Eerie sounds are best when they’re a part of a horror movie — not your house! If you’re constantly hearing a knocking noise in house walls, something needs to be done. 

But, before you call the ghostbusters, know that there’s usually a simple explanation for why your walls are making a knocking sound. Most often, it’s your home’s plumbing system.

Sometimes it’s due to fluctuating water pressure issues, loose plumbing pipes, or a faulty valve. Let’s learn about the possible causes of knocking noises in your pipes and what can be done about them. 

Read more: Essential home plumbing maintenance tips 

Loose water supply pipes

water supply pipes

The pipes supplying hot and cold water to your faucets may become loose from their straps over time. And that’s when the water pressure — passing through these loose pipes — causes them to bang against the wall. 

Such a problem occurs only while the water is running; you’ll notice that the banging noise stops the moment you shut off your water. It’s a sure-shot sign that the loose pipes are the culprit, and there’s no danger or serious issue.

Solution: If you can reach the troublesome pipe, try to fasten the strap to the wall  — all the while being careful to leave the pipe sufficient space so that it can expand and contract due to changing water temperatures. If the noisy pipes are installed within a wall, you may want to stuff padding or foam at the ends where the pipe enters and exits the wall.

High water pressure

In case the water pressure in your home is too high, the plumbing pipes may rattle despite being secured to the wall. Here too, you’ll notice that the sounds only occur while the water is running. This type of noise will be more of a quiet tapping sound rather than a full-on knocking. 

Solution: Ensure that your water pressure is between 40 and 80 psi. If the cold water pressure is more than that, you might want to install a pressure-reducing valve. And, if the problem occurs when you turn on the hot water, try turning the temperature down a bit. Or else, consider installing a hot water expansion tank that will absorb the excess pressure.

Water hammer

If you notice loud knocking sounds only when you shut the water off, it’s an indication that your plumbing system is probably suffering from a water hammer. It’s when the valve suddenly shuts — forcing water to bang into the valve. This problem usually occurs in older homes (built before 1960). Such houses probably have air chambers that can become filled with water.

Solution: For a quick fix, you should try turning off the water main and running all your faucets — draining the excess water from your pipes. This generally stops the water hammer. Fortunately, newer homes have water hammer arrestors which are like shock absorbers for your pipes. Just make sure the arrestors are working properly or you’ll have to hire a professional plumber to install new ones.

Copper pipes

Many older homes come with copper pipes and fittings which tend to expand when hot water passes through them. If the pipes travel through tight spaces, the expansion can make the pipes rub against the surrounding features.

Solution: While such a situation doesn’t usually cause any leaks, it’s a good idea to replace the copper pipes or to add padding around them in order to prevent the clanking noises.

Other common noises in house walls

common noises in a house

Clanking sounds

Any clanking noise in your walls or ceilings might be because of your HVAC system or to be more specific, your aluminum ductwork. When you turn your heat on for the first time at the beginning of the winter months, your ductwork may expand and contract due to the change in temperature. If the problem continues, it’s best to have an HVAC contractor check your system and ductwork.

Bubbling and popping sounds

More often than not, an old water heater is a culprit. Over time, with prolonged use, sediments build-up at the bottom of the water heater tank. They then bubble and pop as the water heats. Furthermore, gas water heaters and propane-heated tanks also sometimes make popping sounds as they light up. The solution is to have your hot water heater cleaned regularly to avoid sediment build-up. Or, if your heater is really old, replace it altogether.

Loud banging noises

If there’s a loud bang in your house, and you’ve thoroughly checked your home appliances, you should check to see if any of the nearby trees are banging against your house walls. Another probable reason is an improperly installed deck that’s shifting as the ground freezes and thaws.

Read more: Deck loans & financing options

Whistling noises

A low whistling sound in your home is likely due to the venting and airflow. A dirty air filter in your HVAC system restricts the airflow through the ducts. As a result, the air is pulled from the outer edges of the filter — creating a whistling sound. It’s advisable that you change the air filter regularly to avoid putting a strain on your heating or cooling system.

Read more: Different types of air filters and their pros and cons

Scratching sounds

Sometimes, the culprit of a mysterious noise in the house could be a rodent! The little beasts could be hiding in your ductwork and turning your home insulation into their cozy bed. Remedy the situation by setting traps and making sure all cracks and holes leading up to your home are sealed tightly.

Read more: Gas line sediment trap

Last words

Houses make strange noises on a regular basis — blame it on the house settling. But, a good homeowner should be able to tell whether a weird sound such as groaning, creaking, thumping, or popping could possibly be a sign of a serious or dangerous issue.

Normal knocking noise in house walls is rarely as bad as it sounds. Whatever the cause, you must analyze the problem, look for the solution, and cure your home of any annoying knocking.

If you continue to hear noises that are never-ending, it may be time to schedule a home inspection to find out what’s going on.

Read more: All about drain traps

If you need a friendly abstract, look to this infographic:

Knocking noise in house walls by raf howery

Top reasons there’s a knocking noise in house walls was last modified: December 28th, 2022 by Ramona Sinha
Your opinion matters, leave a comment
Inline Feedbacks
View all comments