Thermo Sash 3e Pet Doors for Sash Windows


  • Consumer favorite for window pet doors
  • Maintains insulation with dual pane, LoE glass in sturdy aluminum framing
  • Installation is a breeze with no tools required, perfect for renters and vacation homes
  • Built-to-last with 15 year warranty, made in the USA
  • Free shipping within the U.S.

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Stock No: 07PPC

Availability: In stock

Price From: $419
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Price From: $419
Thermo Sash 3e Pet Doors for Sash Windows
Thermo Sash IIIe Showing "Endura" Flap large sized dog door

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  • Consumer favorite for window pet doors
  • Maintains insulation with dual pane, LoE glass in sturdy aluminum framing
  • Installation is a breeze with no tools required, perfect for renters and vacation homes
  • Built-to-last with 15 year warranty, made in the USA
  • Free shipping within the U.S.
Flap SizeFlap DimensionFrame HeightHeight to Raise WindowStock No 
Small6" x 11"18"19"07PPC06 
Medium8" x 15""22"23"07PPC08 
Large10" x 19"26"27"07PPC10 
Extra Large12" x 23"30"31"07PPC12 

Don't know which flap size to get? Here is a measurement guide to help you out

Adjustment Ranges

  • 21 3/4" - 25" Custom Order (not available for Extra Large)
  • 24 3/4" - 28"
  • 27 3/4" - 31"
  • 30 3/4" - 34"
  • 33 3/4" - 37"
  • 36 3/4" - 40"
  • 39 3/4" - 43"

Pet door has 1" framing,  measure your track width to make sure that your window will accommodate the sash.

Final Sales   Adjustment Range 21 3/4" - 25" are final sales and cannot be returned. All Extra Large sizes are also custom and non-returnable. Please allow 3-4 weeks for XL Flap models to be built and shipped. 

Thermo Sash 3e Pet Door for Windows

You will not find better insulation and durability than with the Thermo Sash 3e with Endura Flap. The spring-loaded design fits windows of practically any width, and is perfect for a temporary no tools or even year round semi-permanent installation. This is by far the premier choice for window pet doors in the most extreme conditions, and we prove it by backing it with a 15 year warranty!

Features of our Thermo Sash 3e

  • The Endura Flap featured with this door is one of the best engineered high performance pet doors ever made. Magnets on the bottom and up and down the length of both sides give it a superior seal, while allowing you to adjust them for training purposes.
  • Dual pane LoE insulated glass pairs perfectly with the newer energy efficient windows and doors used in new construction and renovated homes.
  • Four different flap choices have a high aspect ratio, meaning they are taller and narrower to better fit more pets.
  • With a spring loaded adjustment panel it can be installed and removed in seconds without the use of any tools.
  • It has adjustment ranges to fit window widths from 22’ - 43”, and if that doesn’t include yours we can even make it custom!
  • We include a draft stopper and weather stripping for extra protection from the elements.
  • The sturdy aluminum framing is available in White, Satin, or Bronze.
  • It is designed, engineered and manufactured in the USA. Check out our detailed Efficiency Study and see what makes us the best!

Perfect Time for a Thermo Sash 3e

  • Hands down the best sash window door on the market for severe situations, whether it’s wind, rain, snow, or heat.
  • The adjustable magnet strengths makes training your pets much easier, so if you have smaller or slightly timid dogs and cats no need to worry.
  • Temporary install makes it great for renters and vacation homes.
  • The Thermo Sash is a pet door you can fully depend on, with the flap lasting years even with constant use.
  • The flap sizes of this doggy or cat door can accommodate multiple pets, from small to large and any sharing in between.

Customer Reviews

Set Direction
  • Great Dog Door review by Debra
    5 5 Great Dog Door

    I purchased the XL Thermo Sash 3e. It was easy to install and fits snugly in the window. I have six dogs - a 165 lb St. Bernard/Newfoundland mix, a Golden Doodle, a Bernese Mountain Dog, a Catahoula Leopard Dog, a St. Bernard/Great Pyrenees mix and a Pug. All of them can easily open the flap and get through the opening. At times the pack can get pretty crazy and the door stays secure with all of them trying to get in and out at the same time. I'm very satisfied and would heartily recommend this door.

