Water leak from pipes freezing. Water Damage Is Serious Business:

Frozen and Burst Pipes:
It Can Happen To You

 
In This Article:

Why plumbing pipes sometimes freeze and burst in cold weather, and how to avoid this problem.

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By , Editor

February 2008

Frigid Real Estate:

In any area with cold winters there is a risk of plumbing pipes freezing during cold weather.

I started writing this article to share some tips on reducing the chances of pipes freezing and reducing the flood damage if a pipe should actually burst. It seems that everybody knows somebody who has experienced a burst pipe or a flooded basement.

While writing this article my drywall-contractor friend Tod dropped by and told me a story about a house he had just looked at. It was a foreclosure sale and the bank was trying to sell it through a realtor. The rural house was vacant and being offered at a good price. When Tod walked in, the house was stone-cold, but he could hear water dripping. He opened the door to the basement stairs and was greeted by three feet of water in the partially-finished basement. Water was spraying from a burst pipe and he could hear the well pump running.

According to the realtor, the home had been "winterized" by the previous owners when they moved out. It makes me wonder what some people think "winterizing a house" actually means. They did turn down the thermostat, but the propane tank ran out. They apparently didn't know to turn off the power to the well pump.

This scenario makes me wonder how many vacant, foreclosed houses in the northern states are facing a similar fate. These banks and mortgage companies often don't have any local staff, so there's nobody to monitor their collateral as it languishes on the market. The realtor should have known to at least turn off the circuit breaker to the well pump, but she didn't. A smart realtor would have also paid somebody to drain the plumbing supply pipes and pour RV antifreeze in the drain traps. A couple hours of work is cheap insurance... instead, all the parties involved just ignored the situation. Or maybe they just didn't know better. How can someone be in the real estate business and not know this? It will cost many thousands of dollars to repair the flood damage to this house, and it will come out of the lender's pocket.

 

Why Is Freezing Water Such A Problem?

If the temperature inside a house gets below 32 degrees Fahrenheit (0° Celsius) it's likely that the water supply pipes and the drain traps will freeze. When water freezes it expands 9 percent, and if there is no room for expansion it's possible that the pipe will develop a crack. When the ice thaws the pipe will leak, and in the supply system this leak could occur anywhere. Fixing a burst pipe can be expensive, but the damage from uncontrolled water leakage can easily reach into the thousands of dollars.

A properly-insulated house built to current building codes will probably never experience this problem under normal conditions. What do I mean by normal conditions? The heating system runs properly, the electricity supply stays on, and the furnace fuel supply never runs out.

 

When A Good House Goes Bad:

Even a well-insulated house with plumbing built to current codes can experience a disastrous water leak from frozen and burst pipes. But this problem usually only happens when the heating systems fails during cold weather and nobody is home to notice. The classic example is a house left empty while the owners take a winter vacation. There are several things that can go wrong:

  • The furnace can malfunction and fail to start. Some old furnaces use a standing pilot (a small flame that stays lit) which can be blown out by strong winds sucking air up the chimney. But there are lots of reasons why any furnace can malfunction.

  • The power can go out for a long period.

  • The fuel supply gets shut off. If the fuel is natural gas, there is a very small chance of the gas supply being interrupted, as long as the bill gets paid. However, if the furnace had a standing pilot and the gas was shut off for just a few minutes, the pilot will go out and stay out.

  • The fuel supply runs out. This is possible if the house is heated with propane or fuel oil and the homeowners go away, not realizing that the fuel tank is approaching empty. What if the owners go away for a short trip but are unable to return before the fuel runs out? If their fuel supplier regularly fills the tank (i.e. without needing to be called) this problem is avoided. But some people, for whatever reasons, aren't on the "automatic fill-up" plan. Those people need to be aware of the risk of running out of fuel if they go away during the winter.

The solution to this problem is simple: Have someone visit your house every day or two and make sure everything is working. This person needs to be able to reach you if something goes wrong, or be able to handle the problem. If you have an existing relationship with a heating system service company, make sure their phone number is easy to find (usually these companies will put their sticker on the furnace).

If it isn't possible to have someone check on the house, then it's wise to at least turn off the water supply. If a pipe bursts, only a few gallons of water will leak out, not thousands of gallons. The pipe will still need to be repaired, but that expense is much less than the damage caused by a gushing water leak.

 

When A Not-So-Good House Goes Bad:

There are two main weaknesses in a house that can allow pipes to freeze in cold weather: Inadequate insulation to keep all areas warm, and water supply pipes and fixtures that are not kept inside the insulated building "envelope".

Insulation: I have worked on many houses that have little or no insulation in the walls. Most of these homes were older. It seems that houses built after about 1975 were made with more attention to energy conservation. In the late 70's and early 80's many states developed building codes that required a certain amount of insulation... at least my state (Michigan) did this. Inadequate insulation is not an easy problem to fix, but it's important to keep this in mind when any remodeling is done, especially changes that involve removing drywall or exterior siding. I'm a big advocate of adding insulation to the outside walls whenever the siding is changed. On many remodeling projects I have also added a layer of foam insulation on the inside of the studs before installing drywall.

Plumbing: Any point where the plumbing supply pipes are close to the outside walls is a potential spot for freeze damage. Since most houses have the kitchen sink in front of a window, a common problem is pipes freezing beneath the kitchen sink. If the wall behind the sink doesn't have enough insulation, or if the insulation was installed sloppily leaving gaps (been there... seen that...) then there is a risk of supply pipes freezing beneath the sink. The kitchen cabinets can insulate the contents from the heat of the house. If there are any air leaks in the wall or sill area then freezing pipes may occur when there is a cold wind from a certain direction. A common recommendation is to leave open the cabinet doors beneath the sink, especially at night or when away from home for a long period.

