Wind season in Gauteng: what fails, and why
July to September is when my phone rings the most. And in almost every one of those calls, the netting is not what gave in first. It is the last thing to go, not the first.
Gauteng does not get storms in winter. What it gets is weeks of dry, steady, dusty wind, and then a run of gusts that arrive from nowhere on an otherwise still afternoon. That combination is harder on a shade structure than a summer thunderstorm, because the damage builds up quietly and then shows itself all at once.
What the wind actually does here
The average wind speed through our windy months is not dramatic on paper. It is the gusts that matter, and the gusts are several times the average.
| Month | Average | Typical gusts |
|---|---|---|
| July | 9 km/h | up to 30 km/h |
| August | 10.7 km/h | 30–35 km/h |
| September | 11.3 km/h | up to 40 km/h |
Typical figures for the Gauteng highveld through the dry season. Individual sites vary a lot — an open industrial yard behaves nothing like a walled suburban driveway.
A shade net is a sail. It does not stop the wind, it catches it and passes the load into the cables, the stitching and the steel. At 10 km/h you will barely see it move. At 40 km/h every weak point on the structure is being tested, repeatedly, for as long as the gust lasts. Wind load does not climb in a straight line with speed either — doubling the speed puts far more than double the force into the frame.
The order things fail in
After years of going out to these, the pattern barely changes. It goes like this, almost every time.
- Tension goes first. A net slackens gradually over a couple of seasons. Nobody notices, because it happens a millimetre at a time. But a slack net flaps, and a flapping net takes shock loads instead of steady ones.
- Then the stitching. The seams are where the panels join and where the net meets the edge rope. Flapping works those threads loose. Once one seam opens, the tear runs.
- Then the cables and fixings. Shackles work loose, cable clamps slip, eye bolts elongate. All of it is cheap to fix and expensive to ignore.
- The steel, last. A properly built frame with poles set in concrete will normally still be standing when everything above it has let go. That is the point of building it properly.
The one that costs people money
A slack net is not a cosmetic problem. It is the single biggest warning sign of a net about to tear, and re-tensioning is one of the cheapest things on my rate card. Most of the emergency calls I get in August could have been a routine visit in May.
What makes a structure survive it
There is no trick to it. Wind resistance comes from the boring parts being done properly.
- Poles in concrete, not bolted to a slab as an afterthought. The footing is what actually holds the structure down.
- Correct cable gauge, properly tensioned. We use 3 to 5mm galvanised steel cable, sized to the structure rather than to whatever is on the van.
- A net that is tight. Tight means it does not flap. That is the whole specification.
- Netting that has not gone brittle. UV-stabilised commercial fabric holds its strength for ten to twelve years here. Netting past that will tear in wind it used to handle easily.
Our structures are built to handle wind up to around 100 km/h, which is well beyond anything a normal Gauteng winter produces. But that rating assumes the structure is in the condition it was in on the day it went up. Three years of neglect quietly removes most of the margin.
When to look at it
Autumn. April to June, before the wind arrives, is the right time — not August when something has already torn. A walk-around takes ten minutes and it costs nothing:
- Push up on the net from underneath. If it moves easily and keeps moving, it is slack.
- Look along the seams for loose or missing stitching, especially at the corners.
- Check the cables for fraying, and check that the clamps have not crept.
- Look at the base of each pole for movement, rust or cracked concrete.
- Hold a corner of the netting and flex it. If it feels stiff and crackles rather than folding softly, the fabric is at the end of its life.
If any of those look wrong, it is a maintenance job, not a replacement job. That is worth saying plainly, because the industry default is to quote you a new structure. If your steel is sound — and it usually is — a refit, a restitch and a proper re-tension puts you back where you started for a fraction of the money. We maintain before we replace.
Send me a photo of what you have. I will tell you honestly whether it needs work before the wind comes, or whether it is fine to leave.