Dragon Double Flap Pet Door for Sash Windows
- Double Flap Design: Improved sealing and insulation for sash windows, perfect for winter climates
- Sturdy Aluminum Frame: Available in black or white, with UV-resistant additives for lasting durability
- Adjustable Width: Accommodates windows 22" - 43" wide, suitable for various window sizes and types
- Locking Cover Included: Added security with a top-loading locking cover to restrict pet access when needed
- Effortless Installation: Simple, spring-loaded mechanism for quick and easy installation without cutting into your door or wall
- Custom orders are made to your specifications and are non-returnable
- Approximately one month to build your custom pet door; reach out to our customer service team for expedited shipping options
-
Panels less than 22" will have no glass

Product Details
The Dragon Double Flap Pet Door for Sash Windows offers a flexible, translucent flap that combines with a double flap design, making it suitable for dogs and cats of all sizes while ensuring optimal weather resistance.
The Dragon Pet Door is designed for sash windows and is adjustable to fit windows from 22" to 43" wide. The easy installation process is a breeze, thanks to the spring-loaded mechanism that securely fits into your window track. The aluminum framing, available in black or white, is not only durable but also features UV-resistant additives to prevent warping and cracking.
The double flap system not only maximizes energy efficiency but also provides an extra layer of protection against cold weather. This pet door is perfect for renters or those who prefer a non-invasive installation, as it doesn't require any holes to be cut into your door or wall. Your pets will love the freedom to come and go as they please.
Safety and security are paramount, which is why the Dragon Sash Window Pet Door includes a top-loading locking cover that can be used to restrict pet access and deter intruders. The locking cover slides into the interior frame for added peace of mind.
Don't need two flaps? For mild climates, check out the Dragon Single Flap Pet Door For Sash Windows.
Features:
- Translucent, Flexible Flap: Allows easy access for pets of all sizes and ensures optimal weather resistance
- Energy-Efficient Double Flap System: Maximizes insulation and protection against cold weather
- Non-Invasive Installation: Ideal for renters or vacation homes, with no need to cut into doors or walls
- Aluminum Frame: Designed to fit window tracks at least 1" thick for a secure and stable fit
- Top-Loading Locking Cover: Provides added security and restricts pet access when necessary
Benefits:
- Window doggie door allows pets the independence to come and go as they please
- Simple, quick installation, easily removable; ideal for renters or vacation homes
- Flexible flap is safe and comfortable for dogs and cats to use
Size Chart
- Small 5 3/8"w x 7 1/16"h
- Medium7 1/16"w x 13 1/16"h
- Large9 3/8"w x 16 9/16"h
Flap Dimensions:
5 3/8"w x 7 1/16"h
The entry way your dog goes through.

Height To Raise Window
15 7/16"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
7 1/16"w x 13 1/16”h
The entry way your dog goes through.

Height To Raise Window
21 5/8"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
9 3/8"w x 16 9/16"h
The entry way your dog goes through.

Height To Raise Window
25 5/16"
How high you must raise your window in order to fit the panel into the track.Flap Size | Flap Dimensions | Step Over | Height to Raise Window | Recommended Pet Height* |
---|---|---|---|---|
Small | 5 3/8"w x 7 1/16"h | 3" | 15 7/16" | 9" - 12" |
Medium | 7 1/16"w x 13 1/16"h | 3" | 21 5/8" | 11" - 16" |
Large | 9 3/8"w x 16 9/16"h | 3" | 25 5/16" | 11" - 22" |
*measured from the ground to the tallest point of their back.
IMPORTANT SIZING INFORMATION
The Dragon Pet Door’s two-piece flap is designed to tear away for your pet’s safety. If you pet door is not the right size for your pet, they may break off flap during normal use. Follow these sizing tips to help ensure that you are buying the right Dragon Pet Door size:
- Check the Flap Height: You must measure your dog before purchasing a pet door. A large dog may not fit in a “large” pet door. The tallest point of your dog’s back should be at least 1” beneath the top of the flap.
- Check the Step-Over: Your pet should be able to over the bottom of the flap comfortably. If the distance from the floor to the bottom of the pet door (called the stepover) is too high, your dog’s paw may catch in the pet door’s U-gasket. It’s better to have a taller pet door that is lower to the ground than a smaller pet door that is too high up.
- Check Your Entry/Exit Level: The inside of your home may be higher than the ground outside. This means that your door may have different step-over heights depending on whether you are indoors or outdoors. Try to use the lower level when picking your step over height. You can also even of the different levels with a ramp or platform.
- Reinforce Your Flap: Every Dragon Pet Door comes with instructions for how to reinforce the screws keeping your flap in place. If you are worried in any way that your pet may rip off the flap, we recommend preemptively reinforcing your flap. Note that doing so will negate the teat-away safety feature.
If you have any questions about which size pet door your pet needs, please contact our team of pet door experts for guidance and recommendations.
Find The Best Pet Door Size For My Pet

