Explanations for what goes bump in the night 

Have you ever been sitting at home relaxing on a quiet evening and all of a sudden you hear a sound? It might be a constant tapping, a whistle or even a loud pop. Before you panic, here are some explanations for unusual sounds that houses make.

 

Tapping: Perhaps the most common sound encountered in homes is a steady tapping. In most cases this sound can be attributed to the expansion and contraction of building materials.

Most houses in North America are built largely of wood or wood-based materials. Metal and plastics are also used for plumbing piping and for heating and cooling duct-work.

All of these materials will expand and contract with changes in temperature and humidity. Often the steady tapping noise occurs when someone in the house is using the hot water. This can be when using the bathroom or the dishwasher or clothes washer.

The steady tapping sound results when the wood and/or metal or plastic hot water pipes expand or contract and rub against wood framing members. If you hear this sound, try to determine if it is related to use of hot water and remember it might also occur as the pipes cool off.

Popping: This is also usually the result of building materials expanding and contracting. Often it happens during very cold or very hot days. The popping noise is usually caused by the wood framing expanding or contracting.

Sometimes, the expansion or contraction is held by nails until it is extreme enough to finally move. This sudden release of pressure will result in a popping or even a banging sound. This sound can often be quite loud and even result in a minor vibration.

Although it can be alarming, this kind of movement usually poses no threat to the structure of the house.

Popping sounds can also occur because of expansion and contraction of the heating and cooling ductwork. The pressure created when the blower fan in your furnace comes on can push the metal ductwork out. When the fan turns off the ductwork will contract back into position causing a pop or bang.

Banging or rattling: These sounds often occur when plumbing fixtures are turned on or off. It typically will occur most often when fixtures are turned off. This phenomenon is called “water hammer.”

When the water flow is stopped by turning off a fixture it will send a vibration through the piping that can make the pipes rattle. The best remedy for this condition is to install a water hammer arrestor.

Unless you are extremely handy I would recommend having a water hammer arrestor installed by a licensed plumber. When trying to find a pattern to the sound, remember that your dishwasher and clothes washer are plumbing fixtures, too.

Humming or singing: These sounds are most often related to plumbing. They can be caused by a small amount of water flowing through a valve.

Sometimes replacement of the valve, or the washer in the valve, is the only solution. Before trying anything else, check the water pressure in your house, using a gauge you can buy at a hardware store.

Put the gauge on the drain valve on your water heater and open the valve. The gauge will tell you your house pressure.

One word of caution, if your water heater is located in an area where leaking would cause damage, I recommend installing the gauge on the cold water supply for your clothes washing machine.

If this location is not accessible you can put the gauge on a hose bib. Since hose bibs on the front of the house are often left at street pressure, use of the rear hose bib is preferable. If your house water pressure is greater than 80 pounds per square inch (psi), this elevated pressure can cause the humming sound.

I recommend calling a licensed plumber to install or replace your pressure reducing valve.