Fitting a cat flap in a door: the height, the tools, and why you mark it out from the flap itself

To fit a cat flap in a wooden door, measure the height of your cat's belly from the floor, mark out from the cat flap you receive, drill the corners, cut with a jigsaw, sand and screw the frame in place. The cut-out size for the Pelux cat flap has not been given yet, so never cut from a figure found online.

What height should a cat flap be?

The height of a cat flap is taken from your cat, not from the door. Zooplus's guide advises measuring the distance between its belly and the floor and, with several cats, going by the smallest one.

Measure your cat standing still. That level gives the sill of the opening, the part it steps over. Because the frame overlaps the cut-out, hold the cat flap itself against the door to place that sill before marking anything.

Why mark out from the cat flap you receive rather than from a measurement?

Because the cut-out size is not always given, and a figure borrowed from another model is enough to ruin a door. That is the case with the Pelux 4-way cat flap: its supplier does not give the cut-out size as such, only the measurements of the inner panel, and no cutting template is listed in the box. The product page says so: wait until you have it in hand before marking out.

Zooplus's guide starts from the template that comes with most cat flaps. Without one, the cat flap itself does the job: hold it where you want it, measure the part that goes through the door on the flap itself, then mark out in pencil.

Before you order, check how thick your door is: up to 50 mm according to the supplier, with no breakdown by size. The M and L are 5.5 cm deep overall; for the S, which is flat (1.8 cm), the door thickness it takes has not been given yet.

Mark out from the flap, then set the direction
Once it is fitted, two sliders at the base of the flap, one red and one green, let you choose in only, out only, locked both ways or open. Discover the 4-way cat flap →

What tools and steps do you need to fit a cat flap in a wooden door?

A solid wooden door needs only an ordinary tool kit: tape measure, pencil, drill, jigsaw, sandpaper and screwdriver. The order follows Zooplus's guide: drill holes at the corners, saw, sand the corners, check that the flap opens and closes properly, then screw it in from the inside.

For the Pelux cat flap, the supplier's photos show screws and screw covers; the product page says no more, so have screws suited to your door ready if needed.

Moulded door, uPVC door: what changes?

A door with mouldings first needs the area cleared: the frame has to sit flat. On Forumconstruire, one homeowner describes sawing through the moulding on their wooden front door at the edges of the cut-out, then failing to knock it off with a mallet; other members suspect it is glued. In the end, they prised it off with a wood chisel, with the door off its hinges and laid on trestles. Check how yours is fixed before you saw.

To fit a cat flap in a uPVC door, the only criterion the Pelux product page lets you check is thickness: up to 50 mm according to the supplier. It makes no distinction between wood and uPVC. A uPVC door may hide a reinforcement or a hollow panel: only its manufacturer, or a joiner, knows where it can be cut.

When is a cat flap in the door not the right answer?

Do not cut if your door falls into one of these cases:

• Glass door or patio door: the supplier of the Pelux cat flap says nothing about glass or double glazing.
• Metal door: nothing on the product page says it can be fitted there.
• Door thicker than 50 mm: beyond what the supplier states.
• uPVC door with a metal reinforcement that your joiner advises against drilling.
• Rented home: cutting a door alters the property, so you need your landlord's written consent first.

Before you open the door, think about the other side: the dangers outdoors for a cat vary from one neighbourhood to the next, and a secure outdoor space changes a great deal. The safety and care family gathers what goes with the cat flap.

Frequently asked questions

Do you need to take the door off its hinges to fit a cat flap?

Not necessarily: Zooplus's guide finds it easier to saw with the door left closed. Take it down if it moves too much or if a moulding has to come off first: laid flat on trestles, it is easier to work on. If it is heavy, get help.

Should you call a joiner?

For a solid wooden door, a well-equipped DIYer will manage. Call a joiner as soon as you do not know what is inside the door (hollow core, reinforcement), for an insulated front door, or if the moulding will not budge: they will tell you whether the cut is possible.

What size of cat flap for two cats of different builds?

For the height, go by the smaller one. For the size, the supplier of the Pelux cat flap recommends the S for a cat under 4 kg, the M under 5 kg and the L under 6 kg, but doesn't give the opening itself. Only the L has a larger face (23.5 × 25 cm); the S has the same face as the M (19 × 19.7 cm), only flat.

Key points

• The height of a cat flap is taken from the distance between your cat's belly and the floor, and from the smallest cat if you have several.
• With no cut-out size and no template, mark out from the cat flap you receive by holding its frame against the door: once a door is cut, there is no going back.
• The fitting order: mark out, drill the corners, cut with a jigsaw, sand, check that the flap opens and closes, screw in, then set the direction.
• Glass, metal, thicker than 50 mm, or uPVC with a reinforcement a joiner advises against drilling: a cat flap in the door is not the answer.