So you want to have a beautiful house AND take care of your beloved pets? In this article we’re going to round up the best options when it comes to cat flaps in double glazing.

And it’s not just limited to cats; they are available for a whole range of animals, with dog flap doors being another common request.

These devices can indeed be incorporated into any style of door; timber, composite, aluminium or UPVc or glass unit successfully and without compromising the huge benefits that double glazing offers.

Types of dog and cat flaps

Whether you’re looking to get a cat flap or dog flap fitted in a glass unit or a panel, there are various options.  

The most basic cat or dog flap is the four-way locking system

This controls the opening of the door with both entry and exit movement, locking entirely or a one-way operation.  Whilst door flaps can be purchased in most DIY stores or pet shops, it is best installed into double glazing by your professional installer.

The microchip dog or cat flap door recognises your animal’s unique microchip implant, ensuring only your pet uses the doorway, blocking the way to neighbour’s pets and strays.  Some even have a ‘curfew mode’, enabling it to be programmed to lock and unlock at specific times.   

Cat flap installation for composite and aluminium doors are totally possible, but will need careful attention as the metal can potentially interfere with the microchip reader.

The magnetic/electromagnetic cat and dog flap is operated via a magnet on your pet’s collar. 

These also ensure that no other dogs or cats gain entry to your home, but watch out: they are not suitable for double-glazed doors containing metal (and even some UPVc units contain hidden reinforcing metal).  Check first with your supplier.

The infrared cat or dog flap is also operated  by contact with the animal’s collar which contains an infra-red key. 

Whilst the ‘key’ is fairly unique, there may be as many as four unique codes per collar so potentially a neighbour’s pet could carry the same code.

Can I find a dog or cat flap to suit the size of my pet?

Whilst there are standard sized dog and cat flaps, extra large ones are available for pets who need a more generous gap.

Check with your double glazing manufacturer as to the range of sizes they offer and discuss which would most likely suit your pet.  

As a broad size guide:

  • Conventional cat flaps: 195 mm (w) x 185 mm (H)
  • Microchip cat flaps: 142 mm (W) x 120 mm (H) up to 178 mm(W) x 170 mm (h).
  • Dog flaps: 270 mm (W) x 300 mm (H)

Incorporating a pet flap into a double glazed door or window

Incorporating a cat or dog flap into your double glazed home is easy.  However, cutting into toughened glass will only cause the unit to shatter.  

Cutting into double glazed units will also destroy the seal so this means that double glazed glass units need to incorporate the pet door at the time of manufacture.  

In terms of budget cat flap fitting, it is possible to purchase your own and ask your tradesman to install it for you if cost is an issue. 

Check your guarantee for this however, as a poor quality animal door could cause units to mist up. 

You’ll need to know who, in this case, is responsible and if your guarantee stands.

When your pet flap is incorporated at the time of manufacture, a hole is made in the glass specially to accommodate it (ensuring an air-tight fit later).  

This allows you to benefit from the thermal efficiency and noise reduction that you’d expect from double glazing.

Once the glass for the window or door has been toughened, and correctly-sized, pre-holes added to each piece. It is then manufactured into a double-glazed unit

Your bespoke unit is fitted at your property and the addition of the cat or dog flap installation can be made.  

When replacing an existing glass window for a double glazed unit with a pet flap, the process could take as little as 4- 5 working days from measure to supply. 

For timber, composite or UPVc doors with panels, the hole into which the flap is fitted, is usually cut on site provided the surfaces are flat. 

Note: It’s often not recommended to cut cat flap holes in decorative panels as this is prone to ‘gapping’.  

Will my cat flap cause a draught?

Homeowners often worry about this. 

Understandably, nobody wants to spend large amounts on double glazing their home only to find the pet flap is allowing a draught into the house.

The design of dog and cat flaps ensure that, once in situ, the seal is air-tight.  Using a qualified double glazing fitter, with the correct tools, will give you added peace of mind.

So, banish that cat litter tray and frequent meowing whilst your cat waits to be let out.  Allow yourself peace of mind knowing that your much loved pet can have the freedom to come and go as they please and enjoy important exercise whilst you get on with life.  

Our stylish homes need not be at the expense of our cherished pets but instead, encompass our whole range of lifestyle choices!

Looking for more ideas for double glazing? Check out all our guides to choosing windows, doors and conservatories.

Matt James
Matt James

Hi, Matt here! I started out almost 20 years ago as a teenager working in the family business fitting doors, windows and conservatories. I now run this website to share the best tips and advice for anyone looking to get a good deal on double glazing.