Seal Your Home Against Wildfire Smoke
A room-by-room checklist that helps you block the biggest air leak paths using materials you already own. Works in 30 minutes or less.
Leak Paths Ranked by Smoke Infiltration
Not all gaps are equal. This list ranks the most common ways smoke enters a typical home, from highest to lowest impact.
Unlocked or poorly sealed windows
Even a cracked window lets in a surprising amount of smoke. Old weatherstripping shrinks and pulls away over time. Check every window, especially on the windward side of your house.
Highest impactExterior door gaps (bottom and sides)
Door sweeps wear out. Gaps as small as 1/8 inch along the bottom edge act like an open window for fine smoke particles.
Highest impactGarage door perimeter
Garage doors rarely seal well. If your garage is attached, smoke enters there and migrates into the house through the connecting door and wall penetrations.
High impactBathroom exhaust fans (running or unsealed)
Fan covers without backdraft dampers pull outdoor air inward when fans are off. Running them during smoke events makes it worse.
Medium impactKitchen range hood venting outside
Like bathroom fans, range hoods without tight dampers allow smoke-laden air to flow backward into the kitchen.
Medium impactHVAC fresh-air intake or damper
Some systems bring in outdoor air by design. Close the fresh-air damper if your system has one. Check the manual or look for a lever on the intake duct.
Medium impactAttic hatch or pull-down stairs
Gaps around attic access points let smoke-laden air enter the ceiling cavity and work its way down through light fixtures and vents.
Medium impactDryer vent
Plastic dryer vent flaps often warp or stick open. Smoke enters through the vent hose and spreads through the laundry area.
Lower impactElectrical outlets and switch plates on exterior walls
Foam gaskets behind outlet plates cost almost nothing. Without them, each outlet is a small but real leak point.
Lower impactRecessed ceiling lights (IC-rated or not)
Non-IC-rated cans have ventilation holes that connect directly to the attic. Even IC-rated housings have small gaps at the trim ring.
Lower impactPet doors
Magnetic or flip-style pet doors rarely seal tightly. During smoke events, block them from the inside.
Lower impactMailbox slot or keyhole
Small but real. A flap cover or a piece of tape over the inside of the mail slot takes two seconds.
Lower impactRoom-by-Room Sealing Checklist
Work through each room. Mark items as sealed, not applicable, or skipped. Your progress saves automatically in this browser.
Your Sealing Summary
Complete the checklist above to see your personalized summary of sealed and remaining items.
What to Use When You Don't Have Weatherstripping
Most households have enough to block the biggest gaps. Here are substitutes ranked by effectiveness.
Towels or blankets
Roll a towel and press it along the bottom of a door. Hang a damp blanket over a doorway between rooms. Wet fabric catches more particles but works dry too.
Duct tape + plastic sheeting
Cover a window that won't be used with a cut-open garbage bag or painter's plastic. Tape all four edges. This seals the window completely for the duration of the event.
Pool noodle or pipe insulation
Slit a pool noodle lengthwise and press it against the bottom of a door or window sash. Pipe insulation tubes work the same way for narrower gaps.
Shower curtain or garbage bag
Hang a shower curtain over an open doorway to create a room you can keep cleaner. Tape a garbage bag over a bathroom fan cover from the inside.
Clothespins + fabric
Clip a piece of old t-shirt or pillowcase over a vent gringe. Not airtight but reduces airflow enough to slow smoke infiltration.
Silicone caulk (if time allows)
A $5 tube of caulk seals gaps around window frames, outlet boxes, and baseboards permanently. Do this before smoke season, not during.
If you can buy one thing
Self-adhesive foam weatherstripping tape costs $3–$5 at any hardware store. A single roll seals 2–3 doors or 4–5 windows. Door sweeps cost $5–$8 and take 10 minutes to install with a screwdriver. These two items cover the three highest-impact leak paths on the ranking list.