    (Posted on 1/3/2019)

  • Had to break my window to install review by Nicole
    5 2 Had to break my window to install

    The construction of the pet door is very good, very solid and I do believe in theory it would have worked to keep my basement warm all year. My issue with the pet door is that it was very difficult to install. I had anticipated an easy installation based on the description and reviews. We had to break our window in order for it to open tall enough to get the pet door window in. Once we got the window opened enough to place the pet door the edges of the door were too wide to truly fit in the window frame. We then had the option to continue to break our window or just put more insulation around the edges and we chose to put insulation around the edges. For an expensive pet door I am disappointed in the installation and fit. I think it will work and I need a pet door so I am keeping it but I am disappointed with the fit and the price. I also feel as though I really can't try a different pet door at this point because we broke our window trying to install this one.

    (Posted on 12/5/2018)

  • Nice quality and great company review by Linda
    5 5 Nice quality and great company

    The people at were friendly and very willing to help us choose the right door. We have a unique situation in which we could not install a dog door in our door and they helped us pick one for a window. The window dog door is solid construction and was pretty easy to install. It came with insulation and a protective solution to protect the door flap from sun damage. The door works great! Would definitely buy from them again.

    (Posted on 8/14/2018)

  • I searched diligenly for a pet door to fit in an existing sash window. I followed the measuring advice for dog and window...and I am very satisfied with the product. Installation was fairly simple, and I found the additionaly added weather stripping to review by Todd
    5 5 I searched diligenly for a pet door to fit in an existing sash window. I followed the measuring advice for dog and window...and I am very satisfied with the product. Installation was fairly simple, and I found the additionaly added weather stripping to

    See above.

    (Posted on 8/2/2018)

  • Met all expectations! review by Terri
    5 5 Met all expectations!

    I was a little skeptical about purchasing this due to the high price but it is definitely worth it. The panel fits perfectly in my window and the installation took less than 30 minutes. The medium size was perfect for my 30 lb dog and it wasn't too hard to train with! When I asked for tips on training, the customer service rep gave me a link to the video on how to adjust the magnet strength. Highly recommend!

    (Posted on 12/27/2017)

  • looks good and fits okay review by Michele
    5 4 looks good and fits okay

    It's such a well done product, everything is perfect. The fit is a little loose because with a bigger track it could wiggle. Put down some weather stripping/strong material and it's nice and secure!
    Might be more insulating than the actual window

    (Posted on 12/5/2017)

  • 1st Class and some!! review by Kelly
    5 5 1st Class and some!!

    Great asset for any pet lover who wants to give their pets more independence to go in or out on their own. Quality even greater than hoped for.. 100% satisfied...

    (Posted on 11/25/2017)

  • Amazing Pet Door! review by Diane
    5 5 Amazing Pet Door!

    My dog loves her pet door, I love that it is high quality, nice looking, easily installed and fairly insulated from the Texas heat and as a Realtor, I love that it is not permanant and won't leave any evidence of ever being in the window.

    (Posted on 7/26/2017)

  • Expensive but fantastic review by Joseph
    5 5 Expensive but fantastic

    I was skeptical, but I think it's definitely worth having a good product.

    (Posted on 3/15/2017)

  • Perfect Solution! review by anneengland
    5 5 Perfect Solution!

    We've had this pet door for almost 2 years now and it is wonderful! We have a telescoping ramp on the outside and a smaller plastic ramp inside for our older dog. Texas winds, hail & rain do not affect it - stays tightly closed, yet easy for our dog to go in or out. Less expensive than a new back door, as houses here all have lots of windows floor to ceiling and glass pane back doors. A great investment, and if we ever move, it is removable and reusable!

    (Posted on 9/10/2016)

  • Superb review by Krisa
    5 5 Superb

    Quality exceeded my expectations. Highly recommend.

    (Posted on 5/8/2016)

  • Cats are happy. review by Rally
    5 5 Cats are happy.

