18ft Wide Polytunnels

Is it time to scale up to commercial production? Are you expanding your efforts to grow your own? Increasing the size of your smallholding or small farm venture? An 18ft wide polytunnel could be just what you require to take your sowing and growing to the next level. The 18ft wide polytunnel is a good size for a commercial polytunnel, though it could also be a large domestic one. Whatever use you have in mind for your 18ft wide polytunnels, we are here to make sure you get exactly the right polytunnel for you. To learn more about what is included in your purchase of an 18ft wide polytunnel, check out 'What's In The Kit'.

Next, all you have to do is select the length of your tunnel and make choices about what exactly you require. Before making your purchase, you should also check out all the extras that could be purchased at the same time and could make your life a lot easier. Base rails, crop bars, sliding doors and staging, for example, can all help in a number of ways. Even better, when you add extras or accessories our bonus save deal means that you will make better and better savings on your polytunnel purchase!

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Intro

All Our Prices Include VAT FREE Delivery 14 Day Money Back Guarantee

Tech Specs

This is the most popular of our Commercial Polytunnels. It's also one of the strongest Polytunnels around, thanks to 50.8mm diameter E370 high tensile pre-galvanised steel tubing with 6ft (1.83m) hoop spacing. It also has great design features, like the straight 3ft 3in (0.99m) sides that give really good clearance for a highly versatile growing area, and a good return on the economical floorspace.

Technical Specification

Width 18ft (5.49m)
Hoop Spacing 6ft (1.83m)
Overall Height 8ft 6in (2.59m)
Straight Side 3ft 3in (0.99m)
Head Room (15cm from side) 5ft (1.52m)
Hoop Diameter 2in (50.8mm)
Steel Specification E370 Galv High Tensile
Door Opening Width 7ft 6in (2.29m)
Door Opening Height 7ft (2.13m)
Distance over Hoop 28ft 7in (8.76m)
Door Frame 4in x 2in (100mm x 47mm)
Inner Door 3in x 2in (75mm x 47mm)
Base Rail 3in x 2in (75mm x 47mm)

Instructions

We have two construction guides for our 18ft Wide Polytunnel Model.

18TR for polytunnels who require the cover to be buried in a trench.  18BR for polytunnels that have Base Rails eliminating the requirement for digging a trench

If you are experiencing problems with your polytunnel construction, our construction team are available to answer your questions and help in whatever way they can. Simply call 01282 601253 on week days between 9am-5pm...PLUS weekend cover on 07801 601253, between 9am-5pm or contact us. Alternatively, you can visit our construction resources website at construct.firsttunnels.co.uk.

We haven’t stopped there, we know many people build their polytunnels at the weekend or over a bank holiday when our office is closed, so we have also produced  a series of Polytunnel Construction Videos. This collection of videos can be viewed anytime, on your home computer, and even your phone for when you are in the thick of things constructing your polytunnel.

Thomas Cockbill
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Verified order

Great helpline and well constructed

Stewart Harrison
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Verified order

Excellent product.

Patrick Mac.
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Verified order

Seems very good. It's being shipped to Tanzania so I await feed back.

Alan Edgington
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Verified order

The framework was one that I acquired from a client who had been in market gardening. I built it about 15 years earlier relying on a plan and some photographs and I thought I had made a good job of it. After it was wrecked in storms a few years ago I almost gave up but the enjoyment that comes from such a structure/facility was sadly missed. First Tunnels team and materials have brought it all back to life and it's use is now in full flow

World of Hedges
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Verified order

product good, twisted timber base rails not good

andrew sanderson
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Verified order

I bought an 18 x 30ft tunnel and was pleasantly surprised with the quality of the frame - its heavy duty stuff !. The instructions are easy to follow and, unlike most instruction manuals, I would urge anyone installing a tunnel to read twice to get a good idea of the install process. Most queries are answered in the QR linked videos - any remaining queries are answered via phone. I expected to have the tunnel built in two days but it took 7 days for two of us to complete. The process is simple but allow time to get it right. Anyone with basic DIY skills can install - anyone who isn't so good with DIY I would look at First completing the install. Now that the tunnel is complete, the structure is rock solid and looking great. Really pleased with the end result.

