What It Means If You Hear A Hissing Sound Coming From Your Walls

Houses can emit strange noises from time to time. Some of them are easy to explain. For example, your creaking house probably isn't caused by ghosts — it's likely just wood in the home expanding and contracting with changing humidity levels. If you're hearing hissing noises coming from inside the walls, though, the exact cause may be tougher to pinpoint. 

The sound could relate to some sort of leak if you have natural gas or water pipes behind the walls. This is the most dangerous situation and requires immediate inspection as water or gas could be under pressure inside the pipes. The noise could also be from some sort of leak inside your heating or cooling ductwork. Regardless, if you suddenly hear hissing inside your walls, call in a professional for an inspection, and turn off the gas or water until you can be certain about the source.

Some hissing noises could have a more natural cause, such as snakes secretly living inside your home. One or more may have found rodents living inside the walls as they entered your home in search of food. Snakes can fit through tiny spaces, so if you have rodents on your property, it's possible you could have reptiles, too. When you call an exterminator to help with the problem, be sure to ask if the company handles snakes, as not all of them do. Removal experts will often determine where these pests are entering your home.

A natural gas leak is especially dangerous, as it can cause physical ailments like lightheadedness, drowsiness, breathing problems, and a ringing in your ears. If concentrations of natural gas are high enough, you could die from asphyxia. Should someone introduce an open flame to the natural gas-laden air, it could cause an explosion. Even though some gas leaks cause hissing, small leaks may not make any noise. This is why utility companies add a chemical to the fumes — mercaptan — that mimics the smell of sulfur, making it easier to detect a potential leak.

If a leaking water pipe is causing the hissing noise inside the walls, there's no danger of asphyxia or an explosion. However, even a small, constant drip of water from a leaking water pipe can cause significant damage to the home in very little time. Water damage can stain and warp your walls, too. Mold is another danger that comes with water leaks. If left unchecked, they can damage the structural integrity of your home.

If the hissing noises don't relate to natural gas or water pipes — or snakes — the most likely cause is a leak or an anomaly with your heating and cooling system. Leaky ductwork inside your home may emit sounds as warm air from the furnace or cool air from the air conditioner squeezes through any crack or loose connection. The good news is that losing air in this manner isn't a danger for your home. 

However, you will be losing money through wasted energy. Your furnace or AC unit must work harder to overcome the leaks behind the walls to keep the interior of the home at the desired temperature. According to the U.S. government's Energy Star program, fixing leaky ductwork could improve your heating and cooling system's efficiency by as much as 20%. Technicians may be able to fix the issue with leaks by spraying a polymer sealant liquid into the ducts.

One final potential cause of hissing noises inside your walls is an older radiator. Most sounds related to this fixture are not dangerous. However, if you have an older home that specifically uses steam radiators, a hissing noise could indicate pipes that are under too much pressure and need repair.