How can I identify drafts around my windows and doors?

You can identify drafts by feeling for cold air around the edges of windows and doors, or by using a lit candle or incense stick to see if the flame flickers. Another method is to turn off the lights and check for light shining through gaps.

What materials are best for sealing windows and doors?

The best materials include weatherstripping (foam tape, V-strips, felt, vinyl, magnetic), caulk (silicone or latex), and expanding foam for larger gaps. Choose materials rated for exterior use and compatibility with the window/door material.

How do I prepare my windows and doors before sealing them?

Inspect the areas around the windows and doors, removing old caulk, dirt, and debris. Make sure the surfaces are clean and dry to ensure proper adhesion of the sealing materials; sanding may also be needed.

What's the best way to seal gaps and cracks in windows and doors?

For small gaps, apply caulk in a continuous bead, smoothing it for a clean finish. For larger gaps, use expanding foam designed for windows and doors, being careful not to overfill, or fill the gaps with backer rod before caulking. Weatherstripping is ideal for sealing movable parts.

What are the potential energy savings from sealing windows and doors?

Sealing air leaks can reduce heating and cooling needs by as much as 40% in older homes, leading to significant energy savings, potentially up to 10-15% on annual energy bills. This also increases comfort by maintaining consistent temperatures and reducing drafts and can save homeowners around £40 annually.

Seal Windows & Doors

By Home Sidekick Team May 25, 2025 8 min read 1521 words

windowsdoorssealingweatherstrippingcaulkenergy efficiencydiyhome improvement

Why Seal Windows and Doors?

Drafty windows and doors aren't just uncomfortable; they're a drain on your wallet and the environment. Air leaks allow heat to escape in the winter and cool air to seep out during the summer, forcing your HVAC system to work harder and driving up energy bills. According to the EPA, homeowners can save an average of 15% on heating and cooling costs by air sealing their homes and adding insulation in attics, floors over crawl spaces and basements. Beyond energy savings, sealing windows and doors enhances comfort by eliminating drafts, reducing noise pollution, and preventing the entry of dust, pollen, and pests. This comprehensive guide will walk you through the process of identifying and sealing leaks in your windows and doors, providing practical tips and actionable advice to improve your home's energy efficiency and comfort.

Identifying Air Leaks

Before you start sealing, it's crucial to identify where the air leaks are occurring. Here are a few methods to help you pinpoint those sneaky drafts:

The Hand Test: On a cold or windy day, simply walk around your home and feel for drafts around windows and doors. Pay close attention to the edges of the frames, the meeting rails of windows, and the bottom of doors.
The Incense Test: Light an incense stick and hold it near windows and doors. Watch the smoke. If the smoke wavers or is drawn towards a particular area, it indicates a draft.
The Paper Test: Place a piece of paper between the door or window and its frame. Close the door or window. If you can easily pull the paper out, there's a leak. Repeat this test at various points around the perimeter.
Visual Inspection: Examine the caulk and weatherstripping around your windows and doors. Look for cracks, gaps, or signs of deterioration.

Once you've identified the leaky areas, you can move on to the next step: gathering your supplies.

Essential Materials and Tools

To effectively seal your windows and doors, you'll need the right tools and materials. Here's a comprehensive list:

Caulk: Choose a high-quality, paintable caulk that is specifically designed for exterior use. Silicone-based caulk is excellent for its flexibility and water resistance [24]. Consider the color of your trim when selecting caulk. You'll likely need about half a cartridge per window or door, and four cartridges for the foundation sill [9].
Weatherstripping: Weatherstripping comes in various materials and styles, including foam tape, V-strips, and felt. Choose the type that is best suited for the specific area you're sealing.
Caulking Gun: A caulking gun is essential for applying caulk smoothly and evenly. Opt for a gun with a thumb release to prevent excess caulk from oozing out [2].
Utility Knife or Scraper: Use a utility knife or scraper to remove old caulk and weatherstripping.
Putty Knife: This is helpful for scraping away stubborn caulk residue.
Painter's Tape: Painter's tape can help you create clean, even caulk lines.
Cleaning Supplies: You'll need a cloth, cleaning solution (such as white vinegar or a degreaser), and possibly a solvent to clean the surfaces before applying caulk or weatherstripping.
Measuring Tape: A measuring tape is essential for measuring gaps and cutting weatherstripping to the correct length.
Scissors or Utility Knife: Use scissors or a utility knife to cut weatherstripping.
Heat Gun or Hair Dryer: A heat gun or hair dryer is useful for shrinking plastic window film, if you choose to use it.
Foam Backer Rod (Optional): If you have large gaps (greater than 1/4 inch) to fill, use a foam backer rod before applying caulk [14,21].