Jenny
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Verified order

Excellent , already using it , it is very robust construction.

Susan Atkins
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Verified order

Amazing quality, super strong, who needs to worry about wind and rain when you have a Polytunnel.

Paul Bishop
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Verified order

Well made and good instructions Arrived on time

What's In The Kit

We supply Timber Hinged Doors at each end, Anti Hot Spot Tape, Timber Base Rails and of course the Framework to support our 200 micron Super Therm Polythene cover. These options are pre-selected below, but can be amended to suit your needs.

You will be required to secure the foundations into concrete, alternative methods of securing the polytunnel can be selected, eliminating the requirement of concrete – see ‘Polytunnel Foundation’ section.

Options & Prices

Select the options below in order to configure your Polytunnel and when you’re happy, press "Add to basket"

Select Length

Select Type Of Cover

Help Me Choose

Your first big decision when choosing a Polytunnel is almost always..."What size is ideal?". But there's other important factors to take into consideration..."What type of cover do I want?". It might not sound like something to give a lot of thought to, but the cover you choose will affect your day-to-day Polytunnel management, what and how you grow. We have 4 options to choose from...

Super Therm

Our most popular polythene cover incorporates an additive that increases its Thermic efficiency, yet still retains 90% light transmission. In simple terms the polythene helps trap and preserve higher temperatures inside the structures for much longer - in heated structures, a 15-20% fuel savings can be achieved. A beneficial side effect of this added additive is that light entering the polytunnel is diffused - scattering light evenly throughout the structure. This UV stabilised film is 200 microns (800 Gauge) and is supplied with a five year guarantee.

FOR USE WITH All crops where heat is important such as bedding/annual plants, propagation houses & over wintered vegetable production.

Properties

Supplier

Our polythene is exclusively sourced from Sotrafa in Spain, the world's biggest producer of horticultural film with an enviable reputation for quality thanks to exhaustive testing in the demanding weather conditions of Almeria.

First Tunnels are the sole distributor of Sotrafa products in the UK, and we are proud to work with the global leader to deliver the best possible products for our customers. UK suppliers make cheaper alternatives, but the quality simply doesn't compare.

Warranty

Although guaranteed for 7 years against its biggest threat of sunlight degradation, when fitted correctly, it is not uncommon to hear our polythene covers have lasted in excess of 10 years.

View the terms of the Guarantee here.

Polythene Guarantee
UV Filters
Solar Radiation

Sunlight is the biggest enemy of polythene. While it's essential for the wellbeing of whatever you're growing, it also 'kills' polythene in much the same way you can find old discarded crisp packets lose their colour and become very brittle. First Tunnels polythene covers are developed and tested in the extreme conditions to give optimum performance and are UV stabilised to prevent the polythene from breaking down prematurely.

What is a KLy?

A Kilo-Langley is the measure of Solar energy radiated in 1 year. It varies from a minimum of 60 KLy in the Polar regions to 120 KLy in warm regions, and to a maximum of 200 KLy in the African desert. Southern Spain receives about 140 KLy whereas the UK receives about half of that, just 78KLy.

Thickness
Thickness

Our Super Therm polythene is 800 gauge/200 micron and made up of 3 layers for outstanding strength and performance.

We use a 3 layer polythene made of exceptional quality material, which has a hugely beneficial thermal effect.

The common misconception about polythene is the more layers, the better the product. Unfortunately this isn't true. More layers simply hide poor quality films, which are sandwiched inside a very average inner and outer skin. The result of these multi-layer (often called 5 or 6 layer) films is a noticeably poorer all-round performance - the thermal effect is significantly decreased.

