’s recommended that a heat tape/trace be used in conjunction with insulation.

When insulating pipes, it’s important to insulate all exposed surfaces, including tees, valves or faucets. Exposed surfaces may cause localized freezing.

Flexible closed cell polyethylene or elastomeric insulation are often used for the purpose of insulating plumbing, both residential and commercial. These lines could be found in crawl spaces, walls, attics or piping in parking garages. Fire sprinkler lines are often insulated as well as in unheated warehouses. The closed cell polyethylene is well suited for these types of applications because of its excellent range of properties (low thermal conductivity and water vapor permeability) and ease of installation (no need for additional water vapor barrier).

Selection of a Heat Tape/Trace

Heat tapes/trace systems have come a long way in the past several years in terms of performance and ease of installation. It’s highly recommended to insulate lines that are heat traced to improve the performance of the heating cables.

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The first step in selecting a heat trace system is to match the application and the environmental conditions with the correct heating cable power output. Selection guides are available from the manufacturers of the heating cables for this purpose. Criteria that will have a determining factor on the system selected will be pipe location, pipe size, pipe material, minimum expected ambient temperature, temperature at which the pipe is to be maintained, length of run and the type and thickness of applied insulation. Systems are available for freeze protection (above and below ground) along with flow maintenance applications such as grease or fuel lines. The heat loss through the insulation wall must be balanced with the heat gain provided by the heat trace tape. This balance will prevent the system temperature from escalating above the recommended use temperature for the insulation.

Depending on the application, you may choose a standard outer jacket on the heating cables or a more chemical resistant jacket for industrial applications. The heating cable length depends on the length of the run and the additional footage that may be needed to protect valves, flanges and pipe supports. These areas of high heat loss may require additional footage. In addition, extra cable will be needed for power connections, tees and end seals.

For added power output, higher voltage lines or additional cable strips may be run together. Again, the concept is to balance the heat input with the heat loss, and the type and amount of insulation used will effect this calculation. Typical heat trace tape wattages (per lineal foot) are typically available in 3, 5, 8 and 10 Watt products where 1 Watt = 3.412 Btu/hr.

Cables are designed for easy connections. Most heating cables are now self regulating in terms of temperature control that varies its power output to respond to temperature all along its length. This allows the cable to be cut to length in the field and it saves energy.

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Heating cable systems can be controlled either manually, by thermostatic control or self-regulating. All heating cables should be Underwriters Laboratory (UL) Listed, Canadian Standards Approval (CSA) certified, or Factory Mutual (FM) approved for their use. The most common thickness for heat trace tape is 1/4 inch, and will require that the insulation inside diameter is sized properly to fit over both the pipe and the tape. If this isn’t taken into consideration, the longitudinal seam could experience excessive stress. Normally, because of insulation’s flexibility, no adverse effects are to be expected.

Heat Trace Cable System Recommended for Long Term Cold Conditions

Application of insulation will provide protection to pipes from freezing under short term cold conditions. For longer-term conditions, the use of a heat trace cable system is recommended in conjunction with insulation. Flexible closed cell insulation based on polyethylene resin is often used for this purpose because of its performance properties and ease of installation. The use of an insulated heat cable system provides a simple and reliable method to prevent frozen pipes in even the most severe conditions. Today’s heating cable systems have a number of benefits. They have the ability to be overlapped, and there’s no need for a thermostat. Also, they’re designed for energy savings and to eliminate overheating or burnouts.

Figure 1

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Figure 2

Figure 3


Will spray foam keep pipes from freezing? ›

In addition to keeping your pipes from freezing this winter, spray foam insulation can reduce the overall draftiness in your home and keep the entire area warmer during the cold winter months.

What is the best insulation to stop pipes from freezing? ›

Use foam rubber or fiberglass sleeves to help decrease the chances of freezing. Insulation can help keep the pipes closer to the temperature of the water inside the pipe, but it does not add extra heat to the pipe and unfortunately will not prevent freezing if the pipe is exposed to prolonged freezing temperatures.

How much insulation is needed to keep pipes from freezing? ›

Surround the pipes on all four sides with 2-inch rigid insulation, then create an inlet and an outlet for warm air at each end of the chase. Keep air flowing with a small duct fan.

Does insulation prevent freezing? ›

Insulating your pipes and water tanks is one of the best ways to prevent them from freezing.

