Our original Commercial Timber Range of polytunnels offer an economical option over the Commercial Aluminium Range.
This is the traditional method of building polytunnels, with the polythene being fixed with timber battens nailed onto the timber door frames and side or base rails, it’s simple and cost-effective.
Our commercial range of structures use the most suitable materials possible, our timber is graded using C16 and C24 grades and our steel is ArmourGuard zinc magnesium coated. We manufacture all our fittings in house which are strength tested and protective coated.
The foundation tubes use are a substantial 2.5mm wall thickness that pairs with a cover tensioning system that allows you to tension the cover after it’s been fitted ensuring a drum-tight finish.
Our in-house engineers have calculated the wind and snow loads to ensure that every polytunnel we manufacture can withstand the weather at your location.
Our commercial polytunnels are renowned for their strength which is why you can expect to see them in the most hostile environments, from the Shetlands to The Falklands.
Why Choose Us
Gallery
Strength
Single Span Features
Options
Sizes / Instructions
Not all polytunnels are built the same
With over 50 years of experience designing and manufacturing polytunnels, we know that quality counts, that’s why we build our polytunnels to last. If you are comparing us on price against a competitor, you must look at the detail of what you are actually buying, here are some tips on what to look for:
Our 4-piece hoop is made up of a 2-piece arch connected to a straight leg. The leg connection is located on a vertical plane meaning the hoops can withstand a heavier load. Manufacturing a hoop in this way also makes the hoop more customisable by giving the customer the ability to increase the height of the straight leg without compromising the stability of the single span.
Other manufacturers of Polytunnels often have their connections on the curve of the hoop which compromises strength and allows the hoop to ‘snake’. To combat this, extra bracing brackets are used resulting in increased materials, labour and cost.
Aluminium is free from defects that wood has (knots, splits and bows) and will last a lifetime. All our aluminium profiles incorporate our unique ‘W-Wire’ polythene securing system. By simply weaving the ‘W-Wire’ into the open channel of the aluminium rails & frames the polythene is securely trapped in to place. ‘W-Wire’ is the easiest and quickest system on the market and doesn’t require any specialist
tools.
Our timber is fully tanalised to reduce the speed of rotting.
Internal Single Span with Wooden Side and Base Rails
External Single Span with Wooden Side Netted Vent
Wooden 18ft Wide Single Span
High Sided Single Span
Greenhouse Wind and Snow load performance
We strive to give our customers the best product. For this reason, we
undertook the huge task of analysing the strength of our polytunnels.
This is done creating a computer-generated model of the structure
and applying loads from the relevant standards shown in the table
opposite.
These loads are applied to the model of the greenhouse using our
structural analysis software. The software helps us to locate potential
weak spots so that we can optimise our design.
Check If The Polytunnel Suits Your Location
The table below shows the wind and snow load numbers, the higher the number
the stronger the greenhouse required.
Using the maps, pinpoint where your structure is to be
sited; note the colour and zone. Each zone relates to snow loading
and wind speed throughout the country. Check the polytunnel wind
and snow load performance table to make sure the polytunnel will
perform in the area you have pinpointed.
If you need further help with this, please don’t hesitate to get in touch
with our sales team.
(Please note these snow and wind loadings do not apply to our Budget Competitor Range of structures
These Calculation Are Based On The Following Standards
1 Drawings by N P Structures Ltd.
2 EN 1993-1-1:2005, General rules and rules for buildings
3 BS EN 1991-1-3:2003+A1:2015, UK NA General actions – Snow loads
4 BS EN 1991-1-4:2005+A1:2010, UK NA – General actions – Wind actions
5 EN 13031-1:2001, Commercial production greenhouses
Our Single Span Polytunnel Features
The strength of our brackets and fittings have been proven for over 40 years and have been specially designed and manufactured in-house.
Bespoke fittings are designed to simplify the construction process, thereby reducing the construction cost.
ArmourGuard® is NP Structure’s developed high-endurance galvanising treatment, giving extraordinary levels of corrosion resistance. ArmourGuard® offers up to 20 times the corrosion resistance of traditional zinc galvanising due to the combination of zinc, aluminium and magnesium.