A
Pet Height: inches
B
Pet Width: inches
Installation Instructions

Parts
- 1 Sash Window Insert with a Pre-Installed Single Flap Dragon Pet Door
- 1 Foam Weather Strip
- 1 Locking Cover
Tools
- Flathead Screwdriver
Please read instructions & notes thoroughly before installation.
Step 1 Release Spring Mechanism

- Loosen the width adjustment locks at the end of the sash with a screwdriver. This allows the spring mechanism to move freely from side to side.
Step 2 Test Fit in Window Track

- Before applying weatherstripping, insert the sash into the window track to test he fit.
- Push into the spring mechanism and swing the opposite end into the opposite window track. Gently release then tighten the width adjustment locks.
Step 3 Apply Weather-Stripping

- Once you have confirmed the sash fits, loosen the width adjustment locks and remove it from the frame.
- Apply the foam weatherstripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres.
- Use scissors to trim the strip to fit the length of your sash. Apply to both the top and the bottom.
Step 4 Lock Into Track

- Place the sash back into the window, then tighten the width adjustment locks to lock it in place.
LOCKING YOUR WINDOW
For a temporary lock, place a removable wooden dowel or charley bar in either track above the window, shown here. For a permanent lock, install a screw in the track immediately above the window on both sides. You will no longer be able to raise the window.
FREQUENTLY ASKED QUESTIONS
What if my window is slightly too narrow?
The sash can be trimmed up to 3/4” in cases where it is a bit too wide to fit into the track. Remove the spring-loaded adjustment pieces using a #2 Phillips head screwdriver. Using a clamp and a flat surface, cut off the flanges using a jigsaw with a metal cutting blade. You can also use a hacksaw, though it is more labor intensive and you may end up with a less clean cut. The dark area marks where you can trim:
What if my window doesn’t open enough?
Some windows will have stops that prevent them from fully raising up. In some cases, these can be removed allowing it to go up far enough to get the sash in place. You want to be careful when removing them, as it could damage the window or void the window’s warranty.
What if the track is too narrow for the pet door?
The spring adjustment pieces are slightly wider than the rest of the pet door, which may prevent it from fitting in the track. There are several potential solutions. One, you can trim one of the flanges off the spring-loaded adjustment piece, turning the "U" shape at the end into an “L". Alternatively, you can remove just one of the adjustment pieces with a Phillips head screwdriver and add shims for a snug fit.
You could also use a small piece of board in the channel of the adjustment piece, shown here. This board can be thinner and extend into the track giving the tension you need to hold it in place. Last option would be to install the sash using brackets to screw it into the track. Brackets would need to be made or purchased from your local hardware store.
What can I do if the track is wider than the pet door?
If the track is too wide to support the sash upright, you can use foam weather stripping or shims inserted into the track on the sides and/or bottom to fill up any of the gaps causing it to wobble. For a more permanent option, you can toe nail the sash into the framing with screws.
Switch the Side of the Flap
You can switch which side of the sash panel the pet door flap is on to best fit your home.
Step 1
- Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.
Step 2
- Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.
Step 3
- Replace the end spacer and screws.
FAQ
Is the Dragon sash window pet door easy to install?Yes, the Dragon sash window dog door is easy to install in a matter of minutes. The spring-loaded design allows you to easily insert the panel in your sash window track. |
How do you lock a sash window doggy door?To lock your sash window with a dog door window insert, a good option is to install a wooden dowel in the track above the window. For a permanent lock, install a screw in the track immediately above the window on both sides. |
Do you sell any replacement flaps?Yes, we carry replacement flaps for our doors. |
Can my large and small dog share this pet door?Yes, but before you purchase, make sure to follow sizing guidelines and measure your pet before purchasing. Make sure the size of the door is based off your tallest pet, but installed low enough for your smallest pet. |
How do I know what size will be best for my dog?You want to make sure that the top of your new pet door clears your dog's back by 1-2 inches minimum. Make sure the step-over is less than 1/3 of your dog's height in order to ensure that the pet door is as comfortable for your dog to use as possible. Lastly you want the width of the door to be wide enough to allow your dog and cat to go through without touching the sides. Here's a guide on how to measure your pet with tips on how to determine the correct size. |
I want to get the large pet door for my dog, but I am worried that a burglar could fit through it.Every Dragon Pet Door comes with a locking cover. This cover can be used to keep your dog in as well as keep intruders from entering your home. |
Is there a difference between the single flap and the double flap?The double flap option provides increased insulation against the cold. Both options have magnets on the flap to keep the door sealed in wind. |
What do I do if my window opens left to right?If you have a horizontal-opening window, then you should check out the Dragon Single Flap Pet Door For Windows. |
Warranty
Dragon Pet Doors One Year Warranty
Dragon Pet Doors have a one-year warranty for normal wear and tear and manufacturing defects.
Customer Reviews

