Guide · · 4 min read
Do cat doors let the cold in? Draughts, winter and how to keep the heat
A well-made cat door that is fitted properly lets in very little cold. When one is draughty, it is usually the fit, a worn flap or a clip-in panel. Here is how to keep the heat in.
By the Pet-Tek International team, Auckland — designers of Catwalk® and Dogwalk® since 1999.
It is the first thing many people ask in a New Zealand winter: if I put a hole in the door, am I heating the garden? The honest answer is that a well-made cat door, fitted properly, lets in very little cold. When one is draughty, there is nearly always a fixable reason.
What keeps the cold out
- A brush seal. Every Catwalk® and Dogwalk® flap closes against a full brush seal, which blocks the gap between flap and frame.
- A magnetic catch. Magnets at the base hold the flap shut, so it does not swing or rattle in the wind and settles closed after your pet goes through.
- A sealed fit. In glass, the two frame halves clamp through the hole with a gasket. In a wall or thick door, the tunnel lines the opening so there is no open cavity.
- A small opening. A cat door is a small panel in a much bigger door or window, and it is closed for all but a few seconds at a time.
Why some cat doors are draughty
A worn flap
Flaps get scratched, cloudy and slightly bent over the years. Once a flap stops sitting flat, the seal stops working. The fix is cheap: replacement flaps are stocked for every current Catwalk® and Dogwalk® door and most older ones, and they swap in without taking the door out. Browse them in spares and accessories.
A poor fit
A cut-out that is too big, or frame screws that were never fully tightened, leave a gap around the frame. Check by running your hand around the edge on a windy day. On a wood-fitting door, tightening the screws usually closes it.
A clip-in panel
Pet door panels that stand in a slider’s track are the draughtiest option of all: the slider can no longer close against its seal, and air gets in around the panel. A door fitted in the glass keeps the slider closing and sealing as normal; see our ranch slider guide.
A windy spot
If the door faces straight into the prevailing wind, gusts can lift any flap. Where you have a choice, put it on the sheltered side of the house.
Double glazing and the cat door
If your home is double glazed, you may worry that cutting it ruins the insulation. It does not, because nobody cuts your existing unit. The glazier orders a new sealed unit with the hole made at the factory, so the gap between the panes stays sealed, and the pet door clamps through it. The Catwalk® Maxi Dual Glaze takes glass up to 28 mm and the Dogwalk® Medium Dual Glaze up to 32 mm. More in our double glazing guide.
Thick doors and walls
On a solid or thick door, a cut-out with no lining leaves raw timber or a hollow core open to the weather. A tunnel model closes it: the Catwalk® Cat Door Tunnel and Dogwalk® Small Dog Door Tunnel line openings up to 52 mm, and through a framed wall the opening is lined before the door goes in (see through-wall dog doors).
Winter habits that help
- Lock it when it is not needed. Set the 4-way dial to locked overnight; it is safer for your cat too (keeping your cat in at night).
- Close the heated room. An internal cat door in the hallway or laundry door lets you shut the cold part of the house off without shutting the cat out.
- Keep other cats out. A flap that only opens for your cat, like the Catwalk® Multi-Magnetic, is opened less often.
- Check the flap each autumn and replace it if it no longer closes firmly.
Choosing a door for a cold spot? Find your door, read how to choose a cat door, or email a photo of where it is going to info@petnest.co.nz.
Quick answers
Do cat doors let the cold in?
A good one, fitted properly, lets in very little. Catwalk and Dogwalk flaps close on a magnetic catch against a brush seal, so they sit shut and do not swing in the wind. Most draughts come from worn flaps, gaps around a poorly fitted door, or clip-in panels.
How do I stop a draught from my cat door?
Check the flap closes flat against its seal; a scratched, warped or cloudy flap can be swapped for a replacement without removing the door. Make sure the frame is tight with no gaps around the cut-out, set the dial to locked when the door is not needed, and avoid clip-in panels in sliders.
Does a cat door in double glazing lose heat?
Very little. The glazier supplies a new sealed double-glazed unit with the hole made at the factory, so the unit stays sealed, and the pet door's frames clamp through it with a gasket. Only the flap area itself is single-layer.
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