Different crops and growing systems require different solutions, which is why we offer a range of options to suit your individual requirements and budget. Options include; doors & louvres - foundations - brace and crop bars - choice of polythene covers - ventilation systems
and irrigation.
Visqueen’s British made polythene allows UVB to enter the greenhouse unlike normal glasshouse films and glass. This has many benefits including enhancing the fragrance, taste, colour of crops with the added advantage of earlier harvesting and longer post-harvest shelf life. It also has a unique condensation reduction additive to further reduce light-loss.
Our polythene is guaranteed for 7 years*
*incremental guarantee from invoice date
Our ground tubes (Foundation Tubes) are 1m long, they are ArmourGuard galvanised treated with a 2.5mm wall thickness.
The image shows a ground tube concreted in with a retaining bar to hold it securely
All of our foundation options incorporate our unique polythene cover tensioning system. The collar tensioning system enables quick and easy tensioning of the polytunnel cover.
The hoops sleeve over the foundation tubes allowing each hoop to be raised individually and locked into position after the polythene sheet has been attached. This stretches the polythene cover to create a drum-tight like cover finish. Unlike some competitors, our system allows easy tightening and slackening throughout the lifespan of the polytunnel
Our Single Span Polytunnel Options
Polythene film: Diffused or Clear?
Light Transmission
Light transmission is the quantity of light going through the polythene, measured by %.
For temperate climates, a rate of higher than 85% is the target.
Thermal Efficiency
Where the heat in the tunnel is retained during the night.
This is measured by thermal retention + thermal transmission = 100 and is expressed as %.
The higher the thermal efficiency, the better the polythene retains heat.
The higher the thermal transmission the more energy is lost.
Anti-Drip
The anti-drip coating reduces condensation droplets and produces more of a film of water.
Benefits of Anti-Drip
Reduces the risk of droplets then dripping which can cause fungal diseases.
Improves the quality of light for photosynthesis, Droplets of water cause light refraction reducing the quality of light.
Note: requires adequate management of the internal micro-climate through ventilation.
Lumisol Clear - Clear Polythene
The clear polythene improves the passage of light into the tunnel to promote photosynthesis.
Clear polythene is measured by haze. The lower the % the clearer the polythene appears and the more light is allowed to be transmitted.
Our clear polythene has 30-35% haze.
Our clear polythene has 88-92% light transmission.
Our clear polythene has 80-85% thermic effect.
Benefits of clear polythene:
Improves the quantity of light to encourage photosynthesis. Encourages early crop yields and crop strength. Increases daytime temperatures.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.
Lumisol Diffused - Diffused Polythene
The diffusion effect ensures better light distribution inside the polytunnel, Diffused Polythene is measured by haze.
The higher the % the cloudier the film is, the more light it defuses.
Our diffused polythene has 90-93% haze.
Our diffused polythene has 87-91% light transmission.
Our diffused polythene has 80-85% thermic effect.
Benefits of diffused polythene:
Reduces the stressful effect of direct sunlight on the plants.
Reduces the risk of leaf burn and crop deformation.
Encourages a more uniform ripening and colouring of the fruit as less shadowing is cast.
Note: designed for use in very luminescent areas of the UK.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.
Over a certain length, commercial tunnels can struggle with stagnant air in the middle of the structure that airflow from open doors cannot circulate.
The best recourse for this is to opt for side ventilation. Whether manual winch, gearbox or motor-driven, it gives the grower control over the environment in the polytunnel.
Opening the side vents allows air to flow throughout the tunnel reducing hot spots in summer. Closing them during cooler months reduces heat loss and encourages the grower
to bring on plants earlier in the year.
Side vents are designed work in conjunction with open doors and/or roof ventilation, allowing full circulation through the tunnel.