Size Chart
- Small 5 3/8"w x 7 1/16"h
- Medium7 1/16"w x 13 1/16"h
- Large9 3/8"w x 16 9/16"h
Flap Dimensions:
5 3/8"w x 7 1/16"h
The entry way your dog goes through.

Height To Raise Window
15 7/16"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
7 1/16"w x 13 1/16”h
The entry way your dog goes through.

Height To Raise Window
21 5/8"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
9 3/8"w x 16 9/16"h
The entry way your dog goes through.

Height To Raise Window
25 5/16"
How high you must raise your window in order to fit the panel into the track.Flap Size | Flap Dimensions | Step Over | Height to Raise Window | Recommended Pet Height* |
---|---|---|---|---|
Small | 5 3/8"w x 7 1/16"h | 3" | 15 7/16" | 9" - 12" |
Medium | 7 1/16"w x 13 1/16"h | 3" | 21 5/8" | 11" - 16" |
Large | 9 3/8"w x 16 9/16"h | 3" | 25 5/16" | 11" - 22" |
*measured from the ground to the tallest point of their back.
IMPORTANT SIZING INFORMATION
The Dragon Pet Door’s two-piece flap is designed to tear away for your pet’s safety. If you pet door is not the right size for your pet, they may break off flap during normal use. Follow these sizing tips to help ensure that you are buying the right Dragon Pet Door size:
- Check the Flap Height: You must measure your dog before purchasing a pet door. A large dog may not fit in a “large” pet door. The tallest point of your dog’s back should be at least 1” beneath the top of the flap.
- Check the Step-Over: Your pet should be able to over the bottom of the flap comfortably. If the distance from the floor to the bottom of the pet door (called the stepover) is too high, your dog’s paw may catch in the pet door’s U-gasket. It’s better to have a taller pet door that is lower to the ground than a smaller pet door that is too high up.
- Check Your Entry/Exit Level: The inside of your home may be higher than the ground outside. This means that your door may have different step-over heights depending on whether you are indoors or outdoors. Try to use the lower level when picking your step over height. You can also even of the different levels with a ramp or platform.
- Reinforce Your Flap: Every Dragon Pet Door comes with instructions for how to reinforce the screws keeping your flap in place. If you are worried in any way that your pet may rip off the flap, we recommend preemptively reinforcing your flap. Note that doing so will negate the teat-away safety feature.
If you have any questions about which size pet door your pet needs, please contact our team of pet door experts for guidance and recommendations.
Find The Best Pet Door Size For My Pet

A
Pet Height: inches
B
Pet Width: inches

Parts
- 1 Sash Window Insert with a Pre-Installed Single Flap Dragon Pet Door
- 1 Foam Weather Strip
- 1 Locking Cover
Tools
- Flathead Screwdriver
Please read instructions & notes thoroughly before installation.
Step 1 Release Spring Mechanism

- Loosen the width adjustment locks at the end of the sash with a screwdriver. This allows the spring mechanism to move freely from side to side.
Step 2 Test Fit in Window Track

