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Quick answer
For low tunnels over vegetables for one season, 100–150 micron film is usually enough. For walk-in tunnels and greenhouses that must last more than one season, use UV-stabilised 200 micron film. Buy UV-stabilised film for anything that stays up through a summer, ventilate generously in the heat of Sindh and Punjab, and anchor the film well against monsoon winds.
Key takeaways
- Film is sold by thickness in microns: 200 micron = 0.2 mm.
- UV-stabilised 200 micron film is the standard for walk-in tunnels and greenhouses; 150 micron suits low and small tunnels.
- UV stabilisation decides how many seasons the film survives in strong sun.
- In summer, heat is the enemy: ventilate, and add 35–50% shade net over the film.
- Film width = the hoop measured over the top, plus a burial allowance on both sides.
Film thickness in microns
Greenhouse film is sold by thickness in microns (µm). One micron is a thousandth of a millimetre, so 150 micron is 0.15 mm and 200 micron is 0.2 mm. Thicker film resists tearing, hail and wind better and usually lasts longer, but costs more per square metre.
| Structure | Typical thickness | UV stabilised? | Notes |
|---|---|---|---|
| Low tunnel (over beds, knee to waist high) | Thin film for one season, or 100–150 micron to reuse | Recommended if it stays up past spring | Easy to vent by lifting the sides |
| Walk-in tunnel | 150–200 micron | Yes | 150 for budget, single-season crops; 200 for a longer life |
| Greenhouse or multi-span | 200 micron | Yes — ask for a multi-season grade | Fix with lock channel and wiggle wire, not nails |
| Mulch over beds | 20–30 micron, black | Not usually | Blocks weeds and holds moisture under drip lines |
Why UV stabilisation matters
Ordinary polythene breaks down in sunlight: it yellows, turns brittle and tears. UV-stabilised film contains additives that slow this down. Across most of Pakistan the sun is strong for much of the year, so un-stabilised film may not last a single summer outdoors.
- Buy UV-stabilised film for anything that stays up through a summer.
- Ask how many seasons a grade is rated for. Longer-life grades cost more but save a re-cover.
- Film touching hot metal ages fastest — tape or paint pipe frames white where the film rests on them.
- Sprays containing sulphur or chlorine can shorten film life; avoid spraying them onto the film.
Other film features worth asking about
- Anti-drip (anti-fog)
- Condensation runs down the film in a sheet instead of dripping onto plants, which means fewer leaf diseases after cold, humid nights.
- Diffused light
- Scatters light so it reaches the lower leaves and reduces scorching. Useful for summer crops.
- Thermal (IR)
- Holds more heat overnight. Worth considering for winter vegetables where nights turn cold.
Not every roll has every feature, and each one adds cost. Tell us your crop and season and we'll tell you what is worth paying for.
Planning for Pakistan's climate
- Summer heat (May–August): a closed tunnel in Sindh or southern Punjab can overheat quickly on a sunny morning. Build in roll-up sides or end doors, and fit 35–50% shade net over the film at the peak of summer.
- Winter cold (December–January): in central and northern Punjab and in KP, tunnels protect vegetables from frost. Close them in the late afternoon to trap heat and open them on sunny days.
- Monsoon (July–September): expect strong gusts and heavy rain. Anchor the film along its whole length, keep it taut so water can't pond on the roof, and make sure run-off drains away from the base.
- Dust: a dusty film lets less light through. Rinse it with plain water when dust builds up.
How much film to buy
For a tunnel, measure the hoop over the top, from ground to ground, with a tape — not the width across the base. Then add a burial or fixing allowance on both sides.
Film width
hoop length + 2 × burial allowance (about 30 cm each side)
Example: A walk-in tunnel whose hoop measures 6.5 m from ground to ground needs 6.5 + 0.6 = 7.1 m of width. Choose the next roll width up, or ask for film cut to size.
Film length
tunnel length + 2 × end height + about 1 m for fixing
Example: A 30 m tunnel that is 2.5 m high needs about 30 + 5 + 1 = 36 m of film to cover both ends as well.
Installing the film
Prepare the frame
Smooth sharp welds and bolt heads, and wrap or paint the frame wherever the film will touch it.
Pick a calm, mild day
Wind makes film hard to handle. Film fitted on a cold morning can sag once it warms; film fitted in midday heat can be over-tight at night.
Check which side faces out
Some films are printed with 'this side out'. The UV-protected face must face the sun.
Fix it, don't puncture it
Use lock channel and wiggle wire, or wooden battens, along the edges. Nails and staples through the film start tears.
Tension evenly
Pull from the centre outwards until the film is smooth and tight, with no pockets where water can collect.
Bury the edges
On tunnels, bury the long edges about 30 cm deep in a trench and pack the soil down firmly.
Written by the team at Marfani Enterprises, Jodia Bazaar, Karachi. Figures are typical ranges for guidance — ask us about your exact job. Updated 27 September 2026.