Commercial Timber Range
Timber Base Rails
Timber Side Rails
Timber Battens
Full Depth net with PVC skirt
Draft Panels
Manual Gearbox
Aluminium Curtain Tube with Keder Slot
Wind-Up PVC Curtain with double Keder
This is our professional range side vent with a manual gearbox operating the internal roll-up PVC screen. This system is available for polytunnels with timber side rails. The
PVC screen and exterior netting are battened on to the side and base rails using wooden laths. The netting comes complete with a solid draft-proof skirt, draft panels are also
fitted to the mesh where the curtain ends to minimise the cold air entering the tunnel. The PVC Screen fits inside the aluminium drive tube using a Keder bead and is raised or
lowered with a manual gearbox. (An automation option is available)
We only offer sliding doors on our commercial tunnels. Over the years we have learned that doors on polytunnels work better and last longer if they slide rather than swing. We offer 2 models; a low-cost timber framed, clad in polythene and our new heavy duty aluminium frame, clad with PVC. Both versions come with our aluminium profile sliding track and 4-wheel roller carriages.
Low-cost Timber Doors
3” x 2” timber with fixing battons
Polythene cover
Nail plate joints
NP door furniture Door shoes fixing to the posts, drop bolt at the back of the door, door catch,
small channel to hold the together when shut.
Heavy Duty Aluminium
NP designed aluminium door profile with wiggle wire fixing system
Clear PVC top panel
PVC grey lower panel
Steel, bolt on triangle corner plates
PVC finishing strip to cover the perimeter wiggle wire
Brush strip seal at the rear of the door (optional)
NP Designed door furniture, Door shoes to fix to the door posts, drop bolt at the rear of the
door, full length channel section to form a seal between the doors, door catch.
Louvres are easily fitted to the ends of our structures. They can be used in conjunction with doors and the configuration can vary, depending on the size of your structure.
Louvre measurement: 0.79m x 2.12m. Actual ‘opening’ size: 0.8m x 2.15m.
Ventilation Louvres - Pull Cord (Gable end instead of a door)
These feature our unique 3 positional hinge which locks the louvre in place. This allows the louvre to be set in the fully open position, (90°) 1/2 open (45°) or closed.
These can either be single row or a double row (as above) for extra ventilation.
Ventilation Louvres - Rack and Pinion (Above the door)
These louvres feature a rack and pinion system for opening, controlled by a gearbox with winding handle. The rack and pinion louvres are fully adjustable, not just limited to the three positions like the pull cord louvres.
It may seem like an obvious statement, but the more steel in the structure, the stronger it is. How much steel you need can depend heavily on the prevailing weather in your
area. You can use the maps and tables included in this brochure (page 6) to check your average wind speed and snow load. This will help you to determine which kind of crop
bar hangers you should choose; the “Inverted V” for lighter weather loading, or the sturdier “W-Hangers” for heavier weather loading, load bearing apparatus and crop support.
Formed from 50mm and 32mm diameter, Armour-guard coated steel tubing, our crop bars and hangers are just as strong and durable as the hoops they service. Not only do
they pin the hoops together, they prevent lateral movement and joint loosening. When fitted with “W-Hangers”, they’re strong enough to carry direct loading. This is often seen
in retail locations where large numbers of hanging baskets or planters are to be displayed. Crop bars also form the backbone of vital irrigation and air circulation systems as
they are able to carry the additional load of water pipes, heaters and fans.
Our crop bars are just another reason why Northern Polytunnels produce the most robust tunnels on the market, specifically designed to stand up to the worst that the British
weather can throw at them.
V Hangers - Sufficient throughout most of the UK
W Hangers - Used in more extreme locations on wider tunnels
These roof air extraction fans have revolutionised the way that polytunnels can be ventilated. These fans
extract heat from the roof space of the greenhouse at its highest point. Which, in turn, draws cooler, fresher
air in from the doors or side vents creating air movement in the structure. The 240v fans can be connected
to either a simple on off switch, one of our fan controllers or a climate computer.
