Table of Contents
A greenhouse film fixing system holds the polythene cover on the frame without nails, staples or timber battens. A channel profile is bolted along the steel. The film is laid over the groove, and a spring wire is pressed in to clamp the edge. The grip then runs along the whole fixing line. As a result, wind load is shared instead of landing on a few puncture points. This guide covers the parts, the profile sizes and six fitting steps. It also lists current shop prices and the checks that keep a cover tight through a dry season. The step-by-step greenhouse construction guide on our main site sets the order of work around this job.
What a Greenhouse Film Fixing System Does
Polythene is flexible by design. On a windy site it lifts, drops and rubs against the frame. Each of those movements works on the fixing points. A cover nailed at 1 m intervals carries the whole load at 1 m intervals. However, a profile spreads that load along every centimetre of the edge.
Three failures follow from a weak fixing. First, the film tears at the holes. Second, the edge pulls out and the sheet flaps. Third, the frame rusts where water enters a puncture or a loose corner. Therefore a greenhouse film fixing system belongs in the structural plan of the house, not in the accessory list. It also decides how quickly a cover can be replaced when its service life ends.
Parts of a Greenhouse Film Fixing System
Six parts make up a working assembly. Check them together. A mismatch between the wire and the channel is the usual reason a fixing fails in its second season.
| Part | Job | What to check |
|---|---|---|
| Greenhouse film | Cover and weather protection | Thickness, UV treatment, sheet width |
| Locking channel | Continuous fixing line on the frame | Groove depth, alloy, surface finish |
| Wiggle wire | Clamps the film inside the groove | Diameter, coating, length |
| Self-drilling screws | Attach the profile to steel | Length, washer, corrosion class |
| Corner brackets | Close the fixing line at corners | Radius match to the frame |
| Profile connectors | Join lengths in long runs | Alignment, gap at the joint |
The channel and the wire are usually sold as one set. In practice, buying them together removes the fit problem. Our greenhouse profiles and wiggle wires listing shows the set the shop carries. Meanwhile, the cover is a separate purchase. Compare the 200-micron greenhouse polythene sheet when you need to match film width to the house.
A greenhouse film fixing system fails at the joints more often than anywhere else on the house. That is why the connectors in the last row of the table deserve the same attention as the channel itself.
Aluminium Locking Channels: Profile Sizes and Finish
The profile is the part that carries the load. Its dimensions therefore matter more than its colour. A channel with a shallow groove lets the wire sit proud. Moreover, the film slips out of a shallow groove under gust load. Ask for the groove depth and the wall thickness before you order a long run.
| Specification | Common option | Why it matters |
|---|---|---|
| Material | Aluminium, sometimes galvanised steel | Weight and corrosion resistance |
| Length | About 4 m, some suppliers 6 m | Fewer joints in long runs |
| Channel | Single groove | Wire seats in one line |
| Finish | Mill finish or coated | Coating slows salt and acid attack |
| Fixing | Self-drilling screws or bolts | Matches the frame material |
Aluminium is light enough for one person to position along a roof edge. Moreover, it does not rust the way untreated steel does. That is why most greenhouse profiles in Kenya are extruded aluminium. A galvanised steel profile is stiffer for the same section, so it suits long unsupported runs. In both cases, the profile should follow the frame without a twist. Bending a channel to close a gap changes the groove, and the wire will not seat afterwards.
The frame under the profile matters too. Our galvanised steel greenhouse range uses hoops that hold a straight line along the eaves. Meanwhile, on a timber house, add a steel strip or a batten behind the profile before you drive the screws.
Wiggle Wire: Diameter, Coating and Grip
Wiggle wire is also called spring wire or lock wire. It is the spring that presses the film into the channel. The wire bends as it enters the groove and then tries to straighten, which is where the clamping force comes from. A wire that is too thin rides out under load. A wire that is too thick will not enter the groove at all.
