Mudroom Dehumidifier: Handling Moisture From Outdoor Shoes

Why the mudroom gets damp

A mudroom is the busiest moisture transfer point in a house. Everyone who comes in from rain, snow, or wet ground brings water in from boots, shoes, pant cuffs, and bags. The CDC points out that mold in the air outside can attach itself to clothing, shoes, and pets and be carried indoors. So the dirt and water you wipe at the door are not all that arrives: spores come along as well.

Wet shoes left on a mat keep evaporating long after you take them off. Boots that hold snow melt into puddles. Coats and hats drip. If the mudroom also holds a laundry machine, a pet's water bowl, or a stack of reusable bags, the moisture load only grows. None of that is a problem by itself, but it is exactly the kind of damp surface mold needs.

Moisture control is the goal

The EPA's guidance on mold is blunt: the key to mold control is moisture control. Mold spores are everywhere indoors and out, and none of them will grow without water or moisture. So a mudroom dehumidifier does not fight mold directly; it removes the water that mold would otherwise use. The EPA also notes that you should dry water-damaged areas and items within 24 to 48 hours to prevent mold growth, which is the same reason to dry wet gear promptly rather than leaving it in a heap.

The CDC recommends keeping the humidity level in your home as low as you can, no higher than 50%, all day long, and says an air conditioner or dehumidifier will help keep the level low. A mudroom dehumidifier turns a room that is periodically wet into one that stays comfortably dry. See What Humidity Should You Set Your Dehumidifier To for more on choosing a setpoint.

Sizing a mudroom dehumidifier

ENERGY STAR explains that the size of a dehumidifier is measured in pints of water removed per 24 hours, and that the capacity you need depends on two factors: the size of the space and the conditions that exist in the space without dehumidification. It adds a practical note: it is better to oversize than undersize. For a mudroom, a unit from the under-50-pint class is usually enough if the room is small and only moderately damp. If the mudroom opens into a hallway or a family room, you are dehumidifying that whole area, not just the bench and shoe rack.

You can estimate the condition of the space the way ENERGY STAR does. A space that feels damp and has a musty odor at 50 to 75% relative humidity is slightly to moderately damp. One that consistently feels and smells damp, with damp spots appearing on walls and floors, is very damp. One where walls or floor sweat, or where laundry drying adds load, is wet. The table below gives the recommended capacity ranges for small and large rooms.

Mudrooms almost always fall in the small-room column, but the large-room column matters if the unit has to serve an open floor plan. For a longer walkthrough of sizing, see How Many Pints Do I Need? A Dehumidifier Sizing Guide.

One more note on ratings. Since 2020, portable dehumidifiers are tested in cooler conditions that more closely match a basement setting, so a new unit's capacity rating can look smaller than the model it replaces. ENERGY STAR's comparison shows an old 30-pint portable rated at roughly 20 pints under the new method, so judge a mudroom unit by its current rating, not by what an older machine was called.

Drain options: bucket or continuous hose

ENERGY STAR notes that most portable dehumidifiers use a removable plastic bucket with a warning light and an automatic shutoff when the bucket is full, so you will not worry about overflowing. That is fine for occasional use, but a mudroom can fill a bucket quickly on rainy days. If you have to empty it several times a day, the unit spends more time off than on, and the room stays damp.

A better choice for a mudroom is a model with a drain hose fitting. ENERGY STAR mentions that some dehumidifiers come with a fitting that lets you hook a hose directly to the bucket, which can then be directed into a floor drain or sump pump, so there is no need to empty it. In a mudroom, that hose can run to a nearby floor drain, a utility sink, or even outside if the climate allows. Look for a unit with a continuous drain option, and check the hose size and connector so it matches your setup. See How to Set Up Continuous Drainage on Your Dehumidifier and Dehumidifier Drain Hose Size and Connection Types for details.

Cold weather and low-temperature performance

Mudrooms are often at the edge of the house, near the entry door, and can run cooler than the rest of the home in winter. ENERGY STAR notes that if the space being dehumidified has temperatures that typically fall below 65 degrees Fahrenheit, you may want to consider a product specified for lower temperatures. Frost can form on the condensing coils below 65 degrees and cause the compressor to cycle on and off without removing moisture. Some dehumidifiers have an anti-frost sensor that turns the unit off automatically in that situation.

If your mudroom stays cool in winter, look for a model that states a low operating temperature range, and consider one with automatic defrost. See How Low Temperatures Affect Dehumidifiers and What to Check and What Is Auto Defrost on a Dehumidifier and Why It Is Important for what those features mean. A desiccant dehumidifier can also handle cooler temperatures better than a compressor unit, but it uses more energy; see Desiccant vs Compressor Dehumidifiers for a comparison.

What to pick for your mudroom

Start with the room size. If the mudroom is under 1,500 square feet, a compact portable from the under-50-pint class will handle the load. For a larger open area that includes a hallway or a laundry corner, step up to a 50 to 99 pint unit. ENERGY STAR's sizing table uses 2,000 square feet as the breakpoint between small and large rooms, but that assumes a wet condition; a typical mudroom is closer to moderately damp unless you are drying clothes there.

The most useful features for a mudroom are a continuous drain option, a low-temperature operating range, and a humidity readout so you can confirm the unit is holding your setpoint. A built-in pump is not necessary unless you need to lift the hose to a drain; see Built-In Pump or Gravity Drain to decide. An energy-efficient model, ideally ENERGY STAR certified, will save on electricity if the unit runs often; see Dehumidifier Energy Efficiency.

• Size for the whole space the unit will serve, not just the shoe cabinet.
• Prefer a continuous drain hose over a bucket, or choose a model with both options.
• Check the minimum operating temperature if the mudroom gets below 65 degrees Fahrenheit.
• Look for a humidistat with clear readout and a setpoint you can adjust.
• Keep the unit away from direct walls and allow airflow around it; see Where to Place a Dehumidifier for Best Results.

What to pick for your use

Questions

Will a dehumidifier damage my shoes or boots?

No, a dehumidifier removes moisture from the air, which helps wet shoes and boots dry faster. The air it blows is not hot enough to damage materials. Keep shoes on a rack so air circulates; direct contact with the unit's outlet is not needed.

How low should I set the humidity in a mudroom?

The CDC recommends keeping indoor humidity below 50% to prevent mold. For a mudroom that gets damp from wet gear, setting the dehumidifier to 40-50% is a safe range. Lower than 40% may be uncomfortable in winter and wastes energy.

Can a small dehumidifier handle a mudroom with a washer and dryer?

Laundry adds a lot of moisture. If the mudroom contains a washer and dryer, you need a unit sized for the combined load. ENERGY STAR's sizing table lists 'wet' conditions at 90-100% relative humidity, which calls for a larger capacity, often in the 50-70 pint class for a small room.

Do I need a bucket or a drain hose?

A bucket is fine if you check it daily, but a drain hose is more convenient for a mudroom that sees frequent wet traffic. A continuous drain lets the unit run unattended, and you never have to worry about the bucket filling up while you are away.

Will a mudroom dehumidifier help with musty smell?

Yes, a musty smell usually means mold or mildew is growing somewhere damp. By keeping humidity below 50%, you prevent that growth, and the smell fades once the source is cleaned and the room stays dry. The EPA notes that if you clean up mold but do not fix the water problem, the mold will return, so a dehumidifier is part of the fix.