Click on the image to visit the Roof Fan page
The number of fans required depends upon the volume of warm air you want to expel and how quickly you
want to expel it. As a general guide we would recommend a maximum of one fan for every 350m³ of air
space – this would allow up to 13 air changes per hour. Typically, one fan would be required for every 35ft
to 80ft of polytunnel, depending on the width, height, and existing ventilation systems. For a 30ft (9.14m)
wide polytunnel this would be approx. 1 fan for every 36ft (11m) length of polytunnel. Therefore, a 30ft wide
x 110ft long polytunnel would require a maximum of 3 fans. Even if only a single fan was installed you would
still feel a significant difference as you would still achieve 4-5 complete air changes per hour.
Fan Controller
Click on the image to visit the Roof Fan Controller page
This precise, adaptable and dependable temperature
controller is the ideal partner to any of the air circulation fans
offered in our brochure, allowing for maximum economy and
temperature control.
This robust unit can also be configured to work with heaters
in winter. It’s a fantastic way of keeping simple, but accurate
control over your growing environment.
Function for ventilation in summer
1 Single temperature dial control
From 0° to 30° control
Temperature sensor on a 20m cable
Fan appliances output load 1kw inductive
Can run up to five roof fans
Splash proof IPX4
Optimal ventilation is vital as it plays a significant role in the cultivation of crops. Effective air circulation not only supports but drives crop growth and gives the grower complete
control over the climate inside the tunnel. Mould and fungal diseases thrive on poor ventilation, which is why proper air flow is so important. It’s not all about the heat. On a
humid and sunny day, when the temperature inside the greenhouse rises excessively, it’s important to open the vents to avoid overheating and to spread that cooler air evenly
throughout the tunnel. This can be achieved using circulation fans throughout the structure.
NP overhead irrigation kits utilise the best components we can source including VDL valves and pipework, Netafim down tubes, anti-drip valves and nozzles giving high spray uniformity with minimal wasted water.
Our kit includes 30cm weighted down tubes, anti-drip valves and a nozzles/sprinkler specific to each width of greenhouse, twin 32 mm PVC spray-lines with PVC ball valves on each line, these are connected to a 50mm PVC header manifold
with a drop pipe and connection for a Geka snap coupling.
All straining wires, tensioners and header brackets are included in the kit.
Sprinkler Performance
Each sprinkler is connected to a weighted 30cm down tube this allows the sprinkler to work in a true plumb position for optimum performance.
These are connected to a pressure release anti drain valve, these prevent the water within the sprayline dribbling out after a watering period has ended, saving water and leaving the line ready and primed for the next use.
Benching
Our robust cost-effective benching system is modular meaning that its easily dismantled and reassembled to expand or reduce in size.
The benching comes as a flat pack which is easy to re-site or store when not in use.
The construction is based on our ArmourGuard 25mm diameter tube which has a magnesium zinc coating for years of rust-free life. Our specially designed corner and side fitting gives the bench its modular capability and strength. It is supplied with four corner bracing bars to give extra stability.
The bench top is a hot dipped galvanised mesh with a 3mm wire diameter and hole size of 25mm x 75mm.
Available in 1mtr wide and in multiples of 1.2m lengthways, allowing you to create a continuous bench to suit the length of your polytunnel or plant display area.
Staging
Our staging kits are a low cost solution where a full length bench is required for your polytunnel.
We ONLY provide the steel frame, leaving you to provide your own table-top. Some customers use heavy-duty, galvanised weldmesh, whereas others choose timber slats. Whatever your choice, our staging kits provide the ideal framework on which to grow your potted plants. Supplied with fasteners for fixing timber slats.
Our staging can be installed in new and existing polytunnels.
The Danish Trolley track and ramp is easy to lay and move, and can be used as either a permenant or temporary track. The interlocking sections (end to end) ensure smooth and quiet trolley movement and are supplied in 1.2m x 0.54m interlocking lengths. The track is heavy-duty,long-lasting and made from recycled plastics, with a built-in anti-slip surface along the centre.
Quantity = length of the tunnel ordered
With less than 5% light transmission, ground cover is an effective weed control fabric. Manufactured from black polypropylene (100gm/m2) with 25cm x 25cm green grid lines for accurate plant spacing.
Optimum water permeability (15ltr/m2/second). Ideal for above-ground or below-ground applications.
