Fit a cat flap in a timber door — HomeGraft

Cut a hole in a timber door and fit a cat flap, checking the door type first and sealing the cut edges.

CF-01Check the door type and the kitMeasure the door thickness and check the cat flap kit is rated for it — most cover 25-45mm. Tap the door: a solid, heavy sound means solid or semi-solid timber; a hollow, drum-like sound means a hollow-core panel door with a cardboard honeycomb centre, which needs extra reinforcing later. If the door is a certified fire door (common on flats and between a house and integral garage), stop and check first.

RULES

KNOW THE RULES

Cutting a standard hole in a certified fire door removes its fire rating. Building Regulations Part B covers fire doors — only fit a cat flap using a kit specifically certified for fire doors, or get advice before cutting.

CF-02Take the door off and lay it flatUnscrew the hinges and lift the door off, or ask someone to hold it steady if you can't remove it. Lay it flat across two trestles or a workbench so the whole cutting area is supported underneath. Working flat gives a straighter cut and stops the jigsaw wandering.

2 each · Trestles or workbench

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CF-03Mark the hole using the templateUse the paper template supplied with the kit — most cat flaps sit with the bottom of the opening 25-70mm above the ground for an average cat. Centre the hole side to side, and check it lands in a flat panel, not over a stile, mid-rail or glazed section. Tape the template in place and trace round it, then check the lines with a spirit level and try square.

1 roll · Masking tape

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1 each · Pencil

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1 each · Try square

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CF-04Drill starter holes for the jigsawDrill a 6-8mm hole just inside each corner of the marked line. This gives the jigsaw blade a clean entry point and stops the corners splitting when you start cutting.

1 each · Drill bit 8mm wood

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CF-05Cut the holeFit a fine-tooth wood blade and cut slowly along the marked line, letting the jigsaw do the work rather than forcing it. Support the offcut from underneath as you finish the last side so it doesn't snap away and tear the surface. Wear a dust mask and safety glasses — cutting a panel door throws out a lot of fine dust.

1 each · Jigsaw fine wood blade

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1 each · Dust mask

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1 each · Safety glasses

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CF-06Reinforce a hollow-core door if neededIf the door is hollow-core, the cardboard honeycomb inside gives the screws nothing solid to grip. Cut strips of 12-16mm plywood to line the inside edges of the hole and glue them in place with wood adhesive, so there's solid timber all the way round for the flap's screws to bite into. Skip this step on solid or semi-solid timber doors.

1 set · Plywood strips 12-16mm

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1 bottle · Wood adhesive

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CF-07Test fit and ease the holeOffer the flap's tunnel section through the hole from one side. If it's tight anywhere, ease the edges back with a rasp or sandpaper rather than forcing it, checking the flap sits square as you go.

1 each · Rasp or sanding block

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1 sheet · Sandpaper medium grit

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CF-08Seal the cut edgesBrush wood sealant or varnish onto all the newly cut edges, especially on an exterior door or a hollow-core door. Bare cut edges soak up moisture and swell or rot over time. Let it dry fully before fitting the flap.

1 small tin · Wood sealant or varnish

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1 each · Small paintbrush

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CF-09Fit the cat flapSandwich the door between the inner and outer frame halves of the flap and insert the long screws supplied with the kit through both sides. Tighten evenly a little at a time, working round the frame, so the door isn't pulled tight on one side and left loose on the other. Don't overtighten — timber can crack, especially near the edges of the hole.

1 each · Cat flap kit

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1 each · Screwdriver

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CF-10Rehang the doorScrew the hinges back in and rehang the door. Open and close it fully to check the flap's tunnel doesn't catch on the frame or floor, and that the door still latches properly.

CF-11Set the flap's locking modeMost flaps have a four-way dial or switch: in-only, out-only, locked, or free access. If it's a microchip or collar-tag model, follow the kit's instructions to programme your cat's chip or tag now, before you test it.

2 each · Batteries (if electronic flap)

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CF-12Test with the cat and tidy upProp the flap open and encourage your cat through with a treat a few times before leaving it to close fully. Vacuum up all the sawdust from both sides of the door, wipe the frame down, and bag the door offcut for disposal.

1 each · Vacuum cleaner

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1 pack · Cat treats

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