Options

Polyhouses.com offer a comprehensive range of options to add to your choice of Polyhouse framework, to give you the ideal growing environment for your crop. The Polyhouse steel framework kit includes foundation tubes, hoops, ridge and bracing as well as all necessary fittings including fittings for attaching timber end frames. On Multispan Polyhouses gutters are also included.

Timber End Frames

Single span Polyhouses are available with or without timber end frames, allowing you the option of designing or supplying your own end frame arrangement. The standard frame supplied is as depicted on the relevant model specification. Timber for your own design can also be ordered from our sundries website, www.nurserybitz.co.uk

Claddings for Polyhouses

Please note we strongly recommend the use of anti hot-spot tape with all claddings. To this end, this tape is included in the price of polythene when purchasing a new structure. To simplify pricing we offer Standard film (choose between White or Clear film) or Advanced film (choose between Politherm + or Luminance). All these options are Visqueen films. By special request we can supply XL Opico film if preferred. All these films come with a five year guarantee.

Netting is also offered as a tunnel cladding.

1. Standard Visqueen polythene 180mu (720g) ultra violet inhibited films. These are available as Clear film or White film for shade. The standard clear film has a light transmission of 89% and the White 70%. For most salad crops and bedding plants we normally recommend Clear. White is often ideal for Nursery Stock and other shade loving crops.
2. Advanced Visqueen ultra violet inhibited film. Politherm + 180mu (720g) is used for its anti- condensate and heat retentive properties. See our section on energy saving for more details. This film has also been improved lately with the added benefit of broadband ultra-violet light absorption. This feature helps control spore production as well as assisting in the control of certain insects, as UV light is important to insect vision. This film is good for crops where early yield is important and where there is influence by direct light levels and temperatures. Luminance THB AF 200mu (800g) is used for its anti- condensate and high diffusion properties plus its ability to reduce the proportion of short wave length infra red light. These features help reduce scorching, reduce maximum temperatures in sunny weather and increases light to the plant due to its high levels of diffuse light. It has proved to be particularly effective for ornamentals and hardy nursery stock.
3. Netting sheets for Polyhouses can be made from various types of net, monofilament or tape. Both of these are generally green in colour but black can also be available. These sheets are sewn to size as required.

Other commonly used coverings

Nicotarp

This woven polythene fabric with its distinctive striped pattern which is generally green and white, is often used over display type areas where fire retardant fabrics are not required. The light transmission value is around 48% and therefore not suitable for growing under. However the look and feel of buildings clad with this material gives an excellent retail atmosphere.

Green/white co-extruded films

This is used for mushroom houses and storage buildings. If necessary, layers of fibreglass insulation can be used between the sheets for excellent energy saving potential.

Energy Saving Systems.

There are three main possibilities for saving energy in our Polyhouses.

1. Advanced polythene films such as Politherm +.
2. Air inflated double skinned polythene.
3. Internal or external thermal screen systems (these are described on our sister website www.nurserybitz.co.uk; please look for details).

Energy Saving Films

Visqueen have developed a range of high technology polythene films and the Politherm range has two major benefits.

1. It has an anti-condensate inner layer, which helps to prevent condensation.
2. It has an infrared reflective layer allowing the sun's rays into the Polyhouse, but preventing heat escape. It also saves energy if you are heating the building. Typically an unheated Polyhouse using Politherm will be 3 degrees centigrade warmer than one with standard film.

...And when it comes to the environment

Polythene is totally recyclable. Sheets, which are removed from the Polyhouses, can be recycled in the normal way for use in a variety of suitable applications.

Twin Cladding

Double or twin skinning of Polyhouses offers 50% energy savings.
The Polyhouse is clad in the usual way, but with two sheets of film rather than one. The inner sheet should be kept tight and the outer can be clad slightly slack. The Fordingbridge grip rail system is purpose designed to accept one or two films with purpose designed infills. It is advised that a ground rail of some type is always used with twin skin coverings otherwise the sheets can work their way out of the ground. A Polyhouse can be readily changed from single to twin cladding whenever required.

A small purpose designed pressurisation unit pumps air into the Polyhouse. It is housed in a weatherproof box, which has an air regulator valve and weatherproof switch. A flexible hose is connected into the space between the two sheets and the fan runs continuously. Power consumption is only 80 watts (VA).

The air gaps between the two sheets will vary, but average at around 150mm giving the 50% saving over standard twin skinning. There is around 10% reduction in light values due to the second layer.

Any combination of films can be used, for example white outer, clear inner for nursery stock or standard clear outer, Politherm inner for house plants where maximum light and energy saving may be required.

Anti-Hotspot tape

We recommend the use of anti-hotspot tape between the steel tunnel frame and the polythene cover. This is a white polyester faced foam tape, backed with an adhesive to fix it securely to the upper surface of the steel hoops.

The shiny polyester face has a low co efficient of friction and helps to reduce abrasion between the steel hoops and polythene cover. The white surface of the tape reflects light and with the foam insulation prevents heating of the film by the steel framework. The use of foam tape can extend the life of these polythene films by at least one year.