- Before applying weatherstripping, insert the sash into the window track to test he fit.
- Push into the spring mechanism and swing the opposite end into the opposite window track. Gently release then tighten the width adjustment locks.
Step 3 Apply Weather-Stripping

- Once you have confirmed the sash fits, loosen the width adjustment locks and remove it from the frame.
- Apply the foam weatherstripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres.
- Use scissors to trim the strip to fit the length of your sash. Apply to both the top and the bottom.
Step 4 Lock Into Track

- Place the sash back into the window, then tighten the width adjustment locks to lock it in place.
LOCKING YOUR WINDOW
For a temporary lock, place a removable wooden dowel or charley bar in either track above the window, shown here. For a permanent lock, install a screw in the track immediately above the window on both sides. You will no longer be able to raise the window.
FREQUENTLY ASKED QUESTIONS
What if my window is slightly too narrow?
The sash can be trimmed up to 3/4” in cases where it is a bit too wide to fit into the track. Remove the spring-loaded adjustment pieces using a #2 Phillips head screwdriver. Using a clamp and a flat surface, cut off the flanges using a jigsaw with a metal cutting blade. You can also use a hacksaw, though it is more labor intensive and you may end up with a less clean cut. The dark area marks where you can trim:
What if my window doesn’t open enough?
Some windows will have stops that prevent them from fully raising up. In some cases, these can be removed allowing it to go up far enough to get the sash in place. You want to be careful when removing them, as it could damage the window or void the window’s warranty.
What if the track is too narrow for the pet door?
The spring adjustment pieces are slightly wider than the rest of the pet door, which may prevent it from fitting in the track. There are several potential solutions. One, you can trim one of the flanges off the spring-loaded adjustment piece, turning the "U" shape at the end into an “L". Alternatively, you can remove just one of the adjustment pieces with a Phillips head screwdriver and add shims for a snug fit.
You could also use a small piece of board in the channel of the adjustment piece, shown here. This board can be thinner and extend into the track giving the tension you need to hold it in place. Last option would be to install the sash using brackets to screw it into the track. Brackets would need to be made or purchased from your local hardware store.
What can I do if the track is wider than the pet door?
If the track is too wide to support the sash upright, you can use foam weather stripping or shims inserted into the track on the sides and/or bottom to fill up any of the gaps causing it to wobble. For a more permanent option, you can toe nail the sash into the framing with screws.
Switch the Side of the Flap
You can switch which side of the sash panel the pet door flap is on to best fit your home.
Step 1
- Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.
Step 2
- Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.
Step 3
- Replace the end spacer and screws.
FAQ
Is the Dragon sash window pet door easy to install?Yes, the Dragon sash window dog door is easy to install in a matter of minutes. The spring-loaded design allows you to easily insert the panel in your sash window track. |
How do you lock a sash window doggy door?To lock your sash window with a dog door window insert, a good option is to install a wooden dowel in the track above the window. For a permanent lock, install a screw in the track immediately above the window on both sides. |
Do you sell any replacement flaps?Yes, we carry replacement flaps for our doors. |
Can my large and small dog share this pet door?Yes, but before you purchase, make sure to follow sizing guidelines and measure your pet before purchasing. Make sure the size of the door is based off your tallest pet, but installed low enough for your smallest pet. |
How do I know what size will be best for my dog?You want to make sure that the top of your new pet door clears your dog's back by 1-2 inches minimum. Make sure the step-over is less than 1/3 of your dog's height in order to ensure that the pet door is as comfortable for your dog to use as possible. Lastly you want the width of the door to be wide enough to allow your dog and cat to go through without touching the sides. Here's a guide on how to measure your pet with tips on how to determine the correct size. |
I want to get the large pet door for my dog, but I am worried that a burglar could fit through it.Every Dragon Pet Door comes with a locking cover. This cover can be used to keep your dog in as well as keep intruders from entering your home. |
Is there a difference between the single flap and the double flap?The double flap option provides increased insulation against the cold. Both options have magnets on the flap to keep the door sealed in wind. |
What do I do if my window opens left to right?If you have a horizontal-opening window, then you should check out the Dragon Single Flap Pet Door For Windows. |
Warranty
Dragon Pet Doors One Year Warranty
Dragon Pet Doors have a one-year warranty for normal wear and tear and manufacturing defects.