Common Mistakes That Make Things Worse
Good intentions can backfire. Here are the errors people make most often during smoke events.
Blocking required egress windows
Bedroom windows that serve as fire exits must remain operable. Use removable tape and plastic instead of nailing or permanently sealing them. If you need to leave fast, you need to get out fast.
Sealing bathroom exhaust fans permanently
Cover fan grilles during the smoke event, but remove the cover within a few hours after outdoor air improves. Trapped moisture leads to mold, which is its own health problem.
Running bathroom or kitchen fans during smoke events
These fans pull outdoor air inside. Turn them off unless you're dealing with a steam shower or cooking smoke. Even then, open a window briefly and close it fast, or skip the fan entirely.
Using ozone generators indoors
Ozone does not remove smoke particles and is harmful to lungs. The EPA and California Air Resources Board both warn against using ozone generators in occupied spaces.
Ignoring the garage-to-house connection
People seal the front door perfectly but forget the door from the garage into the house. Seal both sides of that door and the garage door perimeter.
Staying sealed during a CO or gas alarm
If your carbon monoxide detector or gas alarm sounds, open windows and doors immediately and get outside. Sealing the house traps dangerous gases inside.
Questions People Ask During Smoke Season
Does sealing my house actually lower indoor smoke levels?
Research from Colorado State University and EPA field studies shows that closing and sealing a typical single-family home reduces indoor PM2.5 concentrations by 40–60% compared to leaving windows and doors unsealed. The benefit is greatest in the first 2–6 hours of a smoke event.
What if I don't have any weatherstripping or tape at all?
Towels and duct tape work in a pinch. Roll a towel against the bottom of a door. Cover a window with a garbage bag taped at the edges. These are temporary but they meaningfully slow smoke entry. Old blankets hung over interior doorways also help create a cleaner room inside the house.
Should I seal bathroom vents and kitchen range hoods?
Cover exhaust fan grilles with plastic and tape during the event. Remove the covering within a few hours after outdoor air quality improves. Never seal a gas water heater closet or any combustion appliance vent. Those must stay open for safety.
When is sealing not enough and I should evacuate?
Leave if officials issue an evacuation order. Leave if smoke is so thick you can't see across the street. Leave if anyone in the home has worsening breathing problems despite sealing. And leave if the event lasts more than 2–3 days and you have no HEPA air purifier. Sealing buys time. It is not a long-term solution.
How do I know if my home is sealed well enough?
Light a stick of incense on both sides of a door or window. Watch the smoke. If it moves toward or away from the gap, air is flowing through. This simple test shows you exactly where the remaining leaks are.
How often should I redo this checklist?
At the start of each smoke season, and any time you move, renovate, or notice new drafts. Doors and windows shift over time. Weatherstripping dries out. What was sealed last year may have gaps this year.
Can I use a box fan with a furnace filter instead of sealing?
A DIY box fan filter (a MERV 13 filter taped to the back of a box fan) helps clean air inside an already-sealed room. But sealing first makes it work much better. The two strategies together are stronger than either one alone.
A Real Scenario: Smoke Expected by Evening
Check the forecast and AQI
Go to airnow.gov or your local air quality district page. If smoke is expected within 6–12 hours, start sealing now. Don't wait until the sky turns orange.
Seal the three biggest leak paths
Close all windows. Roll towels against exterior door bottoms. Tape over any window that won't be opened. These three steps alone cut smoke infiltration roughly in half.
Seal vents and secondary paths
Cover bathroom fan grilles with plastic. Tape the garage door edges. Close the attic hatch gap with a towel or foam board.
Pick a clean room and add a filter
Choose one room where everyone can stay. Close the door. If you have a box fan, tape a furnace filter to the back and run it on low. This room now has the cleanest air in the house.
Monitor and adjust
Check AQI every 1–2 hours. If indoor air feels smoky, check for missed gaps. If AQI exceeds 200 for more than a few hours and you have no air purifier, consider leaving for a public clean-air shelter.