Shut the laundry room door to cut noise, and the dryer sounds happier. But here’s a curveball: most dryers pull 150–200 cubic feet of air per minute from the room, then push it outdoors. That air has to come from somewhere. Close the door in a tight space and the dryer can struggle for make-up air, run hotter, and take longer to dry. One average load sheds about 1–2 liters of water. If that moisture doesn’t leave efficiently, it can end up as condensation on walls and in ductwork. It matters for safety, efficiency, and your utility bill. You’ll learn how door position affects airflow, what’s different for gas vs. electric and vented vs. ventless models, how to size make‑up air openings, and the simple checks pros use to spot trouble. No scare tactics—just practical steps so you can dry faster, avoid moisture problems, and lower the risk of lint-related issues.
Quick Answer
If the dryer is vented to the outside and the laundry room has enough make‑up air (louvered door, transfer grille, or at least a 1-inch undercut), you can keep the door closed. In a small or tight room—or with a gas dryer—keep the door open during cycles or add grilles totaling roughly 60–120 square inches of free area to feed the dryer. Ventless/condensing units in small rooms benefit from an open or partially open door to manage heat buildup.
Why This Matters
A dryer moves a lot of air. At 150–200 CFM, it can depressurize a small, sealed laundry closet in minutes if there’s no easy path for replacement air. That pressure drop forces the dryer to work harder, extends cycle time, and wastes energy. It also increases exhaust temperatures, which isn’t what you want in a lint-prone system.
Moisture is another hidden piece. A typical load can release 1–2 liters of water. In a well-vented setup, that moisture gets expelled. In a starved or compromised system, it can condense on cool surfaces, feed mold in drywall, and rust nearby metal. I’ve seen baseboards swell and paint peel in laundry rooms where the door stayed shut and make-up air was poor.
If you have a gas dryer, starved air can worsen combustion and, in the wrong conditions, contribute to carbon monoxide risks—especially if a gas water heater shares the room. Even with electric dryers, poor airflow means longer dry times and higher bills. The right answer to the door question keeps your home drier, safer, and your clothes finishing on the first pass.
Step-by-Step Guide
Step 1: Identify your dryer and room situation
Not all setups behave the same. Start by noting whether your dryer is vented (4-inch duct to outdoors) or ventless/condensing. Also check if it’s gas or electric and measure the room. You might find lint alarm for dryers helpful.
- Vented dryers move 150–200 CFM to the outside and need make-up air from the room or grilles.
- Ventless/condensing or heat-pump dryers don’t exhaust outdoors, but they release heat and still need room air to operate efficiently.
- Small rooms or closets (under ~200 cubic feet) need more intentional make-up air than a full-size laundry room.
If you have a gas dryer or any combustion appliance sharing the room, treat make-up air as non-negotiable.
Step 2: Check and create make‑up air paths
Look at the door and surrounding walls. A 1-inch undercut on a 30-inch door yields about 30 square inches of gross opening (less in actual free area). Many manufacturers suggest providing roughly 60–120 square inches of free area via grilles or a louvered door for closet installations.
- If your door has no undercut and no louvers, crack it open during drying or add a transfer grille (for example, a 6×12-inch grille provides ~40–60 square inches of free area depending on the louver).
- Place two grilles (high and low) if the dryer is in a closet; it encourages better air movement.
- Keep pathways clear. Piles of laundry up against a louvered door can cut airflow dramatically.
Rule of thumb: If the door gets pulled firmly shut or you feel strong suction, the room is too tight.
Step 3: Verify and optimize the exhaust
Leaving the door open won’t fix a bad vent. Inspect the duct from dryer to exterior.
- Use smooth-walled 4-inch metal duct, shortest route possible. Aim for an equivalent length under ~35 feet (each 90° elbow counts as ~5 feet).
- Check the exterior hood while the dryer runs. You should see a strong, steady stream and a fully open damper.
- Clean the lint screen every load and the duct at least annually. Lint buildup is the top ignition factor in dryer fires.
If airflow is weak with the door open, you need vent cleaning or re-routing before worrying about door position.
Step 4: Manage heat and humidity in the space
Even when vented, dryers warm the room as they draw make-up air from the house. In very small rooms, you may notice temperature spikes. You might find dryer vent hose helpful.
- For vented dryers in tiny rooms: leave the door open or add grilles so the dryer isn’t starved for air.
- For ventless/condensing or heat-pump units: crack the door or provide room ventilation to avoid creating a hot box; these machines can raise room temperature several degrees over a cycle.
- If the laundry shares space with a bathroom, running an exhaust fan during drying can help keep humidity down.
Watch for foggy windows, musty smells, or damp walls—signs the room needs more ventilation.
Step 5: Address special cases (gas dryers and shared utility rooms)
Gas dryers need adequate air for combustion in addition to airflow for drying. If a gas water heater or furnace shares the room:
- Do not rely on a tightly closed door; provide permanent openings sized per the appliance manuals.
- Install a carbon monoxide alarm in the adjacent space and test it regularly.
- Avoid conditions that cause backdrafting (strong exhaust fans running simultaneously in a tight house).
When in doubt, err on the side of more make-up air and door open when running.