How do I keep my pipes from freezing overnight? ›

If cold weather's on the way, it's worth taking some simple steps to prevent your pipes from freezing:
  1. Insulate pipes and water tanks. Wrap pipes in cold areas with pipe sponge covers. ...
  2. Leave your heating on. ...
  3. Open cabinet doors and loft hatches. ...
  4. Run your taps. ...
  5. Drain your water system.

Should you spray foam around plumbing? ›

Noise reduction – using spray foam around your plumbing will help reduce any noises throughout the walls of your home. As a natural insulator, the spray foam keeps your pipes from knocking or even controls the noise of vibration created by the flow of water through your copper or PVC pipes.

Is rubber pipe insulation better than foam? ›

A safe conclusion when comparing rubber versus foam plastic pipe insulation is that rubber is the better choice for commercial and industrial applications due to its lower thermal conductivity, higher continuous operating temperature, and more predictable fire behavior.

Will pipes freeze in an insulated wall? ›

If temperatures get low enough, like we are used to seeing at least a few times during a typical Michigan winter, pipes can certainly still freeze even if they're really encased in insulation. If there's no heat source that's able to get to the pipe, you always run that risk.

At what temperature do pipes freeze in crawl space? ›

So what temperature do pipes freeze, and how can you keep it from happening? Pipes are at risk of freezing when temperatures drop below 32 degrees Fahrenheit, but they most commonly freeze at temperatures of 20 degrees and below.

Will pipes freeze at 32 degrees? ›

If the temperature falls to 32 degrees or lower, your pipes are likely to freeze.

How long does it take pipes to freeze at 28 degrees? ›

The rule of the thumb is that it takes roughly 6-hours for water in your pipe to freeze after left in an unheated area.

Can pipes freeze in one night? ›

Pipes can freeze in as little as six to eight hours, meaning they can freeze overnight. If the outside temperature is below 32 degrees F and your pipes are unprotected, your chances for a frozen pipe increase.

What is the best insulation for outside pipes? ›

EPDM rubber insulation is ideal for outdoor, high temperature and solar pipework use.

What do you wrap pipes with to keep them from freezing? ›

Wrap pipes with heat tape or thermostatically controlled heat cables. Be sure to follow all manufacturers' installation and operation instructions. Seal leaks that allow cold air inside, near where pipes are located (i.e. around electrical wiring, dryer vents, other pipes), with caulk or insulation.

What temperature should I leave my house so pipes don't freeze? ›

Here's a list of ways to prevent freezing pipes in your home: Keep the thermostat at a minimum of 68 degrees Fahrenheit. Make sure pipes are properly insulated. Keep water slowly flowing on outer wall faucets.

What temperature should I stop my pipes from freezing at night? ›

A consistent temperature in your home is arguably the best way to stop pipes from freezing and bursting. While most people switch off their heating at night, keeping your thermostat set at around 12 or 13 degrees can maintain a consistent level of heat and stop your pipes from getting too cold.

Which pipes are most likely to freeze? ›

Pipes that freeze most frequently are: Pipes that are exposed to severe cold, like outdoor hose bibs, swimming pool supply lines, and water sprinkler lines.

When should you not use spray foam insulation? ›

Spray foam insulation of any type should not be applied to a substrate or in an air temperature above 120 degrees Fahrenheit. In storage, you also want to keep your spray foam insulation at least 3 inches from any heat source.

Can water penetrate spray foam insulation? ›

Moisture Barrier

Open cell spray foam is not a moisture vapor barrier, and will allow moisture to pass. So, if you're considering spraying foam to the roof deck of your new or existing home, you want open cell. If there's a roof leak, water will pass through the foam, and you will quickly be able to find your problem.

Do plumbers use expanding foam? ›

Moisture curing, polyurethane expanding foam, specifically developed for filling gaps around pipes and other plumbing applications. Adheres to most sanitary and plumbing materials; PVC, CPVC, copper, cast iron, chromed copper and chromed brass. Resistant to water, heat and ageing.

Does bubble wrap make good pipe insulation? ›

Pipe wrap foam is great for insulating exposed pipes during the winter. But if you don't have what you need on hand and you see a place you missed, try using bubble wrap. You easily can wrap it around most pipes, and it works pretty well.

Does pipe insulation need to be tight? ›

Secure the opening using duct tape. If you require more than one length, use duct tape to seal the joints. Finally, secure all insulation at 5 to 6 foot intervals with duct tape to be sure it stays on tight.