Sizes Available
Technical Specs
Construction Guide Polythene Specifications
Not all polytunnels are built the same
With over 50 years of experience designing and manufacturing polytunnels, we know that quality counts, that’s why we build our polytunnels to last. If you are comparing us on price against a competitor, you must look at the detail of what you are actually buying, here are some tips on what to look for:
Our 4-piece hoop is made up of a 2-piece arch connected to a straight leg. The leg connection is located on a vertical plane meaning the hoops can withstand a heavier load. Manufacturing a hoop in this way also makes the hoop more customisable by giving the customer the ability to increase the height of the straight leg without compromising the stability of the single span.
Other manufacturers of Polytunnels often have their connections on the curve of the hoop which compromises strength and allows the hoop to ‘snake’. To combat this, extra bracing brackets are used resulting in increased materials, labour and cost.
Aluminium is free from defects that wood has (knots, splits and bows) and will last a lifetime. All our aluminium profiles incorporate our unique ‘W-Wire’ polythene securing system. By simply weaving the ‘W-Wire’ into the open channel of the aluminium rails & frames the polythene is securely trapped in to place. ‘W-Wire’ is the easiest and quickest system on the market and doesn’t require any specialist
tools.
Our timber is fully tanalised to reduce the speed of rotting.
Internal Single Span with Wooden Side and Base Rails
External Single Span with Wooden Side Netted Vent
Wooden 18ft Wide Single Span
High Sided Single Span
Greenhouse Wind and Snow load performance
We strive to give our customers the best product. For this reason, we
undertook the huge task of analysing the strength of our polytunnels.
This is done creating a computer-generated model of the structure
and applying loads from the relevant standards shown in the table
opposite.
These loads are applied to the model of the greenhouse using our
structural analysis software. The software helps us to locate potential
weak spots so that we can optimise our design.
Check If The Polytunnel Suits Your Location
The table below shows the wind and snow load numbers, the higher the number
the stronger the greenhouse required.
Using the maps, pinpoint where your structure is to be
sited; note the colour and zone. Each zone relates to snow loading
and wind speed throughout the country. Check the polytunnel wind
and snow load performance table to make sure the polytunnel will
perform in the area you have pinpointed.
If you need further help with this, please don’t hesitate to get in touch
with our sales team.
(Please note these snow and wind loadings do not apply to our Budget Competitor Range of structures
These Calculation Are Based On The Following Standards
1 Drawings by N P Structures Ltd.
2 EN 1993-1-1:2005, General rules and rules for buildings
3 BS EN 1991-1-3:2003+A1:2015, UK NA General actions – Snow loads
4 BS EN 1991-1-4:2005+A1:2010, UK NA – General actions – Wind actions
5 EN 13031-1:2001, Commercial production greenhouses
Our Single Span Polytunnel Features
The strength of our brackets and fittings have been proven for over 40 years and have been specially designed and manufactured in-house.
Bespoke fittings are designed to simplify the construction process, thereby reducing the construction cost.
ArmourGuard® is NP Structure’s developed high-endurance galvanising treatment, giving extraordinary levels of corrosion resistance. ArmourGuard® offers up to 20 times the corrosion resistance of traditional zinc galvanising due to the combination of zinc, aluminium and magnesium.
Different crops and growing systems require different solutions, which is why we offer a range of options to suit your individual requirements and budget. Options include; doors & louvres - foundations - brace and crop bars - choice of polythene covers - ventilation systems
and irrigation.
Visqueen’s British made polythene allows UVB to enter the greenhouse unlike normal glasshouse films and glass. This has many benefits including enhancing the fragrance, taste, colour of crops with the added advantage of earlier harvesting and longer post-harvest shelf life. It also has a unique condensation reduction additive to further reduce light-loss.
Our polythene is guaranteed for 7 years*
*incremental guarantee from invoice date
Our ground tubes (Foundation Tubes) are 1m long, they are ArmourGuard galvanised treated with a 2.5mm wall thickness.
The image shows a ground tube concreted in with a retaining bar to hold it securely
All of our foundation options incorporate our unique polythene cover tensioning system. The collar tensioning system enables quick and easy tensioning of the polytunnel cover.
