Why Does My Mattress Smell Musty?

You strip the bed to wash the sheets and catch a whiff of the mattress. Not sweaty. Musty. Like a cabin that's been closed all winter. Then you notice it a little every night when you lie down, and it's hard to stop noticing.

A mattress takes in moisture every single night from breath and sweat. Usually that moisture dries out during the day. When it can't, the smell starts.

Lift the corner of the mattress and look at the bottom and whatever it sits on.

- **On the floor?** A mattress directly on the floor, especially carpet or in a basement, can't dry from the bottom. This is one of the most common causes of a musty mattress. - **On a solid platform or a board?** Solid wood bases trap moisture the same way. - **On slats?** Usually better, unless the room is damp.

Look at the underside of the mattress for spots, stains, or a damp feel. Look at the platform or floor under it too.

If you see spots on the mattress fabric, especially on the bottom, it's often time for a new mattress. It's hard to get deep into a mattress to clean it.

If the mattress just smells but looks fine:

1. Strip the bed and wash all the bedding, including the mattress protector, in the warmest water the labels allow. Dry it all the way. 2. Vacuum both sides of the mattress with the upholstery tool. 3. Sprinkle baking soda over the top, leave it for several hours, then vacuum it up. 4. Prop the mattress up on its side and let air get to both sides. Open a window on a dry day and run a fan in the room. 5. If you can, flip or rotate it so a different side faces up. Check your mattress instructions, because many newer ones are one-sided.

Don't spray the mattress with water, and don't use a lot of cleaner. Moisture going in is the problem.

- **Get it off the floor.** Even a simple slatted frame lets air move under it. - **Use a breathable mattress protector** and wash it every couple of weeks. - **Pull the covers back in the morning** for an hour so the mattress can dry before you make the bed. It feels strange, but it helps. - **Keep the bed off the outside wall** by a few inches if that wall feels cold. - **Watch the room humidity.** If the windows in the bedroom drip in the morning or the closet smells, the room is damp. A humidity gauge helps you know for sure. - **Don't run a humidifier on high** right next to the bed.

Kids' mattresses go through accidents and spilled cups, and they're often on low frames or the floor. A waterproof cover helps, but it also keeps moisture in, so pull the bed apart and air it out often. If a spill soaks through, dry the mattress right away with fans and towels.

If you've aired the mattress out, it smelled fine for a few days, and then it went musty again, look around the room. Behind the headboard. Under the bed. The closet. The window sill. The bed is often just the biggest soft thing in a damp room.

This is a house check, not a diagnosis. Symptoms go to a doctor, and damp walls or a big patch go to a licensed pro.

When Your House Doesn't Feel Right is a picture book that shows how to wash and dry bedding, where to put a humidity gauge, and the other bedroom checks one photo at a time. It's $2.99 at https://clearnestair.com/book.