A recent online discussion sparked an interesting question: When it comes to the structure of a polytunnel, is timber still a smart choice?
While timber-framed tunnels are still widely available in the UK, more and more growers are questioning their longevity, especially in the face of rot, warping, and general wear from constant exposure to moisture and temperature shifts. Several experienced voices chimed in to share their real-world experiences, and the consensus was clear: even pressure-treated wood doesn’t always hold up as well as people expect.
In contrast, galvanised steel polytunnel frames are proving far more durable, more stable, and ultimately more cost-effective over time.
The Problem with Timber in Polytunnels
Some sources claim that pressure-treated timber can last up to 30 years. In theory, under ideal conditions, this might be achievable. But when timber is used in growing environments with constant moisture, temperature swings, and direct contact with soil, the actual lifespan is often far shorter.
One experienced grower recalled dismantling a tunnel just three years after installation. The timber door posts had already rotted in the ground, and much of the frame was warped or starting to decay. The only viable fix? Rebuilding the entire end frame and recovering the tunnel.
Others pointed out that while timber treatments have improved in safety, they have reduced effectiveness. Modern pressure-treated softwood can begin to fail after just a few years unless you use incised timber with more aggressive treatment; even then, longevity can be unpredictable.
Why timber often falls short:
- Contact with damp soil encourages rapid rot, even in treated timber
- Humidity and temperature fluctuations inside tunnels cause warping and cracking
- Once the timber fails, replacing structural elements becomes complex and expensive
- Cutting treated timber exposes untreated inner grain, reducing protection
Why Galvanised Steel is a Smarter Choice
Galvanised steel has become the framing material of choice for many serious growers, and for good reason. It doesn’t rot, warp, or split. A properly hot-dipped galvanised frame will last for decades with minimal maintenance.
Even better, steel provides a strong and consistent base for cover tensioning, door alignment, and ventilation features. It’s also fully recyclable and won’t require staining, painting, or chemical treatment.
Key benefits of steel-framed polytunnels:
- No timber means no risk of rot or moisture damage
- Long-lasting and low-maintenance
- More stable for doors, covers, and accessories
- Easier to upgrade or re-cover in future
- Proven performance across a wide range of growing conditions
We designed the EasyBuild Polytunnel to offer all these advantages with no compromise. It uses heavy-duty oval steel tubes, a fully galvanised structure, and no timber anywhere in the build, making it the toughest tunnel on the market.
Polytunnel Repairs and Refurbishments: Fixing Common Issues
If you’re working with an older tunnel that has timber parts, you don’t need to start from scratch. Many common issues can be fixed with the right products and a bit of DIY.
Here’s how to tackle the most frequent polytunnel problems:
- Small tears in your polythene cover? Try our Polythene Repair Tape for a fast and weatherproof patch.
- Is the cover too far gone? You can order replacement polytunnel plastic cut to size.
- Need help re-covering your tunnel? Watch our step-by-step covering guide video.
- Missing or broken structural parts? Visit our parts and accessories shop for spares and upgrade kits.
Final Word: Is Timber Worth the Trade-Off?
Timber-framed polytunnels may look appealing on paper, but they can quickly become a source of maintenance headaches. Even pressure-treated wood can rot, warp, or fail after just a few years in typical UK growing conditions.
On the other hand, a steel-framed tunnel like the EasyBuild offers long-term peace of mind with a lower total cost of ownership. You won’t need to rebuild door frames, replace base rails, or fight with cover tension year after year.
Sometimes, investing in strength from the start saves more than just money; it saves time, hassle, and a whole lot of frustration down the line.