Optical Properties
Total Transmission of Visible Light

Total Transmission of Visible Light
The amount of available light entering the polytunnel through the film. Measured as a percentage of total light.
Super Therm = 95%

Diffusion

Diffusion
The scattering of direct light entering the polytunnel ensuring no shadows, so all plants receive equal light. Measured as a percentage of total light.
Super Therm = 30%

Thermal Effect

Thermal Effect
A pocket of additives within the layers of the film that ensure and maintain a stable and optimum temperature within the polytunnel, especially during the night when it is colder.
Super Therm = 85%

Mechanical Properties
Strength at Break

Strength at Break
The load on a tested sample when it breaks. This is expressed in Pascals or MPa.
Super Therm = MD24/TD23

Elongation at Break

Elongation at Break
The strain on a tested sample when it stretches. This is also expressed in Pascals or MPa.
Super Therm = MD920/TD920

Creep

Creep
As the weather changes becoming hotter or colder, so the Polythene expands and contracts. Creep is the terms used to express this.
Super Therm = 5

Dart Test

Dart Test
A test to measure the impact strength on a test piece of plastic, using a weighted falling 'dart'.
Super Therm = 450

Smart White

This specialist film reduces light transmission to 65%, and ultimately the temperature inside the structure. This film is most useful where sun scorch is a problem for growers. It is also suitable for animal husbandry applications and other stock and storage houses where a great build up of heat is not ideal. This UV stabilised film is 180 microns (720 Gauge) and is supplied with a five year guarantee.

FOR USE WITH Animal Husbandry structures and those plants that would normally grow under a shade canopy.

Properties

Supplier

bpi.visqueen is a division of British Polythene Industries plc - one of Europe's leading manufacturers of polythene film products. Their products are used by Farmers, vegetable, fruit and flower growers across the globe and are all designed to help the grower create their own 'climate for success'.

Warranty

Although guaranteed for 5 years against its biggest threat of sunlight degradation, when fitted correctly, it is not uncommon to hear our polythene covers have lasted in excess of 10 years.

View the terms of the Guarantee here.

Polythene Guarantee
UV Filters
Solar Radiation

Sunlight is the biggest enemy of polythene. While it's essential for the wellbeing of whatever you're growing, it also 'kills' polythene in much the same way you can find old discarded crisp packets lose their colour and become very brittle. First Tunnels polythene covers are developed and tested in the extreme conditions to give optimum performance and are UV stabilised to prevent the polythene from breaking down prematurely.

What is a KLy?

A Kilo-Langley is the measure of Solar energy radiated in 1 year. It varies from a minimum of 60 KLy in the Polar regions to 120 KLy in warm regions, and to a maximum of 200 KLy in the African desert. Southern Spain receives about 140 KLy whereas the UK receives about half of that, just 78KLy.

Thickness
Thickness

Our Smart White polythene is 720 gauge/180 micron and made up of 3 layers for outstanding strength and performance.

Optical Properties
Total Transmission of Visible Light

Total Transmission of Visible Light
The amount of available light entering the polytunnel through the film. Measured as a percentage of total light.
Smart White = 65%

Diffusion

Diffusion
The scattering of direct light entering the polytunnel ensuring no shadows, so all plants receive equal light. Measured as a percentage of total light.
Smart White = N/A

Thermal Effect

Thermal Effect
A pocket of additives within the layers of the film that ensure and maintain a stable and optimum temperature within the polytunnel, especially during the night when it is colder.
Smart White = N/A

Mechanical Properties
Strength at Break

Strength at Break
The load on a tested sample when it breaks. This is expressed in Pascals or MPa.
Smart White = MD23/TD22

Elongation at Break

Elongation at Break
The strain on a tested sample when it stretches. This is also expressed in Pascals or MPa.
Smart White = MD630/TD770

Creep

Creep
As the weather changes becoming hotter or colder, so the Polythene expands and contracts. Creep is the terms used to express this.
Smart White = 5

Dart Test

Dart Test
A test to measure the impact strength on a test piece of plastic, using a weighted falling 'dart'.
Smart White = 700

Net

This green net incorporates durable flat tape threads and double lockstitch tearproof technology and is used as a windbreak or shade product to protect those hardier and specialists plants. This net has proven its durability in the toughest of conditions and also provides excellent protection against insect and birds. 50% density.

Properties

Supplier

Tildenet is now considered to be one of the major brands of netting and textile manufacturers in the world. Exporting to over 100 countries, providing an extensive range of products for markets such as construction, sport and horticulture. Tildernet supply and manufacture extruded nets and meshes for all kinds of applications.

Warranty

Although guaranteed for 5 years against its biggest threat of sunlight degradation, when fitted correctly, it is not uncommon to hear our net covers have lasted in excess of 10 years.