The hoops sleeve over the foundation tubes allowing each hoop to be raised individually and locked into position after the polythene sheet has been attached. This stretches the polythene cover to create a drum-tight like cover finish. Unlike some competitors, our system allows easy tightening and slackening throughout the lifespan of the polytunnel
Our Single Span Polytunnel Options
Polythene film: Diffused or Clear?
Light Transmission
Light transmission is the quantity of light going through the polythene, measured by %.
For temperate climates, a rate of higher than 85% is the target.
Thermal Efficiency
Where the heat in the tunnel is retained during the night.
This is measured by thermal retention + thermal transmission = 100 and is expressed as %.
The higher the thermal efficiency, the better the polythene retains heat.
The higher the thermal transmission the more energy is lost.
Anti-Drip
The anti-drip coating reduces condensation droplets and produces more of a film of water.
Benefits of Anti-Drip
Reduces the risk of droplets then dripping which can cause fungal diseases.
Improves the quality of light for photosynthesis, Droplets of water cause light refraction reducing the quality of light.
Note: requires adequate management of the internal micro-climate through ventilation.
Lumisol Clear - Clear Polythene
The clear polythene improves the passage of light into the tunnel to promote photosynthesis.
Clear polythene is measured by haze. The lower the % the clearer the polythene appears and the more light is allowed to be transmitted.
Our clear polythene has 30-35% haze.
Our clear polythene has 88-92% light transmission.
Our clear polythene has 80-85% thermic effect.
Benefits of clear polythene:
Improves the quantity of light to encourage photosynthesis. Encourages early crop yields and crop strength. Increases daytime temperatures.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.
Lumisol Diffused - Diffused Polythene
The diffusion effect ensures better light distribution inside the polytunnel, Diffused Polythene is measured by haze.
The higher the % the cloudier the film is, the more light it defuses.
Our diffused polythene has 90-93% haze.
Our diffused polythene has 87-91% light transmission.
Our diffused polythene has 80-85% thermic effect.
Benefits of diffused polythene:
Reduces the stressful effect of direct sunlight on the plants.
Reduces the risk of leaf burn and crop deformation.
Encourages a more uniform ripening and colouring of the fruit as less shadowing is cast.
Note: designed for use in very luminescent areas of the UK.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.
Over a certain length, commercial tunnels can struggle with stagnant air in the middle of the structure that airflow from open doors cannot circulate.
The best recourse for this is to opt for side ventilation. Whether manual winch, gearbox or motor-driven, it gives the grower control over the environment in the polytunnel.
Opening the side vents allows air to flow throughout the tunnel reducing hot spots in summer. Closing them during cooler months reduces heat loss and encourages the grower
to bring on plants earlier in the year.
Side vents are designed work in conjunction with open doors and/or roof ventilation, allowing full circulation through the tunnel.
Commercial Timber Range
Timber Base Rails
Timber Side Rails
Timber Battens
Full Depth net with PVC skirt
Draft Panels
Manual Gearbox
Aluminium Curtain Tube with Keder Slot
Wind-Up PVC Curtain with double Keder
This is our professional range side vent with a manual gearbox operating the internal roll-up PVC screen. This system is available for polytunnels with timber side rails. The
PVC screen and exterior netting are battened on to the side and base rails using wooden laths. The netting comes complete with a solid draft-proof skirt, draft panels are also
fitted to the mesh where the curtain ends to minimise the cold air entering the tunnel. The PVC Screen fits inside the aluminium drive tube using a Keder bead and is raised or
lowered with a manual gearbox. (An automation option is available)
We only offer sliding doors on our commercial tunnels. Over the years we have learned that doors on polytunnels work better and last longer if they slide rather than swing. We offer 2 models; a low-cost timber framed, clad in polythene and our new heavy duty aluminium frame, clad with PVC. Both versions come with our aluminium profile sliding track and 4-wheel roller carriages.
Low-cost Timber Doors
3” x 2” timber with fixing battons
Polythene cover
Nail plate joints
NP door furniture Door shoes fixing to the posts, drop bolt at the back of the door, door catch,
small channel to hold the together when shut.
