Replacing polytunnel covers on commercial polytunnels?
- polytunnelsrusweb
- 14 hours ago
- 3 min read
Are all polytunnel covers of the same quality?
No. Polytunnel covers can look similar, but grade, thickness, UV resistance and installation quality matter once they are stretched over commercial polytunnels. Cheap film may cover the frame quickly, then split early, go brittle, or sag after a rough spell of weather.
For commercial polytunnels, we would recommend a professional-grade polythene with a proven UV life. A straight question works here: which polytunnel covers are you fitting, who made the sheet, and will it suit a heated or damp growing house?
What type of polythene is best after heat and heavy rain damage?
Choose polytunnel covers with strong UV stability, tensile strength and enough flexibility for movement. Severe heat can make polythene film brittle. Heavy rain then finds every weak point, especially around doors, crop bars, base rails and folds.
Many commercial polytunnels use clear polythene for maximum light, but there are different finishes. Thermal film can help hold warmth. Anti-drip stops a lot of roof sweat from landing on the crops. For commercial polytunnels with scorch patches, diffused film gives the light a softer spread instead of hard, bright bands.
How thick should replacement polytunnel covers be?
Replacement polythene is chosen by strength and lifespan, not thickness alone. A thicker film is not automatically better if the UV treatment is poor or the sheet has been stored badly.
Your installer should explain the micron gauge, service life and warranty terms. If they cannot, be wary. Commercial polytunnels need covers specified for site conditions, not the cheapest roll available.
Does installation matter as much as the polythene cover?
Yes. Even good polytunnel covers can fail early if they are fitted loosely, dragged over sharp edges, overheated during fitting, or fixed without enough attention to wind load. Tension matters. So does timing. A polythene cover fitted on the wrong day can become too tight in cold weather or too slack when temperatures rise.
An experienced installer will check the frame before fitting. On older commercial polytunnels, they should look for rough hoops, worn rails, missing anti-hot spot tape, damaged timber and poor door detailing. Small faults can wreck new polythene faster than people expect.
Should you replace covers on several tunnels at once?
If several structures have been damaged, replacing the worst sheets first may be sensible, but it is worth having every frame assessed. The same type of weather event can weaken the polythene that has not fully failed yet.
There is a practical advantage, too. Ordering several bays together can reduce downtime and keep the polythene specification consistent across the site. It also helps the installer plan the installation.
What should you ask a polytunnel installer?
Ask these questions before you book the work:
What grade of polythene are you fitting?
What UV life and warranty does it carry?
Is anti-drip, thermal or diffused film better for our crop?
Will you inspect the frame and replace the anti-hot spot tape?
How will you tension the film and handle vents, doors and base rails?
Have you fitted covers on commercial polytunnels of this size before?
The short answer is simple: polytunnel covers are not all the same. For commercial polytunnels, choose polythene around the crop, site, weather exposure and fitting standard. A better cover fitted properly is usually cheaper than doing the job twice.
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