What is the best material to wrap pipes? ›

Use a “pipe sleeve” or similar insulating material on exposed water pipes. Newspapers can provide some degree of insulation and protection to exposed pipes – even one-fourth inch of newspaper can provide significant protection in areas that usually do not have frequent or prolonged temperatures below freezing.

How do plumbers unfreeze pipes in walls? ›

If the pipes are frozen but have not burst, a plumber can remedy them by applying a heat gun to thaw them. For an interim solution, a homeowner could use a hair dryer to start the thawing process. A plumber's main role and concern in this situation is to identify and fix the problem that caused the pipes to freeze.

Should I leave my attic door open during a freeze? ›

You don't want to leave the hatch to an attic open because all your heated air will get sucked into the attic. But it's a good idea to leave the doors open below a sink if you worry those pipes could freeze.

Should I put insulation on frozen pipes? ›

Insulating your water pipes is great way to prevent frozen pipes when the temperatures drop in the winter months. Even in more moderate climates, when freezing temperatures are infrequent, pipe insulation can help limit heat loss and condensation as water travels through your plumbing.

What is the coldest house temp before pipes freeze? ›

What temperature do pipes freeze in a house? We all know that freezing begins at 32° F or 0° C, but at what point do pipes freeze within our own homes? Temperatures only need to drop to about 20° F for a few hours to put exposed pipes at risk.

Will PEX pipe freeze in crawl space? ›

They are NOT freeze-proof. They can still break under extremely cold temperatures, but you can prevent this from happening.

Will space heaters keep pipes from freezing? ›

Use Space Heaters

If parts of your home have pipes and are unheated, electric space heaters can be used to keep the water in the pipes from freezing. You don't need to keep the area 70 degrees. Anything above freezing will do.

How long does it take for pipes to freeze at 31 degrees? ›

Pipes can freeze at 32 degrees or below, but it will take a sustained period of time for this to happen. In other words, a pipe needs to be at freezing temperatures for at least half a day before homeowners have to worry about any freezing occurring.

How long does it take water to freeze in pipes at 32? ›

With this in mind, expect most pipes to freeze within six to eight hours. Uninsulated exterior pipes can freeze in under six hours if the temperature is below 20 degrees. It takes at least 12 hours for unprotected pipes to freeze at 32 degrees.

Will pipes freeze in unheated basement? ›

The pipes most at risk are those in unheated interior spaces such as basements, attics, and garages. But even pipes running through cabinets or exterior walls can freeze.

Will PVC pipe freeze underground? ›

For PVC piping systems that are buried underground, sunlight won't be a problem, but debris, soil movement, and freezing temperatures may be. The debris and rocks that are underground with your pipes can lead to friction, which can cause damage to PVC pipes.

How long should heating be on to stop pipes freezing? ›

It is recommended to leave the heating permanently on to maintain a minimum temperature of 13 degrees C. If your boiler runs on oil or LPG gas, ensure that you have enough fuel to heat your property over winter. You don't want to run out and find your supplier is unable to deliver due to severe winter weather.

At what temperature does copper pipe freeze? ›

Copper pipes can freeze when temperatures drop below 20 degrees F. Copper is the most likely to freeze out of all the piping materials.

Can pool noodles be used for pipe insulation? ›

With clamp noodles, you can easily use the pool toys to insulate your pipes. These noodles wrap effortlessly around pipes and act as additional insulation. Most will fit seamlessly into the center of the pool noodle, and if there is a gap, you can use duct tape to close it.

Can you put heat tape over pipe insulation? ›

Install heat tapes on exterior surfaces and exposed pipes, not inside walls, floors or ceilings. Apply them directly on the pipe you want to protect from freezing, not around pipe insulation. * To avoid overheating, don't cover heat tapes with insulation, even though some manufacturers may permit it.

Should PEX hot water pipes be insulated? ›

The general rule of thumb: you do not need to insulate your PEX piping if it is passing through interior walls or insulated external walls. However, if you reside in a region with cold winters, you should insulate any exposed pipe that is outside or inside of unheated places like a basement, crawl space, or attic.

Should I leave heating on all night in freezing weather? ›

Remember, the higher the thermostat, the more fuel you use. If you have central heating and you are away in cold weather, leave the heating on continuously with the thermostat set to low to stop your pipes freezing.

How do I keep my pipes from freezing without power? ›

Keep your pipes from freezing by shutting off the valve that allows water to come into your home. Then, open any drain valves and all faucets and let them run until the pipes are empty (it's helpful to identify these valves in advance).