 

An Example Of Freeze Damage:

Outdoor faucet (or sillcock).

An example from my own house illustrates how pipes can accidentally be put in harm's way.

The front of my house has a short section where the floor joists extend beyond the foundation. There was an outdoor faucet in this section.

 

The first time I turned on this outdoor faucet, water poured out from beneath the overhanging area. I removed the sheathing and fiberglass insulation to see the exact leak point (red arrow).

The faucet was a proper "sillcock" where the actual valve is about 12 inches behind the wall. Normally this type of faucet won't freeze because the water is stopped deep in the house where the temperature is warm.

The previous owner had installed insulation in the sill area, between the floor joists at the outside wall. BUT... he insulated above and below this pipe. Insulating above the pipe was a mistake because it kept the pipe away from the warmth of the house.

Leak caused by sillcock freezing when hose was left attached.

This was a classic example of a homeowner that didn't understand exactly where insulation should be placed. RULE: The pipes need to be kept on the warm side of the insulation. Pipes should never be placed in the middle of the insulation.

If you closely examine the above picture, you can see that the leak point was on the downstream side of the valve seat. This fixture only leaked when I opened the faucet... it never leaked when the faucet was off. When an outdoor faucet develops this type of leak it usually means that somebody had left a garden hose (or perhaps some kind of hose shut-off valve) attached to the faucet in freezing weather. These freeze-proof faucets can burst if the little bit of water downstream of the valve seat isn't allowed to drain.

So it's likely that this freeze damage was not caused by the insulation mistakes. But the insulation installed on the warm side of the pipe is still wrong.

Sillcock instructions say to disconnect hose in freezing weather.

This excerpt from the instruction sheet for a Mansfield frost-proof sillcock illustrates my point.

Manufacturers of these products always warn users to never leave a hose attached in freezing weather.

Remember: This type of leak can happen to ANY house if the sillcock is not allowed to drain because a garden hose was left attached.

 

 

Solutions:

The best solution is to build the house properly. If an older house has insulation problems, this can be fixed during remodeling. If the work involves removing drywall, then the wall cavities can be insulated properly. As I mentioned earlier, foam insulation can be added to the inside face of the studs, or to the outside walls before siding is replaced, or both. More insulation can be added to the attic, if there is access. These are worthwhile improvements because they also reduce the home's heat loss and therefore reduce the amount of energy needed to heat (and cool) the home.

But major changes are not in everyone's budget. A common solution is to apply electric heat tape around the vulnerable pipes. Some of these products are thermostatically controlled so they only operate when the temperature is cold enough to pose a freeze hazard.

 

The Simplest Solution:

If a house is known to have a problem with freezing pipes, the simplest solution is to leave the water running when the temperature is cold enough for pipes to freeze. Of course, you must first be aware of this problem, aware of the weather, and actually be home to run the water.

The usual advice is to let the faucet run with a stream of water about the same diameter as a pencil. That's a pretty serious rate of flow. If a house has hot and cold water lines that are vulnerable to freezing, then the stream needs to be warm water. This is a waste of energy, but sometimes that's the only solution available.

This solution works because the water supply is often quite warm. Here in Northern Michigan well water stays about 53 degrees all year around. Even municipal water supplies will stay quite warm (if the pipes are buried deep enough) because the ground doesn't often freeze more than a few feet deep.

But... there are some towns around here with municipal water service that experience wintertime freezing of underground water pipes. The problem is greatest at night because the temperature is coldest and most people are not using any water. The branch lines between the houses and the water main run a serious risk of freezing, so the town's water department will issue a notice telling everyone to leave one cold water faucet running with a pencil-sized stream of water. One town in my area does this almost every year in late winter.

 

Beware:

Some people have the notion that wrapping water pipes with insulation will prevent them from freezing. This is not necessarily true. I have seen pipes that were insulated and still managed to freeze. By wrapping pipes with insulation, there is a risk that the pipes will be insulated from the warmth of the house.

The main purpose of pipe insulation is to retain the heat in hot water lines. Insulation also has the benefit of reducing summertime condensation (sweating) on cold water lines.

Use pipe insulation with caution. Insulated pipes that run through a poorly insulated wall or floor cavity still run the risk of freezing. If the water is left running, then the pipe insulation will help retain the warmth of the water, so a smaller trickle of water can be used to prevent freezing.

 

What If Pipes Freeze But Don't Burst?

When the water inside a supply pipe freezes, it doesn't always damage the pipe. Galvanized steel and some types of plastic pipe are more rupture-resistant than copper.

If it's a cold winter morning and water doesn't come out of a faucet, chances are a pipe is frozen somewhere. Finding the exact frozen area isn't always easy. You might notice frost on the outside of the pipe... that's a sure sign of freezing.

Most people just use a hair dryer to warm up the pipes and wait for water to flow. Of course, you need to leave that dead faucet open so you can hear the water when it begins to flow.

If the pipes are concealed behind walls, floors, or ceilings, then it's a much bigger problem. What can you do?

  • Wait for the weather to warm up.

  • Turn up the heat.

  • Run an electric heater in the space where the suspected freeze point is located.

  • Cut a hole in the wall or ceiling and look around for frosted pipes.

  • Start a remodeling project sooner rather than later.

None of these options are very good. This problem seems to occur mostly in old houses that have not had their insulation updated. Fortunately, most of these older homes have galvanized steel water supply pipes, which is more capable of resisting the extreme pressures generated when pipes freeze.

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Written February 19, 2008