Three details decide the grip. The diameter must match the channel, and the coating must survive the climate. Galvanised wire is the usual choice for Kenyan greenhouses because humidity and rain attack bare steel quickly. A plastic-coated wire is easier on the film edge. However, the coating can split at the bends after a few seasons. Meanwhile, the length matters at ordering time. A practical rule is to buy wire equal to the total profile length. Then add about 10% for corners, joints and future repairs.
Wire is commonly supplied in 2 m, 3 m and 4 m lengths. Longer pieces mean fewer overlaps along a run, so a 4 m wire pairs naturally with a 4 m profile. Furthermore, the same wire holds insect netting. That is why the insect nets for greenhouses page assumes a locking profile along the vent openings.
Fitting a Greenhouse Film Fixing System in 6 Steps
The sequence below assumes the frame is finished and the ground around the house is clear. Two people can handle a small house, and a larger sheet needs four or more.
- Inspect the frame. Run a gloved hand along every hoop and purlin. Grind sharp weld spatter, cut protruding screw ends and replace bent sections. Any of them will puncture the film on the first windy day.
- Fix the profile. Start at a corner and work away from it. Screw at 300 mm to 400 mm centres and keep the channel straight. Leave a small gap at each joint so the metal can expand.
- Spread the sheet. Lay the film on clean ground, then lift it over the house with ropes. Dragging a sheet across the frame cuts it on the same burrs you just removed.
- Position the edge. Next, pull 100 mm to 150 mm of film over the channel. A narrow allowance pulls out under tension, and an excessive one wrinkles at the wire.
- Press in the wire. Seat one end, then work along the groove with a steady push. Do not hammer the wire, since a dent in the channel will stop the next section seating.
- Check the line. Walk the full fixing line and look for lifted film, uneven tension and loose screws. Correct the faults before the wind tests them for you.
A torn sheet is repaired with tape before the next step. Our greenhouse polythene tape is made for that repair, and a patch holds better on a clean, dry surface.
Film Tension, Roof Edges and Roll-Up Sides
A good greenhouse film fixing system holds the sheet firm without stretching it. Too much tension pulls the wire out at the corners and shortens the life of the film. Too little leaves a pocket that fills with wind. Aim for a sheet that is smooth to the touch and springs back when pressed.
Roof edges take the highest load. Fit a profile along each eave and each gable, not only along the walls. At the ridge, a capping profile closes the joint between two sheets. On the side walls, many Kenyan houses use roll-up sides for cooling. In that case, the fixing design has to allow the lower edge to roll. The film is locked along the top of the opening and left free below it. A side that is locked top and bottom cannot be rolled, and the house loses its main vent. Compare the two designs on the vented vs tunnel greenhouses page before you fix the lower edge.
What a Greenhouse Film Fixing System Costs in Kenya
Price depends on the alloy, the length and the quantity in the order. Our current shop figures for a 4 m profile with its wire are shown below. The saving comes from ordering the full run at once.
| Item | Indicative price per 4 m | Note |
|---|---|---|
| Aluminium locking profile | KSh 500 | Channel only |
| Wiggle wire | KSh 50 | Galvanised spring wire |
| Profile and wire together | KSh 550 | Listed price, regular KSh 650 |
For example, take an 8 m by 24 m tunnel house. Two side walls of 24 m and two end walls of 8 m give 64 running metres of fixing line. That is 16 lengths at 4 m. At the listed price, the profile and wire come to roughly KSh 8,800 before corners and joints. Then add about 10% for offcuts and the spare wire you will want later.
In most budgets, the greenhouse film fixing system costs less than the cover it protects. Compare the film separately. Our greenhouse prices in Kenya page covers the whole house. The 8×24m greenhouse page sets out the component list for that size.
