A drafty door or window doesn’t just make a room feel colder — it forces your heating and cooling system to work continuously to compensate for air that’s leaking out (or in) around gaps you likely haven’t noticed. The good news is that weatherproofing is one of the most cost-effective energy projects available: most of the fixes below cost under $50 total and can be done in an afternoon, with no special skills or tools required.
How to Find Where You’re Actually Losing Air
Before buying anything, it helps to identify your specific problem areas rather than guessing:
The hand test
On a windy or cold day, slowly run your hand around the edges of door and window frames, electrical outlets on exterior walls, and where pipes enter your home. A noticeable temperature change or airflow is a clear sign of a leak at that spot.
The candle or incense test
Hold a lit candle or incense stick near the edges of a closed window or door. If the flame or smoke flickers or bends noticeably, air is moving through a gap at that point — this is a simple, low-cost way to pinpoint leaks that aren’t obvious by touch alone.
The paper test (for doors specifically)
Close a door on a piece of paper. If you can pull the paper out easily without resistance, the door isn’t sealing tightly enough at that point, and weatherstripping or a threshold adjustment is likely needed.
A professional energy audit
Many utilities offer free or low-cost home energy audits that use a blower door test and sometimes infrared imaging to identify every air leak in your home systematically — worth considering if you want a comprehensive picture before investing in bigger projects, rather than relying solely on manual spot-checks.
Drafts around windows and doors are only part of the picture. Our guide to how to save on heating without freezing covers other ways to reduce heat loss, improve comfort, and prioritize low-cost improvements before investing in larger upgrades.
The U.S. Department of Energy provides additional guidance on weatherizing your home, including air sealing and insulation. A professional assessment can help identify less obvious leaks and determine which improvements are most appropriate for your home.
Weatherproofing Doors: Step by Step
Step 1: Install weatherstripping around the door frame
Weatherstripping comes in several types — adhesive-backed foam, felt, V-strip (tension seal), and door-frame-mounted metal or vinyl strips. Foam is the cheapest and easiest for a DIY job; V-strip tends to hold up longer and seals more tightly. Clean the frame surface, measure and cut strips to fit, and apply along the sides and top of the door frame where the door meets it when closed.
Step 2: Add or replace the door sweep
The gap under an exterior door is one of the most significant, commonly overlooked sources of draft. A door sweep — a strip with a flexible seal that attaches to the bottom of the door — closes this gap. Installation typically takes just a few minutes with a screwdriver.
Step 3: Check and adjust the threshold
If a door still doesn’t seal well at the bottom even with a sweep installed, the threshold itself (the strip on the floor beneath the door) may be worn or improperly adjusted. Many adjustable thresholds have screws that raise or lower the seal — a small adjustment can close a persistent gap without needing a full replacement.
Step 4: Seal the frame itself with caulk
Beyond the moving parts (weatherstripping, sweep), check where the door frame meets the surrounding wall — gaps here (visible from inside or by removing interior trim) can be sealed with caulk or expanding foam for a permanent fix.
Once you have sealed the obvious gaps, check other parts of the home where air can leak through the building envelope. Our guide to 20 real ways to lower your electric bill covers additional improvements, from heating and cooling adjustments to lighting and appliance habits.
Weatherproofing Windows: Step by Step
Step 1: Caulk any gaps in the window frame
Where the window frame meets the wall, and any visible cracks in older wood frames, can be sealed with a paintable caulk. This is a permanent fix, best done in mild weather when caulk cures properly (extreme cold or heat can affect the seal).
Step 2: Add weatherstripping to operable sections
For windows that open (double-hung, sliding, casement), apply weatherstripping to the moving sashes similarly to a door — foam or V-strip along the edges where the window meets its frame when closed.
Step 3: Apply removable window insulation film for winter
A clear plastic film, applied with double-sided tape and shrunk tight with a hairdryer, creates an additional insulating air pocket over the entire window. This is especially effective for older single-pane windows and can be removed each spring, making it a genuinely low-commitment seasonal fix rather than a permanent alteration.
Step 4: Use heavy or thermal curtains strategically
Thermal-lined curtains, closed at night and during the coldest parts of the day, add a meaningful insulating layer over the entire window area — not a substitute for sealing actual air leaks, but a complementary layer that reduces radiant heat loss through the glass itself.
Window drafts can affect comfort in summer as well as winter. For more ways to reduce cooling costs during hot weather, see our guide to how much it costs to run AC 8 hours a day. Sealing gaps can reduce unwanted air exchange, although it does not replace the need for adequate ventilation.
Step 5: Consider interior or exterior storm windows for persistent problem areas
For windows that remain drafty even after sealing and film, a storm window (interior or exterior mounted) adds a full additional glazing layer, meaningfully improving insulation without the cost of full window replacement — a reasonable middle step between DIY sealing and a major renovation project.
A Room-by-Room Priority Checklist
Rather than tackling your whole home at once, prioritize based on impact:
- Exterior doors used daily (front door, back door, garage entry) — highest priority, since these see the most wear on seals and the most frequent opening/closing.
- Windows in the rooms you use most — living room, bedroom, home office — where draft directly affects your day-to-day comfort and thermostat usage.
- Windows and doors on the side of the house facing prevailing winter winds, if you know your local wind patterns, since these see more pressure-driven air infiltration than sheltered sides of the home.
- Less-used rooms and doors last — guest rooms, secondary exterior doors — worth addressing eventually, but lower priority for your first weatherproofing pass.
If you work from home, pay particular attention to drafts in the room you use most. Our guide to energy-saving tips for working from home covers practical ways to manage heating, cooling, lighting, and computer equipment during the workday.
What This Actually Saves
While the exact savings depend heavily on how drafty your home was to begin with, air sealing around doors and windows is consistently cited by energy efficiency programs as one of the highest return-on-investment projects available for a typical home — largely because the fixes are inexpensive (often under $50-100 total for a full home) while directly reducing the amount of conditioned air your HVAC system has to continuously replace. Combined with the other heating and cooling strategies covered in our guide on [saving on heating without freezing] and [reducing your AC bill in summer], sealing air leaks addresses the root cause of a meaningful share of typical heating and cooling waste.
If you are also considering larger heating-system improvements, our guide to how much it costs to install a heat pump explains the main installation cost factors. Air sealing and insulation improvements may affect the heating and cooling load that a new system needs to handle, so consider the condition of your home’s envelope when planning upgrades.
Common Mistakes to Avoid
- Over-sealing without ventilation awareness. A small amount of natural air exchange is healthy for indoor air quality — the goal is eliminating obvious, wasteful drafts, not making a home completely airtight without any ventilation consideration (mechanical ventilation systems exist for genuinely airtight homes, but that’s a different, larger project than basic weatherproofing).
- Using the wrong weatherstripping type for the gap size. A gap that’s too large for standard foam weatherstripping will compress fully and stop sealing quickly — check the strip’s rated gap-size range before buying.
- Skipping the “why” behind a leak. If a door consistently won’t seal despite new weatherstripping, the underlying cause might be a warped door, settling foundation, or misaligned hinges — worth diagnosing rather than repeatedly replacing weatherstripping that keeps failing at the same spot.
Final Thoughts
Weatherproofing doors and windows is one of the rare home improvement projects that’s simultaneously cheap, fast, and genuinely high-impact — most of the fixes above cost well under $100 combined and can be completed in a weekend, with no permanent structural changes required beyond a bit of caulk. Start with your most-used exterior doors and the windows in your most-occupied rooms, and you’ll likely notice a difference in both comfort and your next few utility bills before moving on to any of the bigger structural projects further down your home’s overall efficiency wish list.