Replace your polytunnel cover or change to a greenhouse?
The next split in a polytunnel cover can begin where the film touches the frame. Heat and friction at that contact deserve checking before you buy another sheet; Premier Polytunnels recommends protective tape on the hoops for those reasons. If you need to replace a polytunnel cover, inspect what lies underneath first. Then compare a patch, a new sheet and a complete greenhouse on the same area of ground.
- Patch local damage. Inspect the area around a tear before choosing tape. Check that the frame is still sound.
- Re-cover a sound tunnel. Film preserves the frame you already own and leaves much less to buy.
- Change systems for a reason. Polycarbonate removes film re-covering from the routine, while keeping other maintenance and replacement costs.
Should you replace a polytunnel cover or buy a greenhouse?
Repair a local tear if the surrounding film can hold a patch. Re-cover when the frame remains usable and the whole sheet needs replacing. Consider a greenhouse when you want a different covering system and can justify the complete purchase. Start with the frame inspection, then compare the same floor area and all remaining work.
Check the hoops and their joints, the door frame and the anchoring points. Find where each tear began. A split against a fitting calls for a different remedy from an isolated puncture in otherwise intact film. If the structure has moved or distorted, ask its maker what needs repairing before stretching new film over it.
Premier’s covering instructions recommend anti-hotspot tape on hoops to protect against friction and heat at the frame. That is separate from the clear tape used to patch a tear. Follow the instructions for your tunnel and covering; a new sheet cannot correct an unresolved frame defect.
What are you comparing on 18 m²?
Use a 3 × 6 m tunnel as the reference floor area. A 6 m Plot 3.14 also gives 18 m² on the ground. Film for that tunnel must cover its curved roof as well as the ends, with allowances for fixing, so its purchase area is much larger than the floor.
The table assumes you already own the tunnel frame. Replacing its cover therefore buys a covering, while changing to Plot buys a new frame as well.
| Route | Published purchase or worked calculation | Work and costs still to allow for |
|---|---|---|
| Patch an existing cover | Rhino temporary repair tape, 50 mm × 10 m: £2.99 including VAT, before delivery | Inspect the damage and patch it yourself, following the tape maker’s instructions; further materials if the damage needs them |
| Re-cover the existing tunnel | Conditional SunMaster Diffused order, 7.3 × 12 m: £127.82 including calculated VAT plus cutting and standard mainland delivery | Frame repairs and fitting materials; your own labour or a separate quote |
| Replace with Plot 3.14, 6 m | £1,099 for 4 mm twin-wall polycarbonate and 1.00 m arch spacing | Old structure removal, site preparation and assembly; any postcode surcharge or optional extras |
Tape delivery and the film despatch date were not confirmed. Get a final delivered quote. Neither figure includes paid fitting.
When is tape enough?
When the damage is confined to a repairable area and the surrounding film remains sound enough to hold the patch. Check the cause, then follow the repair tape and cover maker’s instructions.
Fosseway describes its £2.99 Rhino roll as temporary repair tape. Premier’s repair guidance advises mending a tear as soon as you spot it, with tape made for polytunnels. Use a product compatible with your film, follow its instructions and inspect the repair afterwards.
If tears are spreading across the sheet or each patch needs another patch beside it, ask the cover supplier whether the film is still repairable. Tape cannot restore a damaged hoop or anchor. Keep the cost of any structural work separate from the roll in your basket.
How much polythene do you need?
Measure over a hoop and add the allowances for your fixing method. Work out the length needed for the roof and ends separately. Send those measurements to the supplier before ordering a cut sheet.
Direct Polytunnels’ measuring guidance adds the roof length to twice the height, then adds end allowances. For base rails it gives 0.6–1 m extra at each end. Trench fixing needs its own allowance.
For illustration, a 6 m long, 2 m high tunnel with 0.6 m allowances gives 6 + 4 + 1.2 = 11.2 m. A 12 m order would cover that calculated length. Separately measure the hoop arc and side allowances to establish whether a 7.3 m roll is wide enough. Floor width alone cannot answer that question.