Heavy Duty Aluminium
NP designed aluminium door profile with wiggle wire fixing system
Clear PVC top panel
PVC grey lower panel
Steel, bolt on triangle corner plates
PVC finishing strip to cover the perimeter wiggle wire
Brush strip seal at the rear of the door (optional)
NP Designed door furniture, Door shoes to fix to the door posts, drop bolt at the rear of the
door, full length channel section to form a seal between the doors, door catch.
Louvres are easily fitted to the ends of our structures. They can be used in conjunction with doors and the configuration can vary, depending on the size of your structure.
Louvre measurement: 0.79m x 2.12m. Actual ‘opening’ size: 0.8m x 2.15m.
Ventilation Louvres - Pull Cord (Gable end instead of a door)
These feature our unique 3 positional hinge which locks the louvre in place. This allows the louvre to be set in the fully open position, (90°) 1/2 open (45°) or closed.
These can either be single row or a double row (as above) for extra ventilation.
Ventilation Louvres - Rack and Pinion (Above the door)
These louvres feature a rack and pinion system for opening, controlled by a gearbox with winding handle. The rack and pinion louvres are fully adjustable, not just limited to the three positions like the pull cord louvres.
It may seem like an obvious statement, but the more steel in the structure, the stronger it is. How much steel you need can depend heavily on the prevailing weather in your
area. You can use the maps and tables included in this brochure (page 6) to check your average wind speed and snow load. This will help you to determine which kind of crop
bar hangers you should choose; the “Inverted V” for lighter weather loading, or the sturdier “W-Hangers” for heavier weather loading, load bearing apparatus and crop support.
Formed from 50mm and 32mm diameter, Armour-guard coated steel tubing, our crop bars and hangers are just as strong and durable as the hoops they service. Not only do
they pin the hoops together, they prevent lateral movement and joint loosening. When fitted with “W-Hangers”, they’re strong enough to carry direct loading. This is often seen
in retail locations where large numbers of hanging baskets or planters are to be displayed. Crop bars also form the backbone of vital irrigation and air circulation systems as
they are able to carry the additional load of water pipes, heaters and fans.
Our crop bars are just another reason why Northern Polytunnels produce the most robust tunnels on the market, specifically designed to stand up to the worst that the British
weather can throw at them.
V Hangers - Sufficient throughout most of the UK
W Hangers - Used in more extreme locations on wider tunnels
These roof air extraction fans have revolutionised the way that polytunnels can be ventilated. These fans
extract heat from the roof space of the greenhouse at its highest point. Which, in turn, draws cooler, fresher
air in from the doors or side vents creating air movement in the structure. The 240v fans can be connected
to either a simple on off switch, one of our fan controllers or a climate computer.
Click on the image to visit the Roof Fan page
The number of fans required depends upon the volume of warm air you want to expel and how quickly you
want to expel it. As a general guide we would recommend a maximum of one fan for every 350m³ of air
space – this would allow up to 13 air changes per hour. Typically, one fan would be required for every 35ft
to 80ft of polytunnel, depending on the width, height, and existing ventilation systems. For a 30ft (9.14m)
wide polytunnel this would be approx. 1 fan for every 36ft (11m) length of polytunnel. Therefore, a 30ft wide
x 110ft long polytunnel would require a maximum of 3 fans. Even if only a single fan was installed you would
still feel a significant difference as you would still achieve 4-5 complete air changes per hour.
Fan Controller
Click on the image to visit the Roof Fan Controller page
This precise, adaptable and dependable temperature
controller is the ideal partner to any of the air circulation fans
offered in our brochure, allowing for maximum economy and
temperature control.
This robust unit can also be configured to work with heaters
in winter. It’s a fantastic way of keeping simple, but accurate
control over your growing environment.
