Sealing air leaks is the highest-leverage action most landfill neighbors can take—more bang for the buck than any purifier. A tight home keeps outdoor air out, reduces the load on your purifiers, and cuts energy costs. Here's how to do it systematically.
Start With a Detection Walk
On a cold, windy day, turn off all fans and the HVAC. Walk the perimeter of your home's interior. Hold your hand near door frames, window edges, outlet covers, and any penetrations. Better: hold a lit incense stick 2 inches from suspect areas—smoke deflection reveals air movement invisible to touch.
Pay special attention to: the attic hatch, areas behind knee walls, the band joist (where your floor meets the foundation wall), and any dropped soffits above cabinets.
Priority 1: Exterior Doors
Each exterior door has three potential leak zones: the threshold gap (under the door), the weatherstripping on three sides, and the door frame-to-rough-opening gap (often unfilled or with degraded silicone caulk Amazon). Address all three.
Keliiyo EPDM Weatherstripping — 66ft 2-Pack
Enough for 4–6 exterior doors. EPDM rubber holds up in all temperatures. Grid adhesive backing is significantly stronger than basic foam tape.
Check Price on AmazonWeather Stripping Kit with Door Sweep
Complete kit: 39ft weatherstrip + 43" door sweep Amazon for the gap under the door. One kit handles a full door 360°.
Check Price on AmazonPriority 2: Electrical Boxes
Every exterior-wall outlet and switch is a hole in your building envelope. Foam gasket insulators slip behind the cover plate and take about 90 seconds per outlet. This is one of the most underrated sealing tasks—in a typical house, unsealed outlets can account for 5–10% of total air infiltration.
Frost King Foam Outlet & Switch Sealers
Fire-retardant foam gaskets slip behind standard outlet and switch plates. Do your entire house in one afternoon.
Check Price on AmazonPriority 3: Window Perimeters
Caulk the perimeter where the window frame meets the wall—both inside and outside. Use paintable silicone or acrylic latex caulk for interior use. Replace cracked or missing caulk on exterior window trim.
DAP 18001 Latex Window & Door Caulk
Paintable, flexible acrylic latex caulk. Ideal for interior window perimeters, trim gaps, and corner joints. 40-year durability.
Check Price on AmazonPriority 4: Utility Penetrations
Every pipe, wire, and duct that passes through an exterior wall or floor is a potential air highway. Expanding foam sealant fills gaps around pipes and wires. For larger gaps (over 3 inches), use backer rod first, then caulk over it.
Great Stuff Gaps & Cracks Foam Sealant
Expanding polyurethane foam for pipes, conduit, wiring penetrations, and gaps under ½ inch. Cures airtight in 8 hours.
Check Price on AmazonMeasuring Your Results
After sealing, watch your PM2.5 monitor on a windy day from the landfill direction. Readings that previously spiked should be more stable. A 20–40% reduction in PM2.5 infiltration rate is achievable with thorough sealing, even without a professional blower door test.