What's that sound? Things that go bump or thump in the night (or day) and possible causes

ON THE WEBTo listen to some of these sounds, go to:• Gurgling drain• Humming refrigerator• Thumping washer• Creaking floor• Animals in the attic

When you lay in bed at night listening to pops and squeaks, is it really the "house settling" or a forewarning of a deeper problem?

There's usually a practical cause for those bumps, bangs and whooshes you might hear at night (or any time of day, actually, it's just that everything sounds louder in the quiet of the night). We asked local professionals what might be behind 10 unusual home noises as well as whether a home handyman can fix these problems. Some are DIY projects, some will require calling a professional.

1) Gurgling toilet.

"This usually means the drain line is starting to stop up and it's reducing air flow in the system to the vent, so water going into drain lines is displacing air, which is coming back up to the trap. If your home is on a septic tank, it may need to be pumped. Either way, call a professional."

- Eddie Lewis, East Brainerd Plumbing

2) When you flush the toilet, you hear banging in the walls.

"That's usually an indicator that the pressure regulator has failed and pressure is too high (in the pipes.) Occasionally, it might be a pipe strap has come loose and the pipe is flopping around in the wall. If this is the case, it will require cutting into the Sheetrock and tightening up the strapping." Call a pro.

- Eddie Lewis, East Brainerd Plumbing

3) Humming sound from the refrigerator.

"That's a sign of a bad compressor. It could be something stuck in the fan, but more likely it's a bad compressor." Call a repairman.

- Greg Nesbitt, Woodlee Appliance

4) Squeaking from the dryer.

"Either the rollers or the bearings have gone bad." Call a repairman.

- Greg Nesbitt, Woodlee Appliance

5) Hissing water faucets.

"If you hear hissing and you can't see water running, it means water is running somewhere else and the sound is transmitting to that point. It could be the toilet, faucet or somewhere outside.

"Go to the water meter, and there is an indicator to show if there's a leak. If all the water is off in the house, but the indicator is spinning, you have a leak. With this freeze we've had, everyone needs to look under their house, walk all around the outside of the house and check for leaks."

"Once the leak is found, homeowners can decide whether it's a do-it-yourself project."

- Eddie Lewis, East Brainerd Plumbing

6) Thumping from the washing machine.

Best case scenario: Spin cycle is thrown off balance by clothes lumped together on one side. "If the clothes are one side, the machine is out of balance and it will rock back and forth (making the thumping sound)."

If adjusting the clothes in the tub doesn't fix the problem, it could be a bad transmission. "They are two different sounds, and the homeowner will be able to tell the difference." Call a pro for transmission repair.

- Greg Nesbitt, Woodlee Appliance

7) Creaking, squeaking stairs.

Years of use loosen wooden boards, and homeowners can tighten them in a DIY project.

"Instead of using a finishing nail, use a long wood screw to secure the tread OVERSET FOLLOWS:along with a strong adhesive like Liquid Nail or Gorilla Glue."

- Rodney Revis, Interior Trim and Supply

8) Whooshing or rattling windows.

"Rattling is caused by air infiltration. A lot of times, wood or aluminum windows have a tendency for this because those materials tend to expand and contract, which causes air leaks between sashes and frames. The best solution is to replace these older windows because a lot of new window materials don't expand and contract. They are better insulated and all new windows have weather stripping, so they are much more energy efficient."

- Brian Brock, Hullco

9) "Whoosh" from the HVAC unit.

"That's the defrost cycle. It cuts off the outside fan. It's normal."

During cold weather, ice can form on the coils of the condensing unit, which makes the unit go into defrost cycle.

"The unit has to melt the ice off with a defrost cycle. When the unit goes into defrost, it goes into air conditioning mode. The whoosh is the valve reversing the flow of refrigerant back to heat pump mode."

- Tommy Rayburn, Chattanooga Heat and Air Co.

10) Rustling, scratching or chewing sounds in ceiling or walls.

"That's either squirrels, raccoons, rats or even possums. Raccoons and possums are nocturnal, so you'll hear them going out at night or coming back in the morning. Squirrels you'll hear going out in the morning and coming back toward dusk. Rats you hear anytime. Call a professional for wildlife removal."

- Joseph Strickland, Bio-Lab

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