Sealing Windows: A Step-by-Step Guide

Sealing windows involves a combination of caulking and weatherstripping. Here's a detailed guide to help you through the process:

Step 1: Prepare the Surface

Begin by cleaning the window frame and surrounding area. Remove any dirt, dust, old caulk, and loose paint [8,9,23]. Use a utility knife or scraper to remove old caulk, and a putty knife for stubborn residue. Ensure the surface is dry before proceeding [9].

Step 2: Apply Painter's Tape (Optional)

If you want to achieve a clean, professional-looking caulk line, apply painter's tape along both sides of the joint you're about to caulk [8,23]. This will create a crisp, even edge.

Step 3: Caulk the Gaps

Load your caulk tube into the caulking gun. Cut the tip of the caulk tube at a 45-degree angle, making sure the opening is the same size as the joint you're sealing [8]. Apply a steady bead of caulk along the joint, holding the gun at a consistent angle [9]. Try to apply the caulk in one continuous stream, avoiding stops and starts [9]. Release the pressure lever slowly as you finish a bead to avoid dripping [14]. If you have large gaps (greater than 1/4 inch), insert a foam backer rod before caulking [14,21].

Step 4: Smooth the Caulk

After applying the caulk, smooth it with a wet finger or a caulking smoothing tool [2]. This will push the caulk into the crack and create a watertight seal [9].

Step 5: Remove Painter's Tape (If Used)

If you used painter's tape, remove it immediately after smoothing the caulk. Pull the tape away at a 45-degree angle to avoid damaging the caulk line [8].

Step 6: Apply Weatherstripping

Apply weatherstripping to the moving parts of the window, such as the sashes. Measure the length of the area you need to seal and cut the weatherstripping accordingly [12]. Remove the backing from the weatherstripping and adhere it to the window frame or sash. Ensure the weatherstripping seals tightly when the window is closed [1].

Step 7: Allow to Dry and Cure

Allow the caulk to dry and cure completely according to the manufacturer's instructions. This may take 24-48 hours [9].

Sealing Doors: A Comprehensive Approach

Sealing doors requires a slightly different approach than sealing windows. Here's a step-by-step guide to effectively seal your doors:

Step 1: Inspect the Door

Examine the door frame and threshold for gaps and cracks. Pay close attention to the bottom of the door, where drafts are common.

Step 2: Weatherstrip the Frame

Apply weatherstripping around the perimeter of the door frame. Use a type of weatherstripping that is appropriate for doors, such as foam tape, V-strips, or magnetic weatherstripping [18]. Make sure the weatherstripping creates a tight seal when the door is closed [1].

Step 3: Install a Door Sweep or Threshold

Install a door sweep or threshold at the bottom of the door to seal the gap between the door and the floor. A door sweep attaches to the bottom of the door, while a threshold replaces the existing sill [18,19]. Choose a product that is appropriate for your door and flooring type [18].

Step 4: Caulk Any Remaining Gaps

Use caulk to seal any remaining gaps or cracks around the door frame. [12] Apply the caulk smoothly and evenly, and smooth it with a wet finger or caulking tool [12].

Step 5: Address Keyholes and Letterboxes

Don't forget to seal keyholes and letterboxes, as these can also be sources of drafts. Use keyhole covers and letterbox flaps or brushes to prevent air leakage [10,4].

Choosing the Right Weatherstripping

With so many types of weatherstripping available, it can be challenging to choose the right one for your needs. Here's a quick guide to some common types:

Foam Tape: Easy to install and suitable for irregular gaps. Inexpensive but may not be as durable as other options [17].
V-Strips (Tension Seals): Durable and effective for sealing the sides of windows and doors. Made from plastic or metal and create a tight seal [17].
Felt Weatherstripping: Inexpensive and easy to apply, but not very durable or effective at blocking airflow [13].
Magnetic Weatherstripping: Provides a tight seal and is particularly effective for metal windows. More expensive than other options [17].
Tubular Rubber and Vinyl: Durable and flexible, suitable for high-traffic areas like door bottoms and window sashes [17].

Consider the location and the size of the gap you need to seal when choosing weatherstripping.

Additional Tips for Energy Efficiency

Sealing windows and doors is a great start, but here are a few additional tips to maximize your home's energy efficiency:

Insulate Walls and Attics: Proper insulation is crucial for preventing heat loss.
Use Thermal Curtains: Thermal curtains can help to block drafts and reduce heat loss through windows [10].
Seal Air Ducts: Leaky air ducts can waste a significant amount of energy.
Consider Window Film: Insulating window film can add an extra layer of protection against drafts [10].
Close Doors to Unused Rooms: Closing doors to rooms you don't use can help to conserve energy [10].

Conclusion: A More Comfortable and Energy-Efficient Home

Sealing windows and doors is a simple yet effective way to improve your home's energy efficiency, reduce your energy bills, and enhance your comfort. By following the steps outlined in this guide, you can identify and seal air leaks, creating a more comfortable and energy-efficient living environment. The next step is to gather your materials and tools and set aside a weekend to tackle this project. Your wallet and the environment will thank you!