Why is my house always dusty?

If the furniture is dusty again two or three days after you clean, the dust is not just settling. Something keeps bringing new dust in. Part of it may be coming from the attic, through small gaps in the ceiling you never see.

Here is how that happens, how to tell if it is happening in your house, and what actually stops it.

Why does dust come back so fast?

Every house makes some dust: skin flakes, fibers from clothes and bedding, pet hair, and dirt that comes in on shoes. That kind builds up slowly, over a week or more.

When it comes back in a few days, there is usually a steady source feeding it. The most common one is air that comes into the house without going through a filter. That air brings whatever is in the space it came from. If it came from the attic, it brings attic dust.

How attic dust gets into your rooms

Your ceiling looks solid, but it has holes in it. Each one is a path from the attic into the house:

• Lights and ceiling fans. Recessed lights and fan boxes are cut right through the ceiling. Most are not sealed around the edge.
• The attic hatch. The door into the attic is usually a loose panel with no seal.
• Wires and pipes. Every wire and pipe that runs up into the attic leaves a hole behind.
• Air ducts in the attic. If the ducts run through the attic and leak, the system can pull attic air in and blow it out of the vents in every room.

Holes alone do not move dust. Air has to move through them, and it does, every day. When the bathroom fan, the kitchen hood or the dryer runs, it pushes air out of the house. The same amount of air has to come back in from somewhere, and part of it comes down through the ceiling.

Hot days make it worse. When the house is cooler than the air outside, cool air slowly leaks out low down, and air gets pulled in up high. Up high is the ceiling, and above the ceiling is the attic.

Your house is always breathing. The question is where the air comes from.

Is attic dust harmful?

An old attic is not just dusty. Over the years it collects broken-down insulation, dirt that blew in through the vents, and, if rats or mice ever got in, their droppings and nests.

Rodent droppings are the part to take seriously. The CDC tells people not to sweep or vacuum them, because the dust they make can carry disease. That dust does not stay in the attic if air from the attic is coming into your rooms.

We are not doctors. If someone at home has allergies or asthma that get worse indoors, ask your doctor, and mention the attic.

Will a better air filter fix it?

A good filter helps, and you should change it on schedule. A higher-rated filter catches finer dust, but check that your system is made for it first.

The catch: a filter only cleans air that goes through your heating and cooling system. Air that comes in around a ceiling light goes straight into the room and never touches the filter. An air purifier has the same limit. It cleans the air in one room, but it does not stop more dust from coming in.

So if the filter is new and the house is still dusty, the filter is not the problem.

Check these first

Not all dust comes from the attic. These cost little or nothing, so rule them out before you call anyone:

• The air filter. A full or cheap filter lets dust pass straight through.
• Carpet, rugs, bedding and pets. They hold dust and release it every time someone walks across the room or sits down.
• Windows and doors. Open windows on a windy day, or worn seals around the doors, let street dust in.
• How you dust. A dry cloth or feather duster moves dust into the air, and it lands again an hour later. A damp cloth picks it up.

If you have done all of this and the dust keeps coming back, look up.

Signs the attic is the problem

• Dust comes back a few days after you clean.
• Gray or dark marks on the ceiling around vents, lights or the attic hatch. That is dust caught as air passes through the gap.
• A dusty or musty smell when the AC turns on.
• The insulation up there is old, flat, or dirty.
• You have had rats or mice in the attic, or you hear scratching at night.

One or two of these do not prove it. Several together are worth a look.

How Jacob stops it

Dusting more does not fix it, because the source is still open. The fix is to clean the attic and then close it off from the house. Jacob does it in this order:

1. Jacob comes out and looks

   He checks the attic himself and tells you what he finds. The estimate is free.

2. Strip and clean

   Old insulation, droppings and debris are taken out.

3. Sanitize

   The attic is sanitized before anything new goes in.

4. Seal the attic from the house

   The gaps between the attic and your rooms are closed, so dust, rodents and debris stay out.

5. New insulation

   Pro-grade material, not the kind sold at hardware stores. Guaranteed for 60 years.

Jacob has done this work in Los Angeles since 2001. You deal with him directly, from the first call to the last day of the job. Rodent work comes with a lifetime guarantee.