Tools and Materials

Tools

Materials

Note

Product costs, availability and item numbers may vary online or by market.

Measuring Your Pet

A sizing chart and diagram showing how to measure a pet for a new pet door.

Before purchasing a new dog door or cat door, consider the size. The width of the pet door should be 2 inches wider than the measurement between your pet’s shoulders (see pictured: B). The height of the pet door should be 2 inches taller than the measurement between the top of your pet’s shoulders and the bottom of its chest (see pictured: C).

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Caution

Check your local building codes and insurance policy. Fire-rated exterior doors are required in some areas. Installing a pet door may be in violation.

Using a Template to Install a Dog Door

Most pet doors include a template for placement. Cut out the template as instructed. If your pet door doesn’t include a template, use the plastic slide as a template. Place the template in the desired location on the door, at least 3 inches above the bottom edge of the door. Tape the template in place. Then follow the instructions below.

Good to Know

Some exterior storm doors are sold with pet doors already installed, so you can save some time and energy, especially if your exterior doors are due for an update.

How to Install a Pet Door

Here are the steps for installing a pet door yourself.

Instructions

A person using a tape measure and pencil to mark the bottom edge of the pet door.

Most pet doors include a template for cutting the hole. The height of your pet’s shoulders will help you determine the appropriate placement for the hole to give your pet comfortable access. Position the template in the desired location on the door. Make sure the template is level and that the lowest cutting mark is at least 3 inches above the bottom edge of the door. Tape the template in place, and then cut out the appropriate-size template for your installation. Tape the template to the door.

How to Install a Cat Door or Cat Flap

A white sash window cat door with side panels extended and the flap partially open.

Installing a standard cat door in an exterior door is similar to the steps above. One type of pet door that can work particularly well for cats is a sash window cat door or cat flap. This type of cat door has a flap like a standard pet door and works in most windows with a lower sash that opens vertically. Installing a sash window pet door is a simple project, and it’s not a permanent installation, so it’s easy to take out if you move, allowing the window to function normally again. We’ve provided general steps for installing a cat door in a window, but always follow the instructions for your model.

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Tip

Be sure to measure your window’s width and make note of how high the lower sash opens to ensure the model you choose will fit.

Instructions

Raise the bottom window sash and place the cat door in the window opening. The door assembly will have a set of knobs that allow you to release and secure expansion panels to fit a range of window widths. In some windows, the bottom set of knobs may catch on the windowsill or stool and prevent installation. You can remove the lower set of knobs to fit the door properly.

Remove the screws that secure the expansion panels to the internal spring-loaded rods and then remove the panel from the rods. Push and hold the lower rod just inside the door assembly. This will allow you to unscrew and remove the lower knob. Release the rod and reinstall the expansion panel. If you have two expansion panels, repeat the process for the other side. You should now be able to set the door in the bottom of the window frame. Keep the knobs handy, as you may need them if you reinstall the door in a different window.

Adjust the door to the width of the window.

If the door only has an adjustable expansion panel on one end, set the fixed end of the door against one window frame. Loosen the adjustment knobs to allow the sliding expansion panel to extend to the other side of the window frame.
If your door has two adjustable panels, place the door in the middle of the window opening and then loosen both panels so they extend to both sides of the window frame.

Once you have a good fit and the door is aligned properly, tighten the adjustment knobs to lock the panels to the window frame and secure the door in place.

Tip

If the side panels don’t fit into the window track, you may be able to install the assembly against the window track and secure it in place with corner braces and screws.

To finish the installation, you’ll lower the window sash onto the cat door, but first you need to apply a seal to ensure there will be no gaps between the cat door and the sash. Measure and cut the included seal to length and affix it to the top of the door, making sure it aligns with the sash. Lower the sash in place on top of the seal.

Now that the sash is partially open to accommodate the pet door, there will be a gap between the top and bottom sashes that can allow air to move into and out of your home. The door kit should include a seal for this gap as well. Measure and cut the seal to length. You may need to use two pieces to accommodate the window lock. With the sash down, attach the seal to the top edge, making sure it comes into contact with the glass and closes the gap.

Tip

If the side panels don’t fit into the window track, you may be able to install the assembly against the window track and secure it in place with corner braces and screws.

Since the sash is partially open, the window lock will no longer function. Check your door manual for options for securing the top sash so it can’t be opened.

Some kits come with window stops you cut to fit in the window track above the sash, immobilizing it. If your kit didn’t include these stops, you can cut a couple from paint stirring sticks. You may want to use a few spots of nonmarring adhesive to keep the stops in place.
Depending on the window, you may be able to install wood screws in the window tracks just above the sash to keep it from opening.
For wood windows, you may be able to fasten the upper and lower sashes together with corner braces and screws.
A pin lock that runs through holes in both sashes can immobilize the sash on some windows.

Caution

If you’re installing the door in a rental home, check with your rental agency before making any changes to the window.

Removing the Cat Door

If you ever need to remove the cat door, it’s as simple as the installation. First, uninstall any locking device for the top sash so it can move freely. Remove the seal from the top of the sash. Raise the sash and lock the extension panels on the cat door back in their original position. You should be able to lift the door out of the window. If necessary, reinstall the bottom adjustment knobs.

Teaching Your Pet

A man holding a treat in front of a newly installed pet door, training a small dog to use it.

With a little training, your pet can learn to use the new door. Some people like to leave the flap off for a day or two — this allows your pet to move through easily. It also helps to call your pet through the hole from outside. When your pet goes through the door, offer lavish praise.

Another option is to offer treats or food each time your pet goes through the door. Pet experts recommend that you repeat this reward three times in a row to firmly lock the behavior in place. If you have a younger animal, it may take longer to teach the new practice. Be patient — some animals take longer than others. Once your pet does learn, it'll love the newfound freedom.

Install a Pet Door

Tools and Materials

Tools

Materials

Measuring Your Pet

Using a Template to Install a Dog Door

How to Install a Pet Door

Instructions

How to Install a Cat Door or Cat Flap

Instructions

Removing the Cat Door

Teaching Your Pet

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