It is important that anti hot spot tape is replaced every second cladding, as the expected lifetime of the tape is 6-8 years.

Ventilation

It is vital for growth, disease control, and for nursery stock and bedding plant hardiness.

Polyhouses.com offer a wide choice of ventilation, from simple louvre (butterfly) vents to sophisticated motorised roll up side vents on multispans.

Please note these vents require the fitting of either a timber or aluminium mid rail. Prices are shown as an option with each Polyhouse on the relevant web page.

These mid rails come complete with rail for each side of the relevant structure including a minimum 1.2m (4ft) return at each end. Fittings for fixing to the steel framework are also included. The height of these vents is dependant on the hoop profile, though on Euro Polyhouses this would normally be around 1.2m (4ft).

Roll Up Side Vents

These were introduced by Fordingbridge 20 years ago and immediately won two major innovation awards. The system works by the film being wound around a tube, which is normally turned manually by a small gearbox unit. It can also in certain situations be electrically operated. It is a very clean, neat system and can work on a curved side if required.

The unit when manually wound normally operates from within the Polyhouse. These vents can be retrofitted to any Polyhouse if required. The polythene is kept taut at all times and gives a very neat finish. These ventilation options can also be applied to the gable ends of Multispan Polyhouses.

Lift Up Side Vents (available as a non standard option on certain Polyhouses).

The advantage of lift up vents is that the vent opens at the top first. It can however, only work efficiently on vertical sides.

The system draws a blind of polythene from the ground level timber rail to the side rail. A leading edge tube is inserted in the hem of the sheet. The tube is raised and lowered by a system of wire and polyester ropes running over nylon pulleys.

As with the roll up vent, the blind is normally sandwiched between netting and the hoops to prevent wind damage to the film when in use.

Typically the lift up system is 30% more expensive than the roll up system.

Gable End Vents

Apart from using doorway apertures, the larger Polyhouses can benefit from our effective `butterfly vents'. These can be arranged at high level, or low level either side of the doorways in most Polyhouses. Gable end vents have a simple spring loaded 3-position hinge stay for variable ventilation rates. Panels are joinery made from pressure treated timber.

Other permutations may be possible on certain Polyhouses. Do not forget that our roll up sides can be used on gable ends of multispans if there are not to many door apertures.

Ground Rails

Polyhouses.com offers a range of aluminium and timber base rail kits and individual components. These can generally be fitted to any make of tunnel provided the foundation tubes are concreted in the ground and the hoop is fixed to the foundation tube. Aluminium rails are a quick and easy system for fixing sheets that cannot be buried in the ground, though a little bit of practice is useful beforehand. Timber rails are a cheaper alternative and are essential to secure a lift-up side vent.

For fixing a roof sheet at ground level, we recommend using our Aluminium Box Base Rail, which is a no additional cost over standard single rail option when purchased with a new structure.

All kits include the necessary components for both sides of a structure.

Aluminium Base Rail Kits are usually positioned at ground level, and comprise aluminium extrusions for clamping to the tunnel frame, fixing bolts and infills.

Timber Base Rail Kits are usually positioned at ground level, and comprise 75mm x 50mm timbers for clamping to the tunnel frame, fixing bolts and battens.

Individual kits and spares are available from our sister site www.nurserybitz.co.uk

Crossbracing

This is available as an optional extra (although some Polyhouses include it as standard); it is a horizontal and vertical bracing arrangement across the span of a hoop. It can increase the resistance to snow and wind loadings particularly in exposed positions and can in some instances be used as a 'crop support' for the hanging of baskets/containers and irrigation lines. Add pic of 9m Euro showing crossbracing

Door options

For smaller Polyhouses many customers will make simple end flaps using their own timber and the polythene supplied with the Polyhouses.

We can supply joinery made timber doors either single or double, low cost hinged, or sliding.

The smaller tunnels (up to l8ft (5.5m) wide) can normally only fit hinged doors because of the lack of width for sliding. Standard door panels are 2m high x 1.2m wide.

For high specification Polyhouses and where timber is considered undesirable we can supply aluminium framed sliding doors, clad with film and if required, with an aluminium base panel and polycarbonate top panel.

All door kits come complete with all parts required, hinges, screws, handles, and on sliding doors our extruded aluminium top track and steel base rail.

Louvre Panels

Apart from using doorway apertures, the larger tunnels can benefit from our effective `butterfly vents'. These can be arranged at high level, or low level either side of the doorways in most structures. Gable end vents have a simple spring loaded 3-position hinge stay for variable ventilation rates. Panels are joinery made from pressure treated timber. Other permutations may be possible on certain structures.

Irrigation

We do offer basic spraylines for self-installation. These are available with either simple pin jet nozzles or the more even coverage micro sprinkler. Further details can be found by logging onto our sister website www.nurserybitz.co.uk

Construction

We do not give construction prices on this site as these can vary depending, for instance, on location, soil type or options chosen. Do contact us for a price if required for any particular project.