Choosing polytunnel cover polythene for a walking tunnel
Updated: October 2026
You have measured the footprint of a walking tunnel and found a clear sheet whose area looks large enough. That is not yet a polytunnel cover polythene calculation: the material must travel over the hoops, reach the fixing points and leave enough at both ends. Our [greenhouse film comparison](/hub/raised-beds-greenhouses-and-compost/greenhouse-film) includes useful small sheets and patches, but none of its eight products is a made-to-measure tunnel cover. For a multi-season structure, size the skin to the frame and buy a thickness and UV term that the seller actually publishes.
You have measured the footprint of a walking tunnel and found a clear sheet whose area looks large enough.
You have measured the footprint of a walking tunnel and found a clear sheet whose area looks large enough. That is not yet a polytunnel cover polythene calculation: the material must travel over the hoops, reach the fixing points and leave enough at both ends. Our greenhouse film comparison includes useful small sheets and patches, but none of its eight products is a made-to-measure tunnel cover. For a multi-season structure, size the skin to the frame and buy a thickness and UV term that the seller actually publishes.
Our top picks
| Badge | Product | Stated size | Stated thickness | UV claim | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  GSHUR GSHUR 2 m × 2 m polythene sheet | 2 m × 2 m | – | No | 7.8 | about £7.99 | View offer |
 AGGAFA AGGAFA 150 µm greenhouse film, 2 m × 3 m | 2 m × 3 m | 150 µm (6 mil) | Over 4 years | 8.6 | about £12.99 | View offer | |
 Pumtus Pumtus 6 mil greenhouse film, 3 m × 8 m | 3 m × 8 m | 6 mil | No year | 6.8 | about £16.14 | View offer |
On this page
What a tunnel cover must span
Start by measuring the route the film follows, not the tunnel’s floor. For the main cover, that means the distance from one fixing edge, over the curved hoops, to the fixing edge on the other side. Measure along the curve with a flexible tape or cord rather than calculating from width and height unless the frame maker supplies the required cut size. Then measure the tunnel length and account for the way your doors and ends are finished.
Northern Polytunnels advises adding about 3 m per end when the cover fixes to door frames, with another metre of caution on a wider tunnel with doors at both ends. A cover equal to the bare tunnel length is not enough.
A 2 m width will not travel over most walking-height hoops and into both fixings.
The specification specialist tunnel firms publish
UK tunnel suppliers state their films in microns and attach a defined service term to named products. Premier Polytunnels lists 150 micron film with a four-year UV warranty and 180 micron film with a five-year warranty. Northern’s clear film is 180 micron with a five-season UK UV warranty. First Tunnels lists 200 micron Super Therm film with a seven-year UV guarantee.
The eight amazon.co.uk sheets do not meet that information standard as a group. AGGAFA states 150 µm and includes a line about more than four years in a bullet, but that line is not a separate warranty field and its model number conflicts with the selected size. GSHUR states neither thickness nor UV treatment. None should inherit a specialist supplier’s warranty simply because a similar thickness appears in a title.
For mil and weight, use the greenhouse film buying guide. For a tunnel purchase, require adequate cut dimensions, a stated horticultural gauge and a UV term you can verify.
The largest plainly stated sheet in this set
Pumtus B0FNBJYGGL states 3 m × 8 m, giving 24 m², and is the largest broadly proportioned piece in this comparison. It also states 6 mil. At £16.14, that combination can look like a complete tunnel-cover bargain.
The limitation is evidence. The UV claim has no year count, and the anti-drip bullet does not identify the treated face. The raw file contains seven reviews, only one of which is headed United Kingdom. That UK buyer called it good value but said the plastic was cut where it crossed cut cable ties. A US review says the plastic broke down within weeks.
Those comments prevent a confident multi-season recommendation. More importantly, 3 m may still be too narrow once it follows a walking tunnel’s hoop.
The CHESTAF review that mentions a polytunnel
One UK review says CHESTAF polythene was used to construct a large garden polytunnel. That does not settle the selected 2 m × 2 m option: the pool includes 2 m × 10 m sheets, and the listing’s URL ASIN differs from its details ASIN.
What to buy instead, and what these sheets still do well
For a walking tunnel, buy from a supplier that cuts or calculates the cover for the structure and publishes the film specification and UV term. Provide the hoop measurement, tunnel length, door arrangement and anchoring method rather than asking only for a square-metre total. Compare like with like once you have a required size: one continuous cover, stated gauge, stated UV terms and the necessary fixings. The amazon set remains useful for cold frames, beds and small greenhouses where its dimensions fit.
Once you have a correctly sized tunnel skin, fitting determines whether it rubs or flaps. The polytunnel polythene fitting guide covers still weather, sharp frame points, fixings and tension. Choosing the proper object first makes those steps possible; fitting skill cannot create missing width or a UV warranty.
Common questions
Can a 2 m × 2 m sheet cover a polytunnel?
Not a typical walking tunnel. Two metres is unlikely to span from one fixing edge over the hoop to the other, and the sheet leaves no useful tunnel length. It is better treated as cold-frame, bed-cover or patch material.
How much extra length do the ends need?
Northern advises about 3 m per end for covers fixed to door frames, plus another metre of caution on wider tunnels with doors at both ends. Use the guidance for your frame and supplier rather than applying that allowance blindly to every design.
Is 150 micron enough, or should I choose 180 or 200?
All three appear in named UK horticultural films. The researched examples pair 150 micron with four UV years, 180 micron with five seasons or years, and 200 micron with seven years. Buy the named film’s complete specification and warranty; thickness alone does not determine life.
Is the Pumtus 3 m × 8 m sheet a tunnel cover?
It is sold as greenhouse film and states 6 mil, but the research does not show a UK service term or prove that 3 m spans your hoop. It has only one UK review in the raw file. Measure first and do not treat area as a warranty.
Related pages
Sources
Public UK and manufacturer sources from the research digest, used for this page in October 2026.
- BSI — BS EN 13206:2025 greenhouse and tunnel films (retrieved 17.10.2026)
- Northern Polytunnels — Durathermic clear polythene (retrieved 17.10.2026)
- Premier Polytunnels — polythene films (retrieved 17.10.2026)
- Northern Polytunnels — covering a polytunnel (retrieved 17.10.2026)
- RHS — choosing a greenhouse (retrieved 17.10.2026)
- Consumer Rights Act 2015, section 11 (retrieved 17.10.2026)
- GOV.UK — waste duty of care code of practice (retrieved 17.10.2026)
- SEPA — agricultural waste (retrieved 17.10.2026)