View the terms of the Guarantee here.

Polythene Guarantee

Polytunnel Foundation

Help Me Choose

We have four options available. Foundation Tubes can be driven into the ground (if the polythene is to be trenched) alternatively you can use Anchor Plates. If you have a solid base of concrete or timber then Base Plates will be required.

More Info

Cover Fixing

Help Me Choose

We have three options available. The Trench method requires a trench digging all around the perimeter of the tunnel approx. 30cm wide and no less than 40cm deep. Quicker and easier than trenching the cover, are Base Rails, which are available in Timber or Aluminium versions.

More Info

Belts & Braces

Help Me Choose

We have two options available. Crop Bars are attached to every hoop apart from the first and last, Twin Support Brace runs down the full length of the tunnel, either side of the central ridge, both are ideal for hanging baskets, suspending canes/nets & crops.

More Info

Ventilation

Left

Right

Help Me Choose

We have three options available. Side Ventilation is a fixed rail (Timber or Aluminium) underneath which, is fixed a net windbreak, allowing ventilation and air flow. In addition we also have Timber Side Ventilation & Screen, which allows the net to be covered through the use of a screen, which can be lowered/raised, helping control temperature and air flow. Please note, the Screen is not compatible with Aluminium. All options available, for one or both sides.

More Info

Useful Extras

Help Me Choose

Ground Cover inhibits the growth of annoying weeds. Acting as an excellent sub-base for use with bark, mulch or gravel. Ground Cover provides total floor coverage, supplied with metal staples.

Staging introduces a work surface at the ideal height of 75cm, significantly adding growing space. Complete with brackets, allowing you to attach a worktop (not supplied) of your choice. 

Polythene Care Kit contains 1 roll of 2 inch, 3 inch and 4 inch repair tape and a 20 litre container of Algon Organic.

Useful Extas
More Info

Irrigation

Help Me Choose

Overhead Irrigation incorporates a twin spray line suspended to either side of the central ridge. Supplied with a header pipe, down tubes, sprinklers, inline tap, filter and hose connector. This complete kit is ready to go, just connect a hose and you’ll be amazed how quickly it will pay for itself in terms of time, money and improved productivity.

Automatic Overhead Irrigation is supplied with the added advantage of a weather resistant, battery operated hose end water timer. Essential for those days when you just can’t be there to operate the system manually.

Irrigation
More Info

Polytunnel Door Options

Front

Rear

I want to design and build my own doors

Help Me Choose

All Polytunnels supplied come complete with two doors. We have hinged and sliding door options...

Hinged Doors

All door panels are covered with polythene, ventilation is easily controlled as you can leave any gap of your choice with our 'Unique' ground bolt locking system.

The Outer Door Frame is 100mm x 50mm, whereas the Inner Door is 75mm x 47mm. All timber used is FSC® certified.

Door Options
No Door Option

We also offer a DIY option...make your own doors and end frames. If you prefer to build your own bespoke doors  - you can exclude the doors and timber end frames and receive a discount.

Sliding Doors

All door panels are covered with polythene, ventilation is easily controlled as you can slide the doors open to leave any gap of your choice. Sliding doors sit securely on the doorframe, flush to the polytunnel, and out of harm's way.

The Outer Door Frame is 75mm x 47mm, whereas the Inner Door is 50mm x 50mm. All timber used is FSC® certified.

Door Options
No Door Option

We also offer a DIY option...make your own doors and end frames. If you prefer to build your own bespoke doors  - you can exclude the doors and timber end frames and receive a discount.

Freebies

Help Me Choose

When you buy one of our Polytunnels you will receive a Free Polytunnel Lucky Bag, consisting of the following:

The two best selling Polytunnel books by Andy McKee and Mark Gatter.

Crop wheel, a wealth of growing information...when to sow, grow, harvest and a really useful measuring device too.

Polytunnel planner, the essential monthly planner packed full of tips and advice.

Tomato seeds, specially selected to help you get your polytunnel growing...they taste yummy too.

Polytunnel Growing Guide, will take you through a whole 12 months of activity in your polytunnel.

Free Gifts