Step 6: Test your setup like a pro
Turn the dryer on with a warm load. Then:
- Feel airflow at the exterior vent; strong and warm is good.
- Hold a tissue near the undercut or grille—there should be gentle, not roaring, pull.
- Time your cycles. If a normal mixed load takes much over 50–60 minutes with a modern unit, airflow may be restricted.
Make one change at a time (open the door, then add a grille, etc.) and retest. The right combination balances noise control, efficiency, and safety. You might find dryer safety kit helpful.
Expert Insights
What I see most in the field is people closing a laundry closet door to quiet the dryer and accidentally starving it for air. The quick clue: the door is hard to open while the dryer runs, and dry times creep past an hour. The fix isn’t fancy—provide real make-up air. A louvered door or two transfer grilles (one high, one low) totaling roughly 60–120 square inches of free area is typical for a single dryer in a closet. A 1-inch undercut helps but usually isn’t enough by itself in tight homes.
A common misconception is that closing the door “traps heat” and helps drying. The opposite is usually true. Restricted make-up air reduces drum airflow, raises exhaust temperature, and slows moisture removal. Another misconception: ventless dryers don’t need ventilation. They still dump heat into the room; in a small space, that heat can make the dryer throttle down to protect itself.
Pro tips: keep the duct as straight and short as you can, cap the equivalent length near 35 feet, and use smooth metal—no foil flex if you can avoid it. Outside, make sure the hood damper swings freely. During a cycle, go feel the outdoor exhaust; it should be assertive. If you have a gas dryer or water heater nearby, install a carbon monoxide alarm and ensure the room isn’t under heavy negative pressure when the dryer runs. Door position matters, but airflow quality matters more.
Quick Checklist
- Confirm dryer type (vented vs. ventless, gas vs. electric).
- Measure door undercut and note any grilles or louvers.
- Crack the door during a cycle and see if dry time improves.
- Inspect duct: smooth 4-inch metal, minimal bends, clean annually.
- Check exterior hood for strong airflow and a freely moving damper.
- Add transfer grilles or a louvered door to provide 60–120 sq in free area.
- Keep combustibles and laundry off the door and return air openings.
- Install and test a CO alarm if you have a gas dryer or gas appliances nearby.
Recommended Tools
Recommended Tools for should you leave the laundry room door open when running a dryer
Frequently Asked Questions
Is it bad to keep the laundry room door closed while the dryer runs?
It’s fine if the room has adequate make‑up air via a louvered door, grilles, or a generous undercut. In a tight space with no openings, closing the door can starve the dryer for air, extend dry times, and increase heat and lint buildup. If you’re unsure, run a load with the door open; if it finishes faster, add permanent airflow openings.
Do gas dryers need the door open more than electric models?
Gas dryers need air for combustion and for drying, so they’re more sensitive to tight rooms. If your laundry area is small or shares space with a gas water heater or furnace, don’t rely on a sealed door—provide permanent openings or leave the door open during cycles. A carbon monoxide alarm in the adjacent area is a smart addition.
How big should the make‑up air opening be for a closet dryer?
Manufacturer specs vary, but a common range is 60–120 square inches of free area, split between high and low grilles. A 1-inch undercut on a 30-inch door offers roughly 30 square inches gross and less in effective free area, so it often isn’t enough alone for a tight closet. Always check your model’s installation guide for exact requirements.
What about ventless or heat‑pump dryers—should I leave the door open?
Ventless dryers don’t exhaust outdoors, but they release heat into the room and still need makeup air for internal airflow. In small rooms, crack the door or add a grille to avoid excessive heat buildup that can slow performance. If the room feels sauna-like after a cycle, it needs more ventilation.
Will leaving the door open make the house more humid?
A properly vented dryer sends moisture outside, so humidity impact inside should be small. If you notice humidity or condensation indoors, that’s a red flag for a restricted or leaky exhaust or a ventless unit in a small space. Improve the vent and consider using a bathroom-style exhaust fan near the laundry during cycles.
Can closing the door cause a fire risk?
The bigger fire risk is lint buildup in a restricted vent, but starving the dryer for air can raise temperatures and stress the machine. Keep the vent clean and short, provide adequate makeup air, and avoid kinks and foil flex duct. If the door must be kept closed for noise, add grilles or a louvered door rather than relying on a tight seal.
Is it okay to crack a window instead of leaving the door open?
Yes, a cracked window can supply makeup air in a pinch, especially in very tight homes. It’s not as convenient as a permanent solution, and in winter or summer it can affect comfort, but it works. For everyday use, install grilles or a louvered door so you don’t have to remember the window.
Conclusion
Door open or closed isn’t a cosmetic choice—it’s about airflow. If the laundry room has generous make‑up air through a louvered door, grilles, or a solid undercut, feel free to close the door. If the space is tight, the easiest fix is simple: open the door during cycles or add 60–120 square inches of free area. Next steps: check your vent for strong outdoor flow, clean the duct, measure your door gap, and plan a transfer grille if needed. Get the airflow right and you’ll dry faster, avoid moisture headaches, and keep the machine running safer for longer.
Related: For comprehensive information about Ventisafe, visit our main guide.