Function for ventilation in summer
1 Single temperature dial control
From 0° to 30° control
Temperature sensor on a 20m cable
Fan appliances output load 1kw inductive
Can run up to five roof fans
Splash proof IPX4
Optimal ventilation is vital as it plays a significant role in the cultivation of crops. Effective air circulation not only supports but drives crop growth and gives the grower complete
control over the climate inside the tunnel. Mould and fungal diseases thrive on poor ventilation, which is why proper air flow is so important. It’s not all about the heat. On a
humid and sunny day, when the temperature inside the greenhouse rises excessively, it’s important to open the vents to avoid overheating and to spread that cooler air evenly
throughout the tunnel. This can be achieved using circulation fans throughout the structure.
NP overhead irrigation kits utilise the best components we can source including VDL valves and pipework, Netafim down tubes, anti-drip valves and nozzles giving high spray uniformity with minimal wasted water.
Our kit includes 30cm weighted down tubes, anti-drip valves and a nozzles/sprinkler specific to each width of greenhouse, twin 32 mm PVC spray-lines with PVC ball valves on each line, these are connected to a 50mm PVC header manifold
with a drop pipe and connection for a Geka snap coupling.
All straining wires, tensioners and header brackets are included in the kit.
Sprinkler Performance
Each sprinkler is connected to a weighted 30cm down tube this allows the sprinkler to work in a true plumb position for optimum performance.
These are connected to a pressure release anti drain valve, these prevent the water within the sprayline dribbling out after a watering period has ended, saving water and leaving the line ready and primed for the next use.
Benching
Our robust cost-effective benching system is modular meaning that its easily dismantled and reassembled to expand or reduce in size.
The benching comes as a flat pack which is easy to re-site or store when not in use.
The construction is based on our ArmourGuard 25mm diameter tube which has a magnesium zinc coating for years of rust-free life. Our specially designed corner and side fitting gives the bench its modular capability and strength. It is supplied with four corner bracing bars to give extra stability.
The bench top is a hot dipped galvanised mesh with a 3mm wire diameter and hole size of 25mm x 75mm.
Available in 1mtr wide and in multiples of 1.2m lengthways, allowing you to create a continuous bench to suit the length of your polytunnel or plant display area.
Staging
Our staging kits are a low cost solution where a full length bench is required for your polytunnel.
We ONLY provide the steel frame, leaving you to provide your own table-top. Some customers use heavy-duty, galvanised weldmesh, whereas others choose timber slats. Whatever your choice, our staging kits provide the ideal framework on which to grow your potted plants. Supplied with fasteners for fixing timber slats.
Our staging can be installed in new and existing polytunnels.
The Danish Trolley track and ramp is easy to lay and move, and can be used as either a permenant or temporary track. The interlocking sections (end to end) ensure smooth and quiet trolley movement and are supplied in 1.2m x 0.54m interlocking lengths. The track is heavy-duty,long-lasting and made from recycled plastics, with a built-in anti-slip surface along the centre.
Quantity = length of the tunnel ordered
With less than 5% light transmission, ground cover is an effective weed control fabric. Manufactured from black polypropylene (100gm/m2) with 25cm x 25cm green grid lines for accurate plant spacing.
Optimum water permeability (15ltr/m2/second). Ideal for above-ground or below-ground applications.
Sizes Available
Technical Specs
Construction Guide Polythene Specifications
Why Choose An NP Single Span Polytunnel?
U.K. Manufactured from the brackets to the polythene.
Our 4-piece hoop is made up of a 2-piece arch connected to a straight leg. Making them stronger and able to withstand a heavier load
Armourguard Coated Steel Framework – Galvanised to last a lifetime
Foundation Tubes - 2.5mm thick (others use 1.5mm)
Unique Polythene tensioning system - Allows the polythene to be tensioned or loosened as needed throughout the year
Lumisol Polythene - A British made, 7 layered polythene that has been specifically engineered for the British weather
Tanalised Timber - Door frames and Side and Base Rails
Single Span Polytunnel Sizes
Found Your Perfect Single Span?
Our Single Span Polytunnels are made to order and therefore are dispatched within three to four weeks, so you can get your crops started sooner than you think!
If you want to talk to our in-house experts, call today and they will happily help you find a single span tunnel from our range to suit your needs.