    All but one cat has gotten use to the new flap. Since it was for cats, they put in only one magnet in. One side doesn't always close tight and I have to help it. I'm thinking of asking for 1 more magnet. Overall, the door is very sturdy and helps keep the cold out. I would recommend it to anyone. It is pricey, but so far, I feel it's worth it.

    (Posted on 2/15/2016)

  • excellent pet door review by ally
    5 5 excellent pet door

    this pet door is absolutely worth it. it is definitely worth the money. it is easy to install and my cats learned how to use it without great difficulty

    (Posted on 1/19/2016)

  • It's great! review by Lou
    5 5 It's great!

    My cat loves it! She was a feral cat and hates being stuck inside so this gives her easy access to the outside. We are now into single digit temperatures and I have not had any problems with cold air seeping in or around the cat door. It is a bit noisy when she goes in and out but I actually find that reassuring -- let's me keep track of her comings and goings.

    (Posted on 1/8/2016)

  • Nice pet door review by SteveInGb
    5 4 Nice pet door

    This is a nice pet door that works well. The only draw back is that the frame is aluminum and not insulated or thermally broken, which means that if you are in a colder climate and utilize humidifiers, all of the aluminum components will sweat, sometimes a lot, since it will be near the same temperature as the outside air. Think glass of ice water on a hot humid day.

    (Posted on 12/7/2015)

  • Great Pet Door review by Hillcountry
    5 5 Great Pet Door

    Easy installation, dogs started using it with little training and it looks great. Now we don't have to get up and down to let the dogs each.

    (Posted on 5/1/2015)

  • Great Pet Door review by CL
    5 5 Great Pet Door

    My small dogs and two cats had no problem using it. They were used to a pet door we had at our last house. They just know to push with their head a littler harder to get through. It stops a lot of cold and hot air from coming into the house. Now our puppy was scared of it first. We taped it open for a few days and rewarded her with a treat to go in and out. After we closed it, she would wait till the small dog open it and then she would follow. Now she has learn to push it open with her head and not afraid of it now.

    (Posted on 12/17/2014)

  • Great! review by J.C.
    5 5 Great!

    It took about 3 days for the 2 cats to understand they did not have to get us to let them outside but took the puppy a little longer. Once the dog understood there was no stopping him - out/in - out/in. Since the weather has turned a little cool he now goes out only when he has to. Even when we go out the human door he will go out 'his' door to join us. What a great thing to have with 3 (soon to be 4 pets). Very well made and looks good also. Thanks!!!!!!!

    (Posted on 11/16/2014)

  • Easy to install and attractive review by Windsailor
    5 5 Easy to install and attractive

    Excellent design, well worth the price, so easy to install, attractive.

    (Posted on 7/31/2014)

  • Excellent pet door for windows review by Ken
    5 5 Excellent pet door for windows

    I have used another brand product for 20+ years with flaps that allowed air-conditioned air out and cold air in in the summer. Even when I bought new flaps they did not seal very well at all.
    This product was easy to install, looks good in the window, and seals perfectly. The price is well worth it. I would buy it again in a heartbeat.

    (Posted on 7/29/2014)

  • Excellent review by Michael
    5 5 Excellent

    The door works very well and we like the insulation of the double pane. The dog loves it. Seems very sturdy and with the magnetic door the wind can't blow it open. That's about it.

    (Posted on 1/15/2014)

  • Excellent Product review by ktwindow
    5 5 Excellent Product

    We ordered the small size door for our cat. My husband installed the window. He did not appear to have any difficulty but he's an engineer. We did need to go get some extra weatherproofing for our window but we have old sash windows and our gap was too wide for the included weatherproofing strip. Not a big deal as we were able to find what we needed at a hardware store. Our cat was used to an old door flap that did not have magnets and she could open with her paws. It did take her some time to adjust as she has to open it with her face. I did put painters tape around the sides over the magnetized area and taped down the bottom piece for about a month- this made it open much easier. We did move her food dish outside to provide additional incentive for her to use it. After a month, we removed the tape and she uses it like a champ. It seals nicely and does not let in a draft.

