Wind Doesn't Care That Your Garden Is Sheltered: Funnelling, Gusts and Why Inland Sites Still Fail

Almost everyone who lives inland and has a fence still standing describes their garden the same way: sheltered. It is one of the most confidently offered pieces of information in this trade and one of the least reliable.

The problem is not that people are wrong about their gardens. It is that shelter is judged on ordinary days, and wind damage happens on extraordinary ones — and the relationship between the two is much weaker than it feels. A garden can be genuinely pleasant in a stiff breeze and still receive a severe gust two or three times a winter, and it is those few minutes that decide whether a structure was specified properly.

Buildings Do Not Only Block Wind

The instinct is that surrounding houses shield you. Often they do. Sometimes they do the opposite, and the mechanism is worth understanding because it explains most of the surprising cases.

Air has to go somewhere. When wind meets a row of buildings it cannot stop, so it accelerates through the gaps between them. A passage between two houses, a gate in a solid wall, the space between a garage and a boundary — each is a nozzle, and the air coming out the far side is moving faster than the wind arriving at the front of the terrace. Anyone who has walked between two tall buildings on a windy day has felt this and probably assumed the whole street was like that.

Wind also rolls. Air passing over a building comes down the other side in a turbulent, swirling region rather than continuing smoothly, and a garden sitting in that region receives gusts from directions that make no sense relative to the forecast. This is why people report their veranda being hit by wind "from the wrong way" and are entirely correct.

And shelter can leave. A neighbour's mature line of conifers is doing a great deal of work right up until the morning it is taken out, and no structure is specified on the assumption that somebody else's trees are permanent.

Gusts Are Not Averages

A forecast quotes an average speed and a gust speed, and the gust is what matters, because load rises with the square of speed.

Work an example. A day averaging fifteen metres per second with gusts to twenty-five is not a day sixty per cent worse than average — the gust load is nearly three times the average load. Structures are not damaged by conditions, they are damaged by moments, and a single gust lasting a few seconds carries every bit as much load as the same speed sustained all day.

That is the flaw in judging shelter by feel. A garden that is pleasant in a fresh breeze tells you about average conditions. It tells you very little about the peak, and the peak is what the engineering is sized for.

The reverse case exists too, and it is worth mentioning for fairness. Plenty of gardens genuinely are sheltered — mid-terrace, enclosed on three sides by buildings of similar height, with mature planting that is not going anywhere. Specifying those honestly is just as useful, because it means money is spent on the parts of the structure you will actually enjoy rather than on foundations sized for conditions that will never arrive. The aim is an accurate description, not a pessimistic one.

The Sites That Catch People Out

Some sites feel sheltered and are not, and they repeat often enough to be worth listing in prose.

Gardens backing onto open fields, where the house shelters you from three directions and the fourth has three miles of run-up. Gardens on the brow of a hill, where wind accelerates over the crest and the elevation feels calm because you are looking at the view rather than into the weather. New estates, where the planting has not grown in and the shelter the site will eventually have does not exist yet. Corner plots, which see wind from directions the neighbours never do. And valleys, which channel wind along their length so consistently that a garden can be genuinely sheltered from most directions and badly exposed to one.

None of these are exotic. They describe an enormous proportion of British housing, and the common thread is that the site feels fine on the day somebody stands in it with a tape measure.

What Actually Reduces the Risk

Three things, in descending order of usefulness.

Specifying for the exposed condition rather than the felt one. This is almost always cheaper than people assume at the design stage — the difference is usually foundation size, post count and configuration, not a different product — and impossible to add later without disturbing the parts already in the ground.

Choosing infill you can open. A structure with fixed panels has one configuration. A structure using rotating louvres can be opened flat before a storm, which genuinely reduces what the frame is asked to carry. On the roof, an adjustable system such as a Pinela Tilt gives you a similar option in the vertical plane — the ability to change the structure's presented shape for a couple of days a year is worth more than it sounds.

And respecting the operating limits of anything fabric. External blinds come with wind ratings and retraction guidance, and those are not warranty small print. They are the conditions in which the product works. A blind left out in a storm is comfortably the most likely component on any veranda to be damaged, and it is the one entirely within your control.

Direction is worth thinking about separately from strength. Prevailing wind in most of the UK comes from the south-west, and it is the direction most gardens are informally organised around — it is where the fence has been reinforced and where the planting has grown up. But the most damaging wind on a given site is not always the prevailing one. A structure well sheltered from the south-west and wide open to the north-east is in a common and slightly awkward position, because the shelter is real and it is pointing the wrong way.

How to Describe Your Site Honestly

You do not need instrumentation. You need to answer four questions accurately rather than optimistically.

What is beyond your boundary in each direction, out to a few hundred metres — houses, open ground, water? Are you level with your neighbours, higher, or lower? Is the shelter you are relying on permanent, or is it vegetation and fence panels? And what actually happens in your garden in bad weather — does the trampoline move, does the fence flex, has anything ever gone over?

That last question is the most useful of the four, because it is observation rather than assumption, and people almost always know the answer without having thought to volunteer it. Tell your supplier all four and the specification can be right. Say "it is quite sheltered here" and you are describing a Tuesday in June.