That conditional order contains 87.6 m² of film. XL Horticulture lists 7.3 m SunMaster Diffused at £7.21 per running metre excluding VAT. Twelve metres comes to £86.52. Add its published £10 cutting charge for 11–19 m and £10 standard mainland carriage, then 20% VAT: £127.82 after rounding. Confirm the tariff, film thickness and lead time before buying, as these were not all stated on the price page.
What does a lifespan claim actually tell you?
Use the statement for the exact product you are buying, with its conditions. A manufacturer’s UV guarantee and an expected service life answer different questions; neither gives a replacement date for your particular tunnel.
XL Horticulture lists a 5-year UV guaranteed life and an 8+ year life expectancy for SunMaster Diffused. Those are the manufacturer’s claims. Ask what the guarantee covers and which installation and care conditions apply. Keep the product identity and invoice so a future claim can be checked against the relevant terms.
A well-kept film tunnel can remain the sensible choice. Replacing sound hoops simply to avoid buying another cover would need a reason beyond the film price shown here.
What changes with screw-fixed polycarbonate?
Plot replaces the tunnel with a galvanised steel frame and twin-wall sheets fixed by screws and washers. There is no film to re-cover. The panels still age, and anchoring and sheet fixings need checking, as do the edge tapes.
The 6 m Plot 3.14 was £1,099 in the base configuration on 20 October 2026: 4 mm sheets and 1.00 m arch spacing. It is 3.00 m wide on the ground and 3.14 m at its widest. Two doors, one at each end, have upper sections that open independently. Roof vents with automatic openers are optional.
“Engineered for British storm conditions” describes a construction with 40 × 20 mm closed steel profile, galvanised with a ZAM coating, and screw-fixed panels. It gives no tested wind-speed rating. Anchoring and installation remain essential, and this comparison promises no polycarbonate service life or immunity from damage.
Walk round Plot once a year to check that anchors remain firm, screws snug and tapes sealed, as its warranty asks. For other differences in use, see our polytunnel and polycarbonate greenhouse comparison. Our polycarbonate polytunnel guide explains that covering system in more detail.
What should a labour quote include?
List removal, disposal, ground work and fitting separately. If doing the work yourself, use the same list to plan the people and weather window you need.
- Inspect and photograph the existing structure and its fixings, including the points where the covering failed.
- Confirm whether the structure can be reused and obtain prices for required repairs.
- Measure the covering to the supplier’s method, or check the new greenhouse base plan.
- Price materials and delivery, then obtain a separate labour quote if needed.
- Plan old-cover removal and disposal before starting the replacement.
Plot needs a base 3.2 m wide and 6.25 m long for the 6 m model, with 2 m clear of fences and buildings on every side, as the manual asks. An existing 3 × 6 m tunnel footprint alone cannot prove it will fit. Check the full site through our base preparation guide.
When should you keep the film tunnel?
Price a compatible replacement cover first. The worked film order costs far less initially than a complete new greenhouse, and preserves the structure already on site.
Film remains worth considering for the lower initial spend and flexibility of covering a large frame. Compare the size you need, without shrinking the growing area to make another system fit the budget.
Consider Plot if its dimensions fit and its complete cost is justified. There is no film to re-cover, but inspection and eventual repairs remain part of ownership.
Measure for the 6 m Plot
Compare the 18 m² floor with your present tunnel, then check the 3.2 × 6.25 m base plan and clearances before ordering.
What we checked for this guide
Film prices and lifespan statements come from named suppliers. Worked sheet quantities are conditional on measuring the existing tunnel. No polycarbonate lifespan is promised. Checked 20 October 2026.
- 01Premier PolytunnelsHow and when to cover a polytunnel
- 02Fosseway TapesRhino clear repair tape, 50 mm × 10 m
- 03XL HorticultureSunMaster Diffused polythene
- 04Premier PolytunnelsHow to repair your polytunnel
- 05Direct PolytunnelsPolythene replacement cover, 7.3 m: how to measure
Related guides
Written by the Waldenhaus team. We sell outdoor saunas and greenhouses and write these guides from manufacturer manuals, official guidance and our own product pages. Where your equipment manual says something different, follow the manual.