Which Greenhouse Film Fixing System Suits Your Site
Kenya is not one climate. A house in Laikipia faces dry wind, and a house near the lake faces humidity. On the coast, the air carries salt. Each condition pushes a different part of the assembly.
| Site condition | What to specify | Why |
|---|---|---|
| Strong or gusting wind | Deeper channel, screws at 300 mm | Keeps the wire seated under load |
| Heavy rain | Coated profile, galvanised wire | Slows corrosion at the joints |
| High altitude, cold nights | Tight film, no slack at the eaves | Reduces condensation drip on the crop |
| Coastal salt | Coated or marine-grade finish | Bare aluminium pits in salt air |
| Hot lowland | Roll-up sides plus fixing above | Ventilation must stay free to move |
For a commercial block, buy one system for the whole site. Mixing profiles from different suppliers creates wires that fit one channel and rattle in the next. Consequently, spares become a search rather than a phone call. Trade coverage on covering wear is useful background here, and Greenhouse Grower publishes regular material on structures and covers.
Maintenance Checks That Keep the Fixing Tight
Every greenhouse film fixing system needs three checks a season, and one after every strong wind. Ten minutes a month protects an investment that runs into hundreds of thousands of shillings. Look for the following faults.
- Screws that have backed out of the frame
- Wire that sits proud of the channel
- Film pulled thin or white at a corner
- Rust spots on the wire, especially at the cut ends
- Soil or leaves packed into the groove
- Lifted film above a roll-up side
- Torn tape patches that need replacing
First, clean the groove with a brush and a dry cloth. Then rinse salt deposits with clean water, then dry the channel before the wire goes back. If a wire has lost its spring or shows pitting, replace it. A new wire costs a fraction of a new cover. A slack wire is the first stage of a torn one.
Mistakes That Loosen a Cover
Most failures we see in a greenhouse film fixing system trace back to the same five errors. First, the profile is fixed to a bent hoop, so the groove is not straight. Second, the screws are too short and only bite the paint. Third, the film allowance is too small, so the edge slips out. Fourth, the wire is cut short at a corner and the joint is left open. Fifth, the cover is fitted on a windy afternoon. The sheet is then pulled out of line before the wire is seated.
Therefore each error is cheap to prevent and expensive to repair. A straight channel, longer screws, a 100 mm allowance and a quiet morning remove four of the five. The fifth is patience, and it costs nothing.
Frequently Asked Questions About the Greenhouse Film Fixing System
What does a greenhouse film fixing system include?
It includes the locking channel, the spring wire and the screws that hold the profile. Corner brackets and connectors complete the set. The film is bought separately, because sheet width and thickness depend on the house.
How much does a greenhouse film fixing system cost in Kenya?
A 4 m profile with its wire is listed at KSh 550, reduced from KSh 650. An 8 m by 24 m house needs about 16 lengths. That comes to roughly KSh 8,800 before corners and spares.
Can the wire be reused when I replace the film?
Yes, provided the wire is still straight and free of rust. The wire in a greenhouse film fixing system is the most reusable part of the cover assembly. Pull it slowly so it does not kink, store it coiled, and discard any piece that has lost its spring.
Will the system hold insect net or shade net?
Yes. The same channel and wire clamp netting along vents, side openings and roof sections. A knitted net needs a slightly wider allowance than film, so overlap it further before the wire goes in.
Can I fit a profile to a wooden greenhouse?
Yes. First, screw through the profile into a sound timber member and use a washer under each head. Pre-drill hardwood, and replace any softened timber before the profile goes on.
How do I know the film is tight enough?
Press the sheet with a flat hand. It should flex a little and return without a ripple. A visible pocket at the eave means the edge is loose, and a drum-tight sheet means the corner is overloaded.
Buy the Profile and Wire That Fit Your Frame
The shop sells the channel and wire as one set. The greenhouse profiles and wiggle wires page carries the current price. Pair it with the greenhouse film / polythene that matches your house width.
Send the house dimensions, the frame spacing and the wind exposure, and our team will size the run. Call +254 724 775516 or +254 728 163329, or write to info@eunidripirrigationsystems.com. Alternatively, use the contact page and we will reply with a quotation.
A greenhouse film fixing system is the cheapest part of a covered house. It also decides how long the cover lasts. Fit it once, fit it straight, and the next film change becomes an afternoon rather than a rebuild.