    (Posted on 1/7/2014)

  • Replacement Flap is a Challenge review by Brian
    5 4 Replacement Flap is a Challenge

    The product is great, but the challenge to replace the flap is miserable. The directions that come with the replacement flap are only for the "Quick Panel" version, and not the sash window.

    (Posted on 12/21/2013)

  • Cats love it! review by Nenz
    5 5 Cats love it!

    This window is great! The magnet is strong and it took awhile for them to get used to it compared to the soft plastic flap doors. It is now winter in the Northeast and the bedroom where this door is does not leak cold air. I used weather stripping provided along with some extra I bought at the store. You probably don't even need the extra stripping, I just wanted to make sure. I am very pleased with the purchase and would definately recommend it to others. Also, they love the window on the side panel!

    (Posted on 12/19/2013)

  • Attractive, functional, highly recommend review by LOVE IT!
    5 5 Attractive, functional, highly recommend

    After purchasing and returning 4 different pet doors, and cutting a hole in an interior wall to find that a major electric wire was blocking the opening… We finally found the Thermo-Sash Pet Door for windows. It matches our window so perfectly, no one notices it. It took a couple of weeks and treats to train our cat, but no more late night meowing to get out or come in! I had no trouble placing it, and it looks great. FYI, I removed a few magnets to enable our cat to more easily open during training. They are easily reinserted.

    (Posted on 11/26/2013)

  • Good quality, but pricey review by Dave18
    5 4 Good quality, but pricey

    This is a high quality pet door that is well-built and looks like it will last for years. I purchased it fully aware of the fact that it might be too thick to fit into my window frame (the channels in my windows are less than 1" wide), but it was the closed thing to what I wanted it, so I took the risk. I was able to make it fit using some wood strips, insulation tape, and a little ingenuity. The dogs love it, but I am still trying to figure out why it costs so much. It would be a much better deal in the $150 t0 $200 range (I bought the smallest size).

    (Posted on 7/29/2013)

  • Good Product in Bad Condition review by Wren
    5 4 Good Product in Bad Condition

    The box arrived with a big tear in the side and one of the heavy knobs for securing the door was badly bent. The box was falling apart and the tape was coming loose like it had dried out.
    The return instructions were rather strict....from what I read..They will not accept a damaged package?? They suggest you repackage in fresh materials. This is a big door with lots of Styrofoam etc. As a result I decided to try and use it damaged. It is working fine and does appear to seal and insulate well.

    ed. note - packages with visible damage should be inspected at once. If there is damage to the contents, we will issue a 'damage call tag' immediately, pick up the damaged item and replace the product at no charge to the customer. This applies to any product, not only those we manufacture.

    (Posted on 6/23/2013)

  • Excellent review by Kathy
    5 5 Excellent

    Very satisfied with all aspects of door. Had been wanting a pet door for some time but didn't have a door or wall in which to install so this window version worked great. Installation was quick & easy.

    (Posted on 4/29/2013)

  • Good for cats review by Amy
    5 5 Good for cats

    Good window, easy to install once we got the sides trimmed down 1/4 inch (you'l need a hack saw), The door works great and seals really well. Training the cat took about 2 weeks but once he got the hang of it things were so much easier. no more having to get up and let him in or out all the time or listen to him cry. The only draw back now is he like to bring his "toys" inside on occasion. Sometimes still breathing :~(

    (Posted on 4/27/2013)

  • Outstanding review by Sambo
    5 5 Outstanding

    Our home has two doors leading to the back patio. Both doors are glass pane doors. The unit we purcchased was a perfect solution as we cid not have to modify or purchase or modify the door. Installation went very smooth and with a bit of coaching our dog to use her new entrance the solution works like a charm. The quality of the pet door is great. Buttercup, our dog, says "Thanks America's Finest Pet Doors".

    (Posted on 3/31/2013)

  • Love This Door! review by Jamie
    5 5 Love This Door!

