Sealing exterior window frames is essential to keeping your home at a comfortable temperature and increasing the energy efficiency of the house, lowering energy costs. It’s also necessary for preventing damage to the windows and building’s structure. To properly seal a window frame outside, you’ll need to choose the right type of caulk, prime the surface, and apply the material.

Below, we’ve outlined why this home maintenance task is so important while also giving you the tools, tips, and instructions so you can do it yourself.


Why Is Sealing Window Frames Important?

Exterior window frames need to be sealed as it is essential step to keeping your home comfortable and maintained. These sealants are responsible for keeping outside air out and inside air in while also preventing water infiltration. Skipping this home improvement job can result in high energy costs, water damage, premature deterioration of the windows, and drafts.

However, it isn’t enough to simply throw sealant on the window and call it a day. Homeowners need to use the right material and methods to provide a proper seal.

Source: canva.com

How Can You Tell If Your Window Frames Need to Be Resealed?

Homeowners should check their exterior windows for issues with the sealant every one to two years. Physical wear, including cracks and dry caulk, could be obvious after a simple visual check. You should check the spot where the frame of the window meets the wall and the intersections of the window. Other signs you’ll need to reseal your exterior windows include drafts, window fogginess, leaks, and condensation.

Read Also: How to repair window seal


Types of Caulk For Sealing Exterior Windows

It’s important to use the right caulk for your windows. Not all are designed to withstand the elements, and choosing the wrong one for the exterior of your home could cause damage. Here are some of the most common types of sealant and advice for using them around your windows:

1. Acrylic Latex Caulk

Acrylic latex caulk is water-based, meaning there are no harmful chemical components, and it’s simple to clean up. This type of sealant can be painted or pre-tinted to match existing color schemes, although it is not especially weather- or temperature-resistant. As a result, it’s best suited for use in the home, not for exterior windows.

2. Butyl Rubber Caulk

Butyl rubber caulk is commonly used to seal gutters, flashings, roof repairs, and similar areas. It’s specifically designed for metal, but it can be a great option for exterior windows, too. Butyl rubber caulk is adhesive, weather-resistant, and temperature-resistant, meaning it can stand up to the elements and provide a flexible yet durable seal.

3. Latex Caulk With Silicone

Latex caulk with silicone has improved water resistance and is recommended for indoor and outdoor applications. It’s a solid choice for exterior windows as it’s noted for its paintability and durability, especially in areas that see four seasons.

4. Masonry Repair Caulk

Sealing seams in masonry, stucco, and concrete slabs is easy with this flexible caulk. Some are latex-based, while others are solvent-based and require mineral spirits to clean up.

5. Polyurethane Caulks

Polyurethane caulks are based on a solvent. This makes them extremely effective. Most common housing materials can be bonded with polyurethane caulks, making them a top choice for sealing exterior windows. However, when exposed to ultraviolet (UV) light, they can degrade over time.

It’s important to note that working with polyurethane caulks tends to be more difficult than working with silicone caulks. If your new to caulking, you might want to choose an easy-to-work with sealant.

6. Pure Silicone Caulk

Pure silicone caulk is appropriate for high-moisture areas such as tubs and showers, but it can be used with windows. It doesn’t accept paint, although it comes in various colors to suit your needs. However, this option can be a bit more expensive than the others.


7 Steps To Properly Seal Window Frames Outside

If it’s time to seal your outdoor window frames, you’ll have to gather the right materials first.

What You’ll Need

  • Putty knife or scraper
  • Retractable razor-blade scraper
  • Long nail or wire hanger
  • Caulk
  • Caulk gun
  • Small plastic spoon or wooden craft stick
  • Cloth
  • Rubbing alcohol
  • Blue painter’s tape
  • Water

Steps To Follow

1. Select The Right Sealant

Before you can get started, you need to make sure you have the right caulk on hand. Consider your home’s material, the elements the sealant will be exposed to, and whether or not you will need to paint over the caulk.

2. Remove Any Existing Sealant

Remove old caulk before applying new caulk. You can use a retractable razor-blade scraper to prepare the surfaces to remove the existing caulk.

Depending on the age of the caulk job and the positioning of the caulk bead, a putty knife or scraper may also be useful. Use a cloth and rubbing alcohol to wipe the surfaces.