Does foam pipe insulation prevent freezing? ›

While insulated pipes are better than pipes with no protection, they're not the best solution to achieve full frost prevention during the winter months. In fact, pipes in unheated areas such as basements, garages and attics are still at risk of cracks and bursts even with proper pipe insulation.

How much difference does pipe insulation make? ›


Insulating your hot water pipes reduces heat loss and can raise water temperature 2°F–4°F hotter than uninsulated pipes can deliver, allowing you to lower your water temperature setting. You also won't have to wait as long for hot water when you turn on a faucet or showerhead, which helps conserve water.

Should copper pipes be insulated? ›

There are several reasons why it's essential to insulate your copper pipes. The most important reason is temperature regulation; when the temperature outside drops below freezing, the water in any exposed pipes could freeze and expand, which can cause the pipe to burst.

Should I wrap my outside faucets? ›

If you want to minimize the damage, the best way is to cover your outdoor kitchen faucets so you can protect them from frosty temperatures because when the season is cold, water can expand and pipes can rupture badly.

Is PVC pipe freeze proof? ›

Although PVC is a great choice to maintain heat, keeping the water inside the pipes quite hot, PVC doesn't do well in freezing temperatures. Plastic is brittle, so at low temperatures, PVC can crack.

Is it OK to use expanding foam around pipes? ›

Yes indeed it is suitable and also if pipes are copper.

Will spray foam work below freezing? ›

In theory, you may be able to apply cold cell spray foam at temperatures as low as 5 degrees Fahrenheit, but to ensure quality we recommend that you follow the 40 degrees Fahrenheit guideline.

Where should you not use expanding foam? ›

Avoid using the foam near any ceiling lights or heating appliances. If you spray the foam near a ceiling light, for example, there is a chance that it could catch fire due to the flammable nature of the spray. Additionally, it could also cause damage to the light itself if it cures around any wiring.

Is bubble wrap good insulation for pipes? ›

Pipe wrap foam is great for insulating exposed pipes during the winter. But if you don't have what you need on hand and you see a place you missed, try using bubble wrap. You easily can wrap it around most pipes, and it works pretty well.

What is too cold for spray foam? ›

The Risks of Applying Spray Foam in the Winter Months

It takes a well-seasoned expert to apply spray foam in temps below 32 degrees. The resin in spray foam is more sensitive in the cold, causing it to become thicker and possibly even freeze.

What is the lowest temperature for spray foam insulation? ›

Ideal Temperature for Spray Foam Insulation

When spraying, you want the room's temperature to be at least 40 degrees Fahrenheit. Depending on the manufacturer and contractor, you can technically apply spray foam insulation at temperatures as low as 5 degrees Fahrenheit.

Why is spray foam a problem? ›

Recent media and industry reports suggest some homeowners have found it difficult to remortgage or sell properties that have spray foam insultation. If installed incorrectly, spray foam insulation may lead to condensation which can affect a roof structure.

How long does it take pipes to freeze at 32 degrees? ›

With this in mind, expect most pipes to freeze within six to eight hours. Uninsulated exterior pipes can freeze in under six hours if the temperature is below 20 degrees. It takes at least 12 hours for unprotected pipes to freeze at 32 degrees.

What temperature should I keep my house in winter so pipes don t freeze? ›

1. Set your thermostat at 70 degrees. Seventy degrees Fahrenheit is the optimal temperature to prevent frozen pipes, even in below-zero temperatures. So remember to set your thermostat before the below-zero temperatures hit, and to keep the temperature consistent throughout the day and night.

How long can a house go without heat before pipes freeze? ›

The rule of the thumb is that it takes roughly 6-hours for water in your pipe to freeze after left in an unheated area. Meaning if you lose power at your home and the weather is reaching below freezing point, you have approximately 6-hours until the pipes will begin to freeze.

How do you insulate outdoor pipes from freezing? ›

Small lengths of exposed pipe can be protected by insulating with pipe-wrap insulation. This flexible insulation comes in several forms. Options include rubber tape-backed flexible foam, bubble wrap style, foam and foil insulation, rubber pipe insulation tape, or foil-backed natural cotton wrap.

What should I wrap my outside pipes with? ›

Use a “pipe sleeve” or similar insulating material on exposed water pipes. Newspapers can provide some degree of insulation and protection to exposed pipes – even one-fourth inch of newspaper can provide significant protection in areas that usually do not have frequent or prolonged temperatures below freezing.


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