Frequently Asked Questions

In most cases, planning permission is required for these types of buildings. But, with our in-house design team, we can supply the necessary drawings to make an application.

The size of a polyhouse is taken from the centre of the foundation tubes, down the length of the building. With Single spans, the measurement is the outside of the hoop span to ground level. With multispans, you would take the inner span from the centre of the gutter to gutter.

To ensure you are ordering the correct width of cladding, take the external hoop circumference as your measurement. Unless a ground level rail is being used, the prices we quote take into account the trenching of the polythene or netting at the sides of the tunnel. We also include the cost of the anti-hot spot tape when it is ordered with a new polyhouse framework. If you’re providing your own cladding, you must add at least 0.75m (2ft 6ins) each side to trench into the ground, or at least 0.3m (1ft) if cladding to a side rail.

Please note we strongly recommend the use of anti-hot spot tape between the steel tunnel frame and all claddings as the use of anti-hot spot tape can extend the life of the polythene film. For this reason, we include the tape in the pricing of the cladding when purchasing a new structure. To prolong the life of the polythene, it is important that anti- hotspot tape is replaced every second cladding. Available cladding options include:

BPI Visqueen film

• BPI Visqueen Lumisol ‘Clear’ 5S
  Clear cover incorporating a UV ‘Transparent’ characteristic. This cover transmits a high percentage of UV light which can assist the colour, flavour and fragrance in a wide range of flower and full crops.
• BPI Visqueen Lumisol ‘Diffused’ 5S
  Very high diffusing cover incorporating a UV ‘Transparent’ characteristic. This transmits a high percentage of UV light which can assist the colour, flavour and fragrance in a wide range of flower and full crops. In addition, UV transparent films promote plant anti-oxidants, which are good for health, and encourage stronger plants. This greatly benefits plant raisers and young plant growers as stronger plants can be easier to plant out thus saving time and raising productivity.

Netting sheets

Bespoke sizes made using black tape net or Green monofilament net.

XL Polythene

We offer a complete range of polythene to suit your growing requirements. As well as incorporating technologies to increase the strength of their films, our products offer all the features and benefits of other polythene films.

We recommend that all our polyhouses are anchored using concrete foundations. As a rule of thumb, you will need 1 cubic metre for every 10 foundation tubes. For example, a 7m x 18m would need around 2 cubic metres.

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 depicted on the relevant model specification.

Our polyhouses are sealed to a greater extent than a conventional glasshouse. Ventilation and air circulation is vital for plant growth and health, therefore please select one of the following options for your polytunnel.

• Timber rails
  Timber rails are a low cost, simple system and easy to install. The edge of the film is wrapped around a batten which is then nailed to a timber rail bolted to the polyhouse frame.
• Aluminium rails
  Aluminium rails are an extruded grip rail cladding system for secure flexible sheeting. A base extrusion is secured to the structure framework and the cladding film stretched over it. The extruded aluminium infill section is then inserted into the base securing the film between the two components. Grip rail is extremely versatile and can be used with a wide range of different film thicknesses, simply using a different infill to match the cladding material used. These mid rails come complete with railing for each side of the relevant structure including a minimum 1.2m 94ft) return at each end. Fittings required for fixing the rail to the steel framework are also included. The height of these vents is dependent on the hoop profile.
• Roll up side vents
  Roll up side vents systems work with the film being wound around a tube, which is normally turned manually by a small gearbox unit. In certain situations, it can be electrically operated. This method is a very clean, neat system which can work on a curved side and retro-fitted if required. Roll up sides can also be used on gable ends of multispans if there are not too many door apertures.
• Gable-end vents
  The larger polyhouses can benefit from our effective butterfly vents. These can be arranged at high level, low level, or either side of the doorways in most polyhouses. Gable-end vents have a simple spring loaded 3-position hinge stay for variable ventilation rates. Other permutations may be possible on certain polyhouses, please contact us for details.

