According to the U.S. Department of Energy, drafts, air leaks, and poor insulation can increase your energy bill by up to 20% every single month. If you add up all the tiny gaps around the average home’s doors and windows, it is the equivalent of leaving a window wide open all winter long.[1]
You do not need to replace your existing windows or hire a general contractor to fix this. For less than $30 at your local hardware store, you can eliminate the vast majority of these leaks in a single afternoon. In this guide, we will show you exactly how to hunt down invisible drafts and the fastest, cheapest ways to seal them up.
1. The “Incense Test”: Finding Invisible Leaks
Before you start applying tape and caulk, you need to know exactly where the air is escaping. You can hire a professional to do a pressurized “blower door test,” or you can do it yourself for pennies using the Incense Test.
How to perform the test:
- Wait for a cool, windy day.
- Turn off your HVAC system so internal fans are not moving the air.
- Light a stick of incense (or a long lighter) and hold it about two inches away from the edges of your window frames, door hinges, and the threshold at the floor.
- Move the smoke slowly along the perimeter. If the smoke suddenly blows horizontally or dissipates rapidly, you have found an active draft. Mark the spot with a piece of painter’s tape.
2. Sealing Door Drafts
Exterior doors are massive culprits for heat loss. Because they are opened and closed constantly, the factory seals wear down quickly. You need to address both the perimeter (the frame) and the threshold (the floor).
The Perimeter: V-Strip Weatherstripping
Adhesive foam tape is cheap, but it degrades quickly and can make the door hard to close. Instead, buy a roll of V-strip (also known as tension seal) weatherstripping. This is a V-shaped strip of plastic or metal. You stick one side to the door frame. When the door closes, it presses against the “V,” creating a firm, airtight tension seal that lasts for years.
The Bottom: Slide-on Door Sweeps
If you can see daylight under your front door, your heater is fighting a losing battle. The easiest fix is a slide-on door sweep. These are U-shaped pieces of vinyl with rubber fins on the bottom. You simply cut it to the width of your door with scissors, open the door, and slide it onto the bottom edge. No drilling or screws required.
3. Draft-Proofing Windows
Windows can leak air from the moving sashes, or from the point where the wooden frame meets the drywall. Here are two fast solutions:
Temporary Fix: Rope Caulk
If the draft is coming from the tracks where the window slides up and down, you cannot use permanent caulk without sealing the window shut forever. Instead, buy a $5 roll of rope caulk (often called mortite). It feels like modeling clay. You simply unroll a strip, press it into the drafty cracks with your thumb, and leave it there for the winter. In the spring, you pull it right off; it leaves no sticky residue behind.
Permanent Fix: Clear Silicone
If the draft is coming from the gap between the window trim and the wall, the original builder’s caulk has likely cracked. Buy a tube of 100% clear silicone caulk. Run a thin, steady bead along the crack, then smooth it out with a wet finger. It dries invisible and permanently stops the air leak.
4. Damage-Free Options for Renters
If you rent your home, your landlord likely will not allow you to apply caulk or install heavy-duty hardware. Here is how to stop drafts without losing your security deposit:
- Thermal Curtains: Buy heavy, thermally lined curtains and ensure they extend a few inches past the window frame on all sides. When closed at night, they act as an insulated blanket against the cold glass.
- Draft Dodgers (“Door Snakes”): Instead of installing a permanent door sweep, buy a fabric draft dodger filled with sand or rice. You simply lay it on the floor against the crack at the bottom of the door.
- Window Shrink Film: Window insulation kits cost about $15. You use double-sided tape to attach a clear plastic sheet over the entire window frame, then use a hair dryer to shrink the plastic until it is tight as a drum. It creates an airtight pocket of insulating air over the window, and peels off cleanly when your lease is up.
Frequently Asked Questions
Will weatherstripping damage my paint?
Most modern adhesive-backed weatherstripping (like foam or rubber tape) is safe for fully cured paint. However, if the paint is old or chipping, removing the tape later might pull some paint with it. To be safe, test a small 1-inch piece in a hidden corner first.
Should I seal the weep holes on my windows?
Absolutely not. The small rectangular holes at the bottom of modern vinyl or aluminum windows are “weep holes.” They are designed to let rainwater drain out of the window tracks. If you plug them with caulk to stop a draft, your window frame will fill with water, leading to mold and internal wall rot.
Are draft-proofing kits worth the money?
Yes. A standard roll of V-strip weatherstripping and a tube of caulk might cost $25 total, but they can easily save you $100+ over a single brutal winter. It is one of the fastest return-on-investments in home maintenance.
