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How to Fit a Fly Screen on a UK Window or Patio Door

Updated: 15.10.2026

You are fitting a screen to a uPVC window or a patio door, and the next cut is the one you cannot take back. How to fit a fly screen, once the type is chosen, comes down to the position, the measurement, and the point where you stop. The Products Compared editorial team drew this from Windhager's public fitting notes and UK amazon.co.uk reviews in the [insect screen comparison](/hub/garden-supplies/windhager-insect-screen), captured on 15 October 2026. There was no laboratory fitting, and no screw layout came from the assembly portal. If the type is still open, use the [fly screen buying guide](/hub/garden-supplies/windhager-insect-screen/sub/windhager-insect-screen-buying-guide) before you mark a length. A qualifying purchase can earn a commission at no extra cost to you.

You are fitting a screen to a uPVC window or a patio door, and the next cut is the one you cannot take back.

Our top picks

tesa UK tesa Insect Stop Standard 110 x 130 cm

Best overall

tesa UK tesa Insect Stop Standard 110 x 130 cm
8.6/10about £6.97
View offer
tesa UK tesa Insect Stop Standard 100 x 100 cm

Preis-Tipp

tesa UK tesa Insect Stop Standard 100 x 100 cm
8.4/10about £2.56
View offer
Windhager Windhager magnetic window kit, 100 x 120 cm

Alternative

Windhager Windhager magnetic window kit, 100 x 120 cm
6.0/10about £26.23
View offer
On this page
  1. 1.Where the screen will sit
  2. 2.What to measure before you cut
  3. 3.Sheet, magnetic kit, or sawn frame
  4. 4.Stop before you cut

Where the screen will sit

The screen fills the opening, overlaps the frame face, or spans the reveal, and each position uses a different number. Clear measure is the hole inside the open frame. Reveal measure is the gap between the wall faces. On a UK uPVC casement the handle sits on the room side, so an inside fit has to clear that lever with the window shut. Cut to the glass size for a reveal, and the screen stops short of the walls. Label the first figure clear or reveal before you go further.

What to measure before you cut

Record the width, the height and both diagonals before you cut a rigid frame. The diagonals show whether it is square. Where the diagonals differ, a shorter rail only moves the slit along. A tesa sheet can skip the diagonals, because you are not locking four mitres. You still need the width and the height, and you shut the window on the mesh before the last trim so the handle has slack. A patio opening can match at the top and still fail the diagonals. Leave the hacksaw in the box rather than average them.
tesa UK tesa Insect Stop Standard 110 x 130 cm

Testsieger

tesa UK tesa Insect Stop Standard 110 x 130 cm
8.6/10about £6.97
View offer

Sheet, magnetic kit, or sawn frame

Scissors cut a tesa sheet or a stretch sheet. The top pick, titled 110 x 130 cm, and the best value at 100 x 100 cm are both scissors jobs. MiLeJu, NeatiEase and BITOYO are not saw jobs here. The Windhager plastic-profile kit needs a hacksaw and a mitre box. UK tesa reviews found painted wood a weaker hold than sound plastic. A short magnetic strip on a MiLeJu kit should stay short, because the red release tape can lift the adhesive. Shut the window or door on the mesh before the last trim. In a UK Expert-door review the handle hit the mesh, and a gap remained after a timber packer.

Stop before you cut

Leave an incomplete kit uncut, and leave a rigid frame uncut if the diagonals differ. No screw pattern came from the assembly portal, so a missing leaflet means you stop rather than drill the uPVC from memory. The mesh will not hold a child. Where a fall from an upstairs window is the risk, fit a restrictor. Approved Document K is England's guidance on that risk, and Scotland, Wales and Northern Ireland sit outside it. Hand an out-of-square frame, or a fit that means leaning out, to a window fitter. If the box is the wrong family, go back to the buying guide before a saw is used to force a change.

Common questions

Do I measure the glass or the frame?
Measure the opening the screen will occupy. The pane is a different figure from the clear hole inside the frame and from the reveal between the wall faces. Bead and frame take a margin off the glass, so an old pane size is a poor length to cut. Write clear or reveal on the number, and measure the frame again if the glass size is all you have.
What is a reveal measure?
A reveal measure is the wall-to-wall distance around the window or door, which differs from the inner edges of the frame. Use it when the screen spans that recess. It often parts company with the clear opening because the frame sits inside the wall. For a screen that drops inside the frame, record the clear opening, and choose the fixing face before you write the number down.
Can I fit a fly screen without a hacksaw?
Scissors suit a tesa sheet and a stretch sheet, and MiLeJu, NeatiEase and BITOYO are not saw work here. A plastic-profile window or an aluminium door still needs a hacksaw and a mitre box. Windhager's notes add gloves and tell you to seat the spline without extra tension. Scissors leave an aluminium corner unmitred.
What if the door handle hits the mesh?
Shut the window or door on the mesh before the last trim, and leave slack for the handle, as UK NeatiEase reviews do on a closed window. In a UK Expert-door review the handle hit the mesh, 60 x 30 mm timber packed the frame out, and a gap remained. The packer can clear the plastic, though insects will use the gap.
How do I avoid cutting the mesh short?
A fly screen mesh cut too short cannot be stretched back into the groove. Set the frame or the tape, shut the real window or door, then trim. UK reviews of listing B078KKWCH3 and of Rhino-titled frames found the mesh already short, and a mallet adds no cloth. Keep a short magnetic strip short, because on MiLeJu kits the red release tape can lift the adhesive.
Will 14 mm or 16 mm clear a window handle?
A depth of 14 mm or 16 mm does not mean the handle will clear the mesh. A UK Expert-door review had the handle hit the cloth, then a 60 x 30 mm timber packer, and a gap still left. Measure from the fixing face past the closed handle, with the window shut. If the handle stands proud of the frame in the box, change the face or the type before you cut.

Related pages

Fly screen for a patio door

Magnetic or hook-and-loop

Insect screens

Best Windhager Insect Screen for the Opening You Have

Fly Screen Buying Guide UK: Window Sheet, Kit or Door

Sources

Public UK and manufacturer sources used for this comparison; last accessed 15 October 2026.

  1. Consumer Rights Act 2015, section 9 (satisfactory quality) (retrieved 15 October 2026)
  2. Consumer Rights Act 2015, section 11 (goods to match description) (retrieved 15 October 2026)
  3. CAP Code, section 3 (misleading advertising) (retrieved 15 October 2026)
  4. Approved Document K: protection from falling, collision and impact (retrieved 15 October 2026)
  5. Office for Product Safety and Standards (retrieved 15 October 2026)
  6. NHS: insect bites and stings (retrieved 15 October 2026)
  7. Windhager FAQs (retrieved 15 October 2026)
  8. Windhager: insect protection fitting tips (retrieved 15 October 2026)
  9. Highland midge (Wikipedia) (retrieved 15 October 2026)