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Caulk Sealant Application

How to Insulate Windows for Winter & Summer

Person applying weatherstrip to window frame

During the winter and summer, our homes may be too cold or too hot. Instead of spending large amounts on insulation for walls, ceiling, or flooring, or having your energy bill skyrocket, it may secretly be the windows that are the true problem.

Installing insulation is simple and inexpensive. This easy and painless solution can make a huge difference. Below you can learn all about the different types of insulations and how to install them yourself.

How to Tell If You Need to Insulate Your Windows

Person Hands Applying Silicone Sealant With Caulking Gun

Knowing if your windows need insulation is vital for keeping your preferred room temperature from being tampered with by the weather. Start by inspecting your windows. Checking for cracks or gaps in your windows and frames is a good indicator of whether you need to insulate them or not. You can also wait until summer or winter rolls around and try to feel for any drafts coming in from your windows.

It is also important to note if you have preexisting insulation, like caulking or weather strips, after a year or so, they can become ineffective, so you may have to remove them and reapply.

When to Insulate Windows

When deciding on a good time to start insulating your windows, it’s better safe than sorry to begin before the heat or cold sets in from the season. You can also wait closer to the upcoming season and feel for drafts coming through your windows.

Types of Window Insulation

When deciding on how to insulate your windows best, there are many options. The best and most inexpensive way is to either use caulk, weather strips, or insulation film. 

Below describes the different types of insulation for each category, what tools you’ll need, and how to properly apply them.

1. Caulk

Close-up Of Person Hand Applying Silicone Sealant With Silicone Gun On Window

The first type of window insulation is caulking. Caulking is generally inexpensive and fairly easy to use. There are several different types of caulk

Acrylic Latex Caulk
A water-based caulk that is easy to clean up and is meant for the interior of the window. It is mainly used for the window sash, or it can be used around the window in tight spaces. 

Siliconized Caulk
Siliconized caulk is similar to acrylic latex meant for the exterior of your window. The silicone is built with a strong resistance to weather and is to be used on metal and glass surfaces.

2. Weather Strip

Person apply weatherstrip to window frame

Another option for insulating your windows is using weather strips. These strips are applied to the movable parts of the window. Once you put the weather strips on, do not open that window again for the season, or else you will have to reapply it. 

There are three different types of weather strips you can use on your windows:

V Strip

V Strip can be folded into a “V” shape that will open to close gaps. The V Strip has a peel and stick, so it will stay once it’s put on. It can be applied to the sides of the window.


Felt is a cheaper but less durable option for a weatherstrip. This strip can be used on a window sash, once you have the correct length for where you need to put it, you will then have to staple or nail the strip in place.

Foam Tape

Sold in various sizes, foam tape is great for any sized cracks. Equipped with a stick back it goes on easily. Like the felt, this tape is meant to be applied on window sashes.

3. Insulation Film

Window insulation film is a great way to keep out the harsh temperatures. By applying an insulation film on the outside of your window, it can cover up a lot of the gaps and reduce drafts. Additionally, insulation film offers protection from UV rays and still lets you enjoy natural light.

Tools and Materials Needed

CaulkWeather StripInsulation Film
Putty Knife Measuring TapeMeasuring Tape
Utility KnifeWeather StripsScissors
CaulkRagExtension Cord
Caulk GunWindow Cleaning Accessories
Long Nail or Coat HangerInsulation Film
Smooth UtensilSticky Tape

Caulk Window Insulation Instructions

Step 1: Clean the designated areas

Once you have addressed the areas where you will need to apply caulk, it’s essential to have the designated areas ready and cleaned up. You can use your putty knife to chip away any of the old caulk or other protruding pieces. 

Step 2: Preparing

Once you have the areas properly ready, you will now need to puncture the seal inside the caulk. You can use your long nail or coat hanger and insert it into the caulk until you feel it puncture the seal; this will allow the caulk to flow. Then you can now place the caulk in the caulk gun. 

If needed, using your utility knife, you can cut the top of the caulk to adjust it to fit the sizes of the cracks you are trying to cover.

Step 3: Applying the caulk

Now that the caulk gun is ready, you can start at the areas where it is needed and slowly apply the caulk. Make sure to use light pressure on the trigger when applying. Once you have covered up all the cracks, you can use a smooth utensil or finger to create a smooth surface on the caulk. Slowly the caulk will begin to harden and create an airtight seal for the window and cracks.

After finishing the task, make sure to clean the tip of the caulk gun so it doesn’t harden.

Weather Strip Window Insulation Instructions

Step 1: Clean the designated areas

Before applying weather strips, it’s a good idea to clean the areas where you plan to put them. Using a damp rag, brush the appropriate areas and then wait for it to all dry.

Step 2: Measuring & cutting

Once the areas have dried, using your measuring tape, find the dimensions of the specific areas so you will know where to cut your weather strips.

Step 3: Applying the weather strips

Lastly, you can now apply the weather strips to the cracks or window sashes you want to put them on.

Window Insulation Film Instructions

Person using hairdryer on insulation film

Step 1: Clean the designated areas

Use your window cleaning products and begin to clean up the window if you’d like, but primarily make sure to clean down the window frames. 

Step 2: Measuring and applying the film

Once you have cleaned the windows and window frames, you can start measuring. When cutting the film, try to leave some space, about 10cm, on all sides just in case. Now you will need to grab your sticky tape and place it along with the window frame. After that’s complete, place insulation film on the sticky tape.

Step 3: Tidying up

Now that your insulation film has been put on, either using a smooth utensil or even a finger, apply force to all the edges to make sure the film stays on. After making sure the insulation film is firmly on, grab your hairdryer and extension cord depending on the nearest outlet, and check for any ripples in the film. Gently blow the hairdryer to those areas to give it a clean look. Make sure not to overdry the film; otherwise, it may come off from the sticky tape.

Lastly, once everything looks good, you can cut the extra film hanging off the edges, and then you’re ready to go.

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