Cat flap draughts: how to keep the cold out this winter

A cat flap and a warm home can live together, but a cat flap is still an opening in your door: a little air always gets through. To limit draughts, fit it in a door that does not open onto a heated room, seal its frame well, keep a flap edged with a seal, and lock it shut in very cold weather.

Does a cat flap let the cold into the house?

Yes, a cat flap lets a little cold air in, whatever the model. The Government of Quebec even lists the cat flap, alongside the letterbox, among the places to inspect when tracking down air leaks in a home. All the more reason to choose carefully where and how you fit it.

Cold air comes in at three points. First through the small gap between the flap and its frame, all the time. Then through the frame itself, if it sits loosely in the cut-out. Finally each time your cat goes through, when the flap swings wide open.

The first point depends on the model; the other two depend on you. According to the same Quebec page, air leaks greatly reduce the comfort of the people living in a home and push up heating costs. The gap left around a loosely fitted frame is one of them.

Where should you fit a cat flap to limit draughts?

When it comes to the cold, where you put a cat flap matters more than which model you choose. It is best to avoid a door or window that opens straight onto a heated room, and to choose a cellar or garage door instead, sheltered from wind and weather.

Whatever air gets past the flap is then lost in a space you do not heat, rather than reaching the living room. And a door sheltered from gusts sees its flap knocked about less, so it sits ajar less often.

If the only door you can use opens onto the room you live in, bear in mind that the Pelux 4-way locking cat flap has a single flap: it locks both ways, but it does not form an airlock. The last section explains when another model is the better choice.

A brush seal all round the flap
Its clear flap is edged with a brush that limits draughts when nobody is coming through, and its "locked both ways" setting shuts the opening on bitterly cold nights. Discover the 4-way locking cat flap →

How do you stop an existing cat flap letting the cold in?

An existing cat flap gets less draughty when you deal with its surround before its flap. According to the Government of Quebec's page on doors and windows, heat lost through a door or window often comes down to the way it was installed; to deal with draughts, sealing the gap between its frame and the wall often pays off more than replacing it. The same logic applies to a cat flap frame.

1. The hand test. On a windy day, run your hand around the frame on the inside. A thread of cold air means a leak.
2. The frame surround. If air gets between the frame and the cut-out, a sealant suited to what your door is made of closes the gap, as long as it stays clear of the flap.
3. The flap seal. Pick out the cat hair caught in the brush or seal, and check that a doormat is not catching the flap: if it does not drop fully closed, it leaves a permanent gap.
4. The locked setting. In the evening, once your cat is home, lock the flap both ways.

One limit to all this sealing: never block a vent or an air inlet in the room to make up for it. On its carbon monoxide page, sante.fr, the French public health information service, asks people to air their home every day and never to block its air inlets and outlets.

If you lock it at night, put a litter tray indoors. And if your cat goes out in all weathers, also check at what temperature letting your cat out in winter becomes questionable.

Insulated double-flap cat flaps: when are they the better choice?

A cat flap sold as insulated, with a double flap, is designed to hold back air better than a single flap, which matters in a very exposed house. Its two flaps form a small airlock: cold air has to get past two barriers instead of one.

The Pelux cat flap is not that kind of model. It has a single flap edged with a brush, and its product page states no measured insulation performance. It belongs on a garage, utility room or back door, or in a home that is not very exposed.

For a front door that opens straight onto the living room, a wall facing the full force of the wind or a region with long winters, choose a double-flap model sold as insulated.

For the rest of the house, the winter fixes on your cat's side stay the same: a bed suited to the season, away from doors and draughts. The cat flap and the rest of our safety kit are gathered in the safety and care range.

Frequently asked questions

Can you put a draught excluder or a curtain in front of the cat flap?

Only once the cat flap is locked both ways and your cat is home. In front of an open flap, a draught excluder blocks it, and a curtain hides what the clear flap lets your cat see before pushing through. A flap that rubs against either also stays ajar. Take them away in the morning, before you open the flap again.

Can the wind blow a cat flap open?

A cat flap that faces the prevailing wind can see its flap move. The product page for the Pelux cat flap mentions no magnet or weight to hold it closed, so we will not promise you it stands up to gusts. On stormy days, the "locked both ways" setting settles the matter.

Should you keep the cat flap locked all winter?

No, locking it only at the coldest times is usually enough: at night and on frosty days. During the day, if your cat is used to going out, the open or "in only" setting lets them choose to come back in and warm up. For an elderly, unwell or very chilly cat, ask your vet whether they should go out in winter.

Key takeaways

• A cat flap is always a weak point in a door: a little cold air gets through, whatever the model.
• For keeping the cold out, location matters more than the model: a cellar or garage door, sheltered from the wind, keeps outside air away from heated rooms.
• On a fitted cat flap, seal the frame surround first, clean the flap seal, and lock it both ways in very cold weather, without ever blocking the room's ventilation.
• For a very exposed house or a door that opens onto the main living space, a double-flap model sold as insulated will do better than a single flap.