3. Prepare The Surface

Mask off both surfaces using blue painter’s tape. Make sure the tape is straight. It’s better to use a few longer pieces of tape rather than small pieces.

The joint will appear best if you tape in a pretty thin line, around 1/4 inch wide. The caulk bead may need to be broader, up to 3/8 inch, for uneven joints.

Make sure to firmly press down on the inside edges of the tape. The idea is to seal these borders so that caulk does not leak underneath, which can be done using a wooden craft stick or your fingernail.

4. Apply Backer Rods For Wider Gaps

If you have wider gaps between the frame itself and the wall, you can use backer rods to support you during the application process. These can help to control the sealant thickness and make sure the right amount of caulk is applied.

5. Apply Your Sealant or Caulk

To open the caulk tube, cut the tip of the nozzle at a 45-degree angle with a utility knife. You will also need to use a long nail or wire into the nozzle to puncture its seal. To guarantee a smooth flow of caulk, you can poke the seal a few times.

Caulk should be applied at a 45-degree angle between horizontal and perpendicular. Squeeze hard into the frame to get the caulk into the joint.

Draw the caulk tube tip along the length of the joint while carefully squeezing the caulk gun handle, working at a steady and constant pace.

6. Shave Off Any Excess Beads

Wet a small plastic spoon, ice cream stick, cloth, or your finger with rubbing alcohol (for silicone caulk) or water (for latex caulk). The alcohol or water will act as a lubricant and thinning agent as you smooth the joint. Smooth the caulk joint with gentle pressure, working your way from one end to the other. 

7. Reinstall Dismantled Trims If Any

If you have disassembled or dismantled any trims or other additional parts, you can reassemble and reinstall them.

Get Free Window Estimates in 30 Seconds
Connect with trustworthy experts in your area.

Tips for Caulking Exterior Windows

Caulking outdoor window frames is a simple DIY project, but if you’re new to caulking, these tips can come in handy.

  • Don’t caulk over existing caulk. It’s important to remove old caulk before applying a new sealant. Leaving the old exterior caulking can result in a poor seal and window appearance.
  • Use a caulking gun with a thumb release. Thumb release caulking guns allow you to better control the amount of caulk coming out of the gun at any given time.
  • Use both hands. Caulk needs to be applied straight. You should always use two hands, keep your wrists straight, and move your elbows and body to run a bead. Don’t move your hands.

Conclusion

Sealing window frames outside is a must to protect your home and windows. It acts as a barrier against the elements, meaning your home stays comfortable and water is kept out. It’s an easy DIY project that should only take you a few minutes, but skipping it can result in some high energy bills and damage to your home and windows.

Frequently Asked Questions

How long does exterior window caulking last?

When the right sealant is used and it’s applied correctly, exterior caulking on windows should last between 10 to 20 years.


What should you look for in exterior window caulk?

The sealant you choose for your exterior windows can depend on your location, UV exposure, weather, and home construction materials. Homeowners should generally look for caulk that is water resistant, UV-resistant, and durable, while also being adhesive to the construction. Additionally, you may need caulking that is paintable.


Can you use caulk for gaps in poorly trimmed windows?

No, you shouldn’t use caulk on poorly trimmed windows. Caulk is best used for seams that are 1/4″ wide or smaller. If your window trim is poor or the caulk is used in wider gaps, it could result in a poor appearance and seal. A backer rod is recommended in these situations.


Article Update Log
5/19/2024
Reviewed for accuracy, cost data, industry best practices, and expert advice by Hilary Cairns.
Editorial Contributors
avatar for Hilary Cairns

Hilary Cairns

Hilary Cairns is a writer with 12 years of professional writing experience. She has covered a diverse set of topics such as custom home building, plumbing, HVAC, energy efficiency, and others. A graduate of SUNY New Paltz with a bachelor's degree in English and a concentration in Creative Writing, she discovered her passion for helping businesses and organizations deliver impactful content that changed lives. Originally from New York, Hilary now calls Florida home (along with 2 cats). When not immersed in her writing work, she enjoys playing video games, reading Stephen King, and researching her (and her friends') genealogy.

Learn More