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The initial investment into a polytunnel can be quite significant, it is certainly a wise idea to consider how to keep it in the best shape to maximise its longevity and performance. Maintaining your polytunnel may seem like a daunting task at first but once you get to grips with the key components that make up your polytunnel, you’ll be able to self-refurbish and repair it to keep it working at its best.

Here we break down the key points to inspect and how to remedy any issues.

What is a Polytunnel Polythene Cover?

The Polytunnel Cover is the fabric that covers the frame of the polytunnel. It is usually made from a durable plastic polythene material that is UV-resistant and able to withstand adverse weather conditions. While the polythene cover may not be the most expensive part of your polytunnel, it is one of the most important as it sits at the core of the shelter’s purpose.

Is your polythene showing signs of wear?

Polythene doesn’t last forever and over time can become brittle, discoloured, or torn.

Small tears can happen, it’s easy to inadvertently catch the polythene with a wheelbarrow or fork. Luckily, small cuts can be repaired easily. If the damage to your polythene isn’t caused by a mishap, it’s important to understand the cause so further damage is avoided. Overhanging trees and blowing debris are common causes of damage so make sure trees are cut back and any objects that could blow away are secured. Equally if there is a point in the framework that is rubbing on the film, be sure to remedy this by applying additional hotspot tape to the framework.

How to repair small cuts to your polytunnel cover?

Small cuts are easy to repair with specifically designed UV stabilised polythene repair tape. Repair tape is available in a selection of widths depending on the size of the tear, this tape is highly adhesive and gives maximum light transmission to ensure no performance is lost.

When applying repair tape ensure you have dry weather, clean around the tear – both inside and outside. When applying tape, it is easier with assistance, you will also get better adhesion if someone can support the tape on the opposite side as it is being applied.

To get the best results, stick the tape on both the inside and outside, ensure you have an even amount of tape on each side of the tear, and then extend the tape beyond the tear for at least a couple of inches.

What do I need to replace my polytunnel cover?

First you will need to order sufficient polythene, to do this you will need to measure your tunnel and use our handy polythene calculator to work out how much you require. You may also need to order other replacement parts such as anti-hot spot tape and polythene fixing components (i.e., timber batons, wiggle wire or polythene fixing strips).

Before you jump straight into ordering a replacement cover, ensure to take some time to consider if you want to add any additional elements to your tunnel such as ventilation, ridge poles or crop bars as these can be easily added during the recovering process.

Northern Polytunnel Covers are industry leading

Northern Polytunnels have been at the forefront of polytunnel design and manufacture for over 50 years, so it is no surprise that our polythene covers are industry leading. We use Visqueen Lumisol polythene to cover our polytunnels as it offers superior growing performance and longevity. Lumisol polythene is also produced in the UK specifically for the British market which is important to us as a British manufacturer.

Replacing Polytunnel Doors

Generally, door posts would go rotten where they meet the ground. Again, look for rotten timber or corroded aluminium.

It is also important to check that the screws in the door hinge are still secure, if not these should be replaced with a larger screw or countersunk bolt. Likewise, if it’s a sliding door track, ensure the screws fixing this are secure, if not remedy in the same way as described above for the hinges.

Replacing Polytunnel Base Rails

We have been manufacturing polytunnels for over 50 years and have seen first-hand how critical long-lasting and resilient base rails are for extending the life of your polytunnel. All our base rails are either made from treated timber or high-quality aluminium to ensure you get the maximum from your polytunnels base rails.

What type of polytunnel base rail do I have?

The base rail is the connection between the polythene and the foundation, depending on what kind of base rails you have will determine what you need to look for.


This means you will have no physical base rail and have instead opted to bury the polythene into the earth. If this is the case, you need to check that the earth hasn’t been washed out and is still providing adequate and even tension on the polythene. If you find that this isn’t the case, simply add more earth to ensure a good hold.

Treated Timber

If your polytunnel has wooden base rails it is important to check for rot in the wood where it connects to the foundations and that the nailed-on batons are still firmly held. Whilst checking the condition of the timber it is important to check the bolts holding the timber to the foundations are tight. If the timber is showing signs of decay, then it is important to replace these before recovering your polytunnel. If the decay is very bad and the timber has softened, it might be time to replace the base rails and cover now to avoid losing your cover and ensure your crop is protected.


If you have aluminium base rails on your polytunnel these should only need checking for corrosion if the tunnel is over 15 years old. It is normal for aluminium to go slightly white as this is the natural oxidation that creates a protective barrier. Corrosion will be evident if the metal has started flaking. Whilst you are inspecting the base rails check that the polythene fixing system employed on your tunnel is still fitted correctly and holding the polythene tight.

Polytunnel Foundations

Irrespective of material, anything that is sunken into the ground can corrode. A quick inspection can check for heavy corrosion or flaking of metal. Concrete can also decay over time and become flaky and begin to break up. Should any of this be the case, it is important to remedy with new foundations to prevent potential damage to the rest of your tunnel.Polytunnel Nuts and Bolts

Ensure everything is still tight and none of the bracing has slipped. You could use a spirit level to check that the gable ends are still vertical and rectify if they are not. Although simple, doing this often can easily circumvent possible issues.

If you follow all the points above, you should be able to extend the lifespan of your polytunnel and enjoy many successful growing seasons. However should you need any support or guidance on how to maintain your Polytunnel don’t hesitate to reach out to one of our industry experts who will be more than happy