    We purchased this doggie door for our 3 Labs. It took about a week for all 3 to get the courage to push it open on their own. Took another week to get them to use the doggie door and stop asking me to get up and let them out the back door. But they finally got it. We actually get to sleep in a little on the weekends now. Amazing! The door is really great. The quality couldn't be any better. We just love it and highly recommend it.

    (Posted on 3/21/2013)

  • So happy to have it review by Doggie Door
    5 5 So happy to have it

    The product was easy to install. Took less than 5 minutes. We have two 85 lb dogs, and they are so happy to have it. The cost was 1/4 of what we were going to spend getting doors installed with dog doors in them. What a lifesaver (and moneysaver)!

    (Posted on 3/12/2013)

  • best door ever! review by bco
    5 5 best door ever!

    I have had three of these doors: the first, installed in the wall of my old house; the second in a human door; the third, the Thermo-sash. These are wonderful doors! They keep snow, wind, and uninvited critters out, but are very easy for pets to use. I have two cats who have never had a problem with the doors. I will continue to purchase these pet doors, as they are far superior to any others I have seen.

    (Posted on 2/15/2013)

  • A quality product that works as advertised review by ChrisR
    5 5 A quality product that works as advertised

    Easy installation and good fit. We were not sure if our smaller 9lb cat would be able to open the flap as the magnets seem quite strong. We ended up putting two layers of masking tap on the bottom bar and that eased things nicely. No problems training our cats to use the flap - holding their favorite toy/treat on the other side quickly overcame any caution.

    (Posted on 2/11/2013)

  • Follow up to a review I posted 10/26 review by KateF
    5 5 Follow up to a review I posted 10/26

    I purchased a Thermo Sash IIIE cat door for sash windows. As I mentioned in my first review, It will pay for itself in one winter with the savings I will realize on my utilitiy bills. However, I also mentioned the sliding security door would not work because of a lip that protrudes on my window. To follow up on this - last weekend I ran that locking pet door through a table saw with a new "general construction" grade blade . The door is now exactly 6 and 7/8ths inches wide. I can now side-load the door, settle it into the bottom rail and then slide it back to center where the lock holds it securely in place. I easy solution if you're the handyman ( or woman ) type! I love my door!

    (Posted on 12/15/2012)

  • Insulated pet door review by Bob
    5 2 Insulated pet door

    Although the flap is innovative and works well, the surround is aluminum and is not insulated at all. In a cold climate, it weeps condensation continuously. It was not a simple fit with our particular vinyl windows that have a small ridge at the bottom of the frame. Also, only one side fits the side of the frame where it fits into the channel. The other side is too big, resulting in a small gap from top to bottom. The weather stripping supplied was in excess of what was needed and it too was only effective in the the solid part. There is no surface to run the weather strip over the area that is adjustable resulting in about 1/5th with no weather stripping. I will probably return it and order just the door and make my own insulated panel that won't look as nice but up hear near Chicago we need something that is actually insulated.

    (Posted on 11/24/2012)

  • Best Investment You'll Ever Make! review by KateF
    5 5 Best Investment You'll Ever Make!

    Gotta admit, when comparing Pacific Patio's prices with doors you can get at various retail outlets, I was a bit leery. However, after replacing my cat door for the third time in as many years, I was in a bit of a huff, Not to mention, with rising heating costs coupled with reduced income - I had to do SOMETHING! I ordered it Sunday night. It was on my doorstep Thursday morning. I had it set up in less than ten minutes. Then another ten minutes to add all the weather stripping that comes with the door. It was REALLY blowing hard the day I installed this door. I had to smile as I watched the curtain over the window. It never moved! Not even a fraction of an inch! This window is THAT weather tight! This window will pay for itself in one winter on the money I will save on my heating bill.

    On the downside - My sash window has a lip the protrudes out about an inch over this new pet door on the inside. Because of that - the locking cover will not slide downward in it's tracks. My fix for this - I took a scrap piece of vinyl siding and trimmed it to fit tight in the tracks. This siding has just enough bend to it, I can squeeze it into place yet it's still stiff enough my cats can't pull it out. I consider this a truely minor inconvenience in the face of this door's outstanding quality. I was looking for weatherproof. I got weatherproof!

