Weatherstripping seals the moving parts of your house: doors, windows and the attic hatch. Air sealing closes the hidden gaps in the attic, walls and floors where most heated air actually escapes. Weatherstripping stops the drafts you can feel at a door. Air sealing stops the bigger leaks that cause those drafts, so most older homes need both.
Drafts tend to announce themselves in the first few weeks of the heating season. You feel a cool line of air under the front door, a breeze from the outlet by the couch and a chill dropping out of the attic hatch in the hallway. The natural first move is a trip to the hardware store for foam tape and a door sweep.
That is a good start, and it helps. But in an older home in Logan, Garland, Hillyard or the Fort Grounds in Coeur d'Alene, the drafts you feel at the door are often being pulled in by leaks you will never see from the living room. Knowing the difference between the two jobs helps you spend your weekend, and your budget, where it counts.
What does weatherstripping actually do?
Weatherstripping fills the gap between a moving part and its frame. Doors, operable windows and attic hatches all need a little clearance to open and close, and over time that clearance grows as wood shrinks, hinges sag and old seals flatten out.
Common types include foam tape, rubber or vinyl bulb seals, V-strip (tension seal) along window sashes, door sweeps along the bottom of a door and adjustable thresholds. All of them do the same basic thing: they press against the moving part when it closes so outside air cannot slip through the gap.
Weatherstripping is inexpensive, easy to install and very satisfying, because you feel the result right away. The U.S. Department of Energy notes that when windows are in good condition, updating them with steps like sealing air leaks, caulking and weatherstripping may be the most cost-effective way to improve comfort. Its limit is that it only covers the places that open and close.
What is air sealing, and where does it happen?
Air sealing closes the permanent gaps in the shell of the house: the holes, cracks and joints that were never meant to move. In an older home, the most important ones are usually in the attic, where they are out of sight and often buried under old insulation.
Builders call these attic bypasses, because they let warm air bypass the ceiling and flow straight into the attic. The usual suspects include:
- Gaps around recessed lights and ceiling light boxes
- Holes where plumbing stacks and vent pipes pass through the ceiling
- The open space around a chimney chase
- The tops of interior walls (top plates), where drywall and framing meet
- Holes drilled for wiring over the years
- The attic hatch or pull-down stairs themselves
- Dropped soffits over kitchen cabinets and bathroom ceilings
Attic Air Sealing closes those openings with materials matched to the gap: caulk for small cracks, expanding foam for larger holes and rigid materials with fire-rated sealant around chimneys and flues where required. Lower in the house, air sealing can also mean outlet and switch gaskets, caulk along baseboards and sealing where pipes and wires pass through exterior walls.
Why do the biggest leaks hide where you cannot see them?
Warm air rises. In winter, that simple fact turns your house into a slow chimney, a pattern called the stack effect. Heated air pushes up against the ceiling and finds every gap into the attic. As it leaves up high, the house replaces it by pulling cold outside air in down low.
That is why the drafts you notice are mostly at floor level: under doors, along baseboards and around lower outlets. Those are the intake points. The exits are overhead in the attic, and they are often the larger openings.
If you weatherstrip every door and window but leave the attic bypasses open, warm air keeps escaping overhead and the house keeps looking for ways to replace it. The drafts get smaller, but the heat loss continues. Seal the attic, and you take away much of the pull that was driving those floor-level drafts in the first place.
Why do drafts feel worse in Spokane and North Idaho homes?
The U.S. Department of Energy places Spokane County and Kootenai County in Climate Zone 5, a zone with cold winters and a long heating season. The stack effect gets stronger as the gap between indoor and outdoor temperatures grows, so the same leak that barely registers in October can feel like an open window by December.
Older housing adds to it. Story-and-a-half homes on the South Hill and around Sanders Beach have knee walls and sloped ceilings with plenty of hidden joints. Postwar ranches in Spokane Valley and Post Falls often have decades of wiring and plumbing holes punched through the top plates. Many homes have an attic hatch that is nothing more than a loose piece of drywall with no seal and no insulation on top.
Those gaps come with the age of the house, and in a climate this cold they are worth chasing down.
Myth vs. fact: weatherstripping and air sealing
Myth: If I weatherstrip the doors and windows, I have sealed my house.
Fact: Weatherstripping covers only the parts that open and close. The attic, walls and floors usually hold more total leakage, and those gaps need air sealing.
Myth: My house needs to breathe, so sealing it is a bad idea.
Fact: Air sealing targets unplanned leaks through cracks and holes. Planned ventilation, such as bath fans, kitchen exhaust and attic vents, stays in place and keeps doing its job.
Myth: More insulation in the attic will stop the drafts.
Fact: Air moves right through loose insulation. Sealing the gaps first and then insulating is what stops both the air movement and the heat flow.
Myth: Drafts mean I need new windows.
Fact: Sometimes they do, but windows in good condition often just need new weatherstripping and caulk. Check the attic and walls before you decide.
Myth: Air sealing is only for new houses.
Fact: Older homes usually have the most to gain, because they have had decades of holes drilled, framing settle and seals wear out.
What can you handle yourself this weekend?
There is plenty a homeowner can do with a caulk gun and an afternoon. These steps are worth doing no matter what else you plan.
- Replace worn door weatherstripping and sweeps. If you can see daylight around a closed exterior door, the seal is done.
- Add V-strip or foam to drafty window sashes. Focus on windows that rattle or let in a breeze when the wind blows.
- Caulk gaps along baseboards and window trim. Use a paintable caulk on interior trim.
- Seal and insulate the attic hatch. Add weatherstripping where the hatch rests and a piece of rigid insulation on top.
- Check exposed ductwork in unheated spaces. ENERGY STAR estimates that about 20% to 30% of the air moving through a typical duct system is lost to leaks, holes and poorly connected ducts. If you have ducts in a garage or attic, an HVAC professional can look at the connections.
Where it makes sense to call a professional is the attic floor itself. Finding bypasses under old insulation, working safely around wiring and chimneys and sealing gaps before topping up the insulation is slow, dusty work in a tight space, and doing it right matters.
How do air sealing and insulation work together?
Air sealing and insulation do different jobs. Sealing stops air from moving through the shell of the house. Insulation slows heat from passing through it. A wall or ceiling needs both to perform well, and the order matters: seal first, then insulate, because once new insulation is blown in, the gaps underneath are much harder to reach.
That is why we usually look at Attic Air Sealing and Blown-In Attic Insulation together. ENERGY STAR recommends R-60 for an uninsulated attic in Climate Zone 5, or R-49 when adding to 3 to 4 inches already there. Bringing the attic to that level on top of a sealed ceiling is one of the more effective upgrades for an older home. In closed exterior walls, Premium Injection Wall Foam fills the cavity and helps fill gaps around wiring and framing inside it.
ENERGY STAR estimates that homeowners can save an average of 15% on heating and cooling costs, or 11% on total energy costs, by air sealing and adding insulation in attics, floors over crawl spaces and accessible basement rim joists. Every house is different, so your results will vary, but comfort near doors and outside walls is usually the first change people mention.
So which one stops winter drafts?
Weatherstripping takes care of the drafts at your doors and windows, and it is worth doing this weekend. Air sealing goes after the hidden gaps that keep pulling cold air into an older home all winter long. Ask about air sealing at your free inspection with USA Insulation of Spokane-CDA, and we will check your attic and walls, show you photos of what we find and give you a written estimate for the work that will make the biggest difference.