We offer a range of aluminium and timber ground rail kits. These can generally be fitted to all tunnels provided the foundation tubes are concreted in the ground and the hoop is fixed to the foundation tube.

• Aluminium box ground rails are a quick and easy system for fixing sheets that cannot be buried in the ground. Kits comprise aluminium extrusions for clamping to the funnel frame, fixing bolts and infills.
• Timber ground rails are a cheaper alternative and are essential to secure a lift-up side vent. Kits comprise 75mm x 50mm timbers for clamping to the tunnel frame, fixing bolts and battens.

Our door kits contain all the parts required; hinges, screws, handles and for sliding doors our extruded aluminium top track and steel base rail. Please note that door kits do not include timber end frames. To establish the correct door and louvre options, please refer to individual products.

• Timber doors
  We can supply joinery made timber doors, either single or double, low cost hinged or sliding. The small tunnels (up to 18ft/5.5m wide) can normally only fit hinged doors because of the lack of width for sliding. For these smaller tunnels the standard door panels are 6.6ft (2m) high and approximately 1.2m wide. For tunnels 21ft (6.4m) and wider, the doors are 6.9ft (2.1m) high.
• Aluminium doors
  We can supply aluminium framed sliding doors, clad with rigid polycarbonate and an aluminium base panel.

Anti-hot spot tape 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 hoop 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.

Cross-bracing 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.

A swage is where the tube end is reduced in diameter for approximately 100mm along its length. This allows tubes to sleeve together giving a low cost, extremely strong joint which is fast to assemble. The foundation tubes to hoops, the hoops themselves and the ridge and cross-braces use this swage system.

Please contact us regarding delivery. The delivery cost and lead time will vary according to location.

Our in-house logistics enables timely and UK mainland deliveries. Although deliveries are expected to take between two to three weeks, please note that at exceptionally busy times this may vary.

All our agents will be delighted to advise you on your choice of structure and to assist with any queries and orders. Please find agent details here.

Please refer to your local agent for full terms.

Polyhouses.com is committed to ensure the Health, Safety and Welfare of everyone involved in the building and recladding of our polyhouse structures.

Under the Work at Height regulations 2005, employers and those in control of any work at height activity must make sure work is properly planned, supervised and carried out by competent people.

Single span polyhouses

Single span polyhouses can be built and clad without any specialised equipment as access to all sides should be available from ground level. However, on higher sided polytunnels risk assessments must be carried out by a competent person and control measures put in place, where necessary, to ensure a safe system of work. This may mean using equipment such as scaffold towers or scissor lifts.

Twin and multispan polyhouses

The construction of twin and multispan polyhouses involves a higher number of safety measures to ensure the safety of personnel. In this instance, the highest risk comes from falls from height when operatives are gaining access to, walking in and working from the valley gutters. As these hazards cannot be eliminated, the only viable safe system of working is from within the gutter.

To mitigate any falls from height, safety nets must be fitted to the structure on either side of the valley. It has been established that the most efficient layout of the nets is to have one either side of a valley gutter, fixed to each post at the gutter and secured to the ridge bar in an upward direction to maintain an incline of the nets to minimise any fall height. No gaps or obstructions; e.g. support canes, benches etc, underneath are permitted in the netting that would allow someone to fall through.

Re-cladding or refurbishing

If cladding or recladding a twin-span polytunnel, two nets will be required. If building or refurbishing a Multispan structure, then a minimum of four nets will be required. When the first two spans have been successfully clad, two of the nets can be moved to the next unprotected valley gutter.

Old polythene, due to age and ultraviolet breakdown, becomes very brittle and will not sustain the load of someone falling against it. Similarly, new polythene may seem strong enough but if pierced a tear line will form if weight is applied.

Under no circumstances should walking the gutter of a clad framework without netting underneath be deemed a safe working platform.

These structures have fragile roofs and any access for maintenance or repair must be carefully risk assessed and work carried out by trained and competent people.

If you have any further concerns about health and safety and our polyhouses, please contact us or check the HSE website’s guide Working safely at height (PDF, link opens in new window).