How to keep pipes in exterior walls from freezing?

Author: Chad Macejkovic  |  Last update: Wednesday, December 10, 2025

If critical water pipes are freezing inside an exterior wall, cut an opening in the wall to expose the pipes to the home's warm air. You can run fiberglass insulation behind the pipes, between the pipes and the home's exterior wall.

How to prevent exterior wall pipes from freezing?

One effective measure is to insulate your pipes, especially those in unheated or vulnerable areas such as attics, basements, or crawl spaces. Pipe insulation sleeves or wrapping with heat tape can provide a barrier against the cold. Maintaining a consistent indoor temperature is essential.

How do you insulate water pipes in exterior walls?

Spiral insulation wrap can be made of fiberglass, foil, or polyethylene foam. The homeowner can simply unroll the material and wrap it around the hot and cold water pipes. Pipes can also be wrapped with fiberglass insulation.

At what temperature will outside water pipes freeze?

Your pipes are at risk of freezing any time temperatures drop below 32°F. However, it's much more common for pipes to freeze when temperatures dip below 20°F. The longer the weather remains below freezing, the more likely it is your pipes can freeze if not properly protected and winterized.

Will bubble wrap keep outside pipes from freezing?

Protect faucets, outdoor pipes, and pipes in unheated areas with pipe insulation. If insulation is not an option, consider wrapping them with rags, newspapers, trash bags, plastic foam, or bubble wrap. Cover vents around your home's foundation so drafts can't sneak in.

How to Prevent Frozen Pipes | This Old House

Will shutting off water keep pipes from freezing?

Prevent Frozen Pipes

Moving water keeps pipes from freezing. Find shut off valves for emergencies. Insulate pipes in unheated areas. Open cupboards and vanities to warm pipes.

What is the best pipe insulation to prevent 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.

Should you drip all your faucets?

Set faucets to a small, steady drip rather than a stream to conserve water while preventing freezing. Drip the faucet farthest from your home's main water valve. “You don't have to drip them all—one or two is fine,” Sperlich told USA TODAY.

What is the best insulation for exterior walls?

Foam Board or Rigid Foam

Foam boards -- rigid panels of insulation -- can be used to insulate almost any part of your home, from the roof down to the foundation. They are very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches.

How to seal pipes through exterior walls?

For faucet pipes through exterior walls, install a rubber gasket or flashing around the pipe on the exterior wall, if possible, in addition to caulking. Integrate the gasket or flashing with the house wrap above the pipe. Check plumbing vent pipes for cracks and seal with caulk or acoustical sealant.

Will spray foam keep pipes from freezing?

Many times, fiberglass is not adequate. Fiberglass insulation cannot and will not provide an air barrier. Conversely, spray foam can. Spray Foam is the best option to keep pipes insulated from the freezing outdoor air.

What is the best way to insulate pipes on an outside wall?

Use caulk or foam to seal any holes where the pipes penetrate walls, floors, ceilings, or framing. If pipes run through exterior wall cavities, insulate the wall cavity just as you would the other cavities if using blown cellulose, fiberglass, or spray foam, which will easily fill in the space behind the pipes.

Which house pipes most likely to freeze?

No matter the strength of a container, expanding water can cause pipes to break. 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.

Can you put heat tape inside a wall?

Due to its potential to overheat and cause a fire, do not use heat tape on pipes behind walls or ceilings. It should only be used for exposed pipes, such as those found in your crawl space or outside your home.

Do foam pipe covers work?

The foam pipe insulation works by creating a barrier between the pipe and the surrounding environment. This barrier slows down the rate of thermal transfer, reducing the amount of heat loss in winter and preventing overheating in summer. The closed air pockets within the insulating foam restrict the flow of heat.

How to stop external pipes from freezing?

Insulating your pipes and water tanks is one of the best ways to prevent them from freezing. You can buy inexpensive pipe lagging and tank jackets from most DIY stores and fit them yourself for free. Just make sure you check the pipe and tank measurements first.

Can pipes freeze in one night?

Yes, pipes can freeze overnight if temperatures plummet drastically. Uninsulated pipes in unheated areas like attics or exterior walls are most vulnerable.

Should I just turn off water to the house if it's going to freeze?

DURING freezing weather:

If you plan to be away from home for several days, shutting off the water can reduce the chances of broken pipes. Set your home heat to at least 55 degrees. Shut off water to the house and open all faucets to drain pipes; flush the toilet once to drain the tank, but not the bowl.

What can I use instead of pipe insulation?

Insulation Methods and Materials
  • Duct tape.
  • Expanding spray foam.
  • Foam caulk rope.
  • Insulation of choice (pipe sleeve, pipe-wrap, outdoor faucet cover)

Will pool noodles keep pipes from freezing in winter?

Insulation is a great way to ensure your pipes don't freeze. There are special pipe insulation products you can buy, or if you're on a tight budget you can use a pool noodle and fashion it around your pipes so they stay protected from the outdoor temperatures.

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