    Surprisingly, I sent a feedback email to Pacific Patio letting them know how pleased I was with their product. I mentioned the issue with the locking cover. They assured me - they are aware of the problem and are working diligently on finding a solution.

    Even still - This door is the best investment you will ever make! If you'd care to email me I can send you pictures of mine.

    (Posted on 10/26/2012)

  • Just ordered my second door review by Big Daddy
    5 5 Just ordered my second door

    In 2003, we purchased our first thermo-sash door and it has been working ever since. We have just purchased a second home and have ordered one for that home. I could not ask for anything better to serve our needs. We've had 3 dogs over these years and all have mastered the door within the 1st or 2nd day. The puppies, Smith & Wesson, just love it and are trying to wear it out expressing their freedom.

    (Posted on 10/22/2012)

  • Awesome addition!! Don't question it, just pay for it!! review by Kenny
    5 5 Awesome addition!! Don't question it, just pay for it!!

    I bought the Thermo-sash IIIE when we moved into our house 6 years ago. We had one very tall chocolate lab at the time of purchase and now have a "normal" sized yellow lab as well, 87 & 65lbs each. They both use the door without hesitation, training took a handful of treats.
    They often hunt squirrels from inside the AC while looking through the window portion and then with a running start they leap "FLY" through the door out into the back yard. 6 years of doing this and the only thing I've had to replace were my wood floors from their peeling out prior to takeoff... This was by far worth every penny, since we were paying a pet sitter per visit to come over and let them out. I have told many of my friends with dogs about this item. Retail store dog doors vs this item is just flat out apples and oranges!

    (Posted on 9/2/2012)

  • Great Product! review by Janet D.
    5 5 Great Product!

    Thank you for a great product! In December 2011, I purchased the Thermo Sash Pet Door with the Endura Flap. It fits perfectly and is energy efficient. It was easy to install and the window and endura flap are both of high quality. My husband and I are so pleased. Most of all, our cat Phoenix and dog Dixie enjoy their new- found freedom! Training took some patience, but now they are both using it daily. Thank you customer service for training suggestions.

    (Posted on 4/5/2012)

  • I am extremely happy with my pet door and buying experience review by Ellen D.
    5 5 I am extremely happy with my pet door and buying experience

    I bough the ThermoSash IIIe #10 last March. True to the description on the website, it was very simple to install. I could even do it myself without any help from my neighbor or a handyman. I have an 80 lb. German Shepherd Dog who is active and always on the alert for unauthorized activity in the backyard. She runs in and out all day long. The unit is just perfect. It is sturdy and holds up to regular use. The seal is very secure and did not let any of the 100+ degree Texas heat in during the Summer months. It is easy to keep clean and is not an eyesore in my bedroom where it is installed. Your order and delivery service was great too. Although the unit was on backorder when I placed my order, it was shipped out 8 days later.
    I am extremely happy with my pet door and buying experience and wanted to share that with you.

    (Posted on 11/12/2010)

Weight 23.0000
Manufacturer Endura Flap
Your Maximum Pet Size Cats, Large Cats, Small Dogs, Medium Dogs, Large Dogs, X-Large Dogs
Type of Window Sash (Up & Down)
Climate Suitability Severe-4 Season
Sealing Value Very High
Wind Resistance Very High
Frame Material Heavy Extruded Aluminum
Employs Patented “Endura Flap” Yes
Insulation Value High
Possible to Add Additional Magnets for Greater Wind Resistance Yes
Flap Material Engage
Flap Design Single, One Part , Flexible, Insulated Flap
Flap Colors Clear
Flap Thickness 7/8"
Award Winning Design Yes
Replacement Flaps Available Yes
Flap Warranty (if separate) 15 years
Dual or Single Pane Dual Pane
Low “E” Coating Yes
Ability to Lock Flap Separate Locking Cover-Loads from Top
Locking Cover Material Dimensional ABS
Can Be Installed In Sash Windows
Warranty Period 15 years
Return Period 90 days (except for custom height ranges)
Manufacturer's Restocking Fee None

Design of the Endura Flap™



Adjusting Magnet Strength for Training




Leaf Blower Test


Installing the Thermo Sash 3e


Replacing the Flap in the Sash Pet Door


Switching the Flap Side



Installation Instructions for the Thermo Sash 3e Pet Doors for Sash Windows


1x Window pet door

1x Foam Weather Strip

1x Center Post Weather Seal Draft Stopper



1Loosen the thumb screws at the end of the sash. This allows the spring mechanism to move freely side to side.

2. Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the thumbscrews.

If the pet door sits properly, remove the pet door to put on the foam weather-stripping in step 3.

3. Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the panel, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.

4. Mount the draft stopper vinyl weather strip. This strip prevents air leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.



For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window.

For a temporary lock, place a removable wooden dowel or charley bar in either track above the window.



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. 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 thumb screws.Replace the end spacer and screws.



Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1” (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.



For help with installation, replacement parts or other questions visit or call 805-781-7700 Monday-Friday 7am-4:30pm PT



Click below to expand:

Four things:

  • What size pet door your dog or cat will need
  • How high you can raise the window (will it raise high enough to fit the pet door size you selected)
  • The width of the window (from the deepest part of the left track to the deepest part of the right track)
  • The width of the track (must be at least 1" to accommodate the Thermo Panel)

You will want to know the width of your pet and the height of your pet's shoulders. Your pet should fit without touching sides and the top of the pet door should clear your pet's back by at least one inch. Take a look at our measuring guide here.

The Thermo Sash includes the patented Endura Flap Pet Door which has a dual-layered flap employing magnets around the edges for superior sealability and insulation. It uses dual-pane, LoE glass for added insulating properties. Both of these are housed in a sturdy aluminum frame. It is made in the USA and backed by a 15 year warranty.

A minimum of 1 inch.

All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range.

Yes you can switch the side the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you’re finished. You'll want to make sure the thumb screws and locking cover are on the same side.

You can make it 3/4" inch smaller by trimming the right side (spring loaded piece). If this is not enough, we may be able to make a custom width with less or no glass. Please call us with your specific needs for us to review the possibility.

None. The Thermo Sash is installed without the use of tools. If desired, you may need tools to install a locking device to secure your window. Take a look at the Installations Instructions and Videos tab above.

It varies based on the pet door size: Small is 19", Medium is 23", Large is 27" and Extra Large is 31" high.

We make a width adjustment which extends the width by 3/4". You can order one here. You could also cut, paint and use a small piece of wood to extend the width.

The Thermo Sash does not have an adjustable height. The height of the unit is determined by the height of the pet door.

The most energy efficient one is the Thermo Sash 3e Pet Doors for Sash Windows.

The Thermo Sash iiie pet door is the most energy efficient pet door window insert on the market.

There is a vertical version of the Thermo Sash called the Thermo Panel. I is available in the same four flap sizes. It has three standard height ranges. If your window is shorter, a custom panel can be made.

Yes! The Thermo Sash is designed for windows that lift up and down. The Thermo Panel is designed for windows that slide left to right. Both are available in Custom sizes.

Yes. We've seen many creative ways to help our dog access the window. Pet parents usually install steps or a ramp on both sides of the window to the doggy access the window. This may require training, but can be successful.

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Patio Pacific Inc Endura Flap™ Pet Door Warranty

To the original purchaser, Patio Pacific Inc warrants this product and all of its component parts to be free of defects in materials or workmanship for a period of 15 years from the date of delivery to the customer.

Endura Flap™ assemblies are warranted for a period of 15 years. Endura Flap™ assemblies employed in commercial kennels are warranted for a period of 3 years.

Damage caused by accident, improper installation, abuse or normal wear, including damage by pets or glass breakage, is specifically excluded from this warranty.

Defective materials returned to Patio Pacific Inc, together with proof of purchase, will be repaired or replaced and returned to the customer free of charge.

Pet doors of other manufacturers installed in Patio Pacific products are covered by the warranty of the other manufacturer and not by Patio Pacific Inc.