My canopy moves in strong wind, should I be worried?

Uplift is the load that matters

People assume a roof structure is fighting gravity. In a gale it is often doing the opposite. Wind flowing over a canopy creates lift underneath it, and that lift pulls the fixings out of the wall and the posts up out of their bases. This is why anchorage into sound material matters far more than the apparent strength of the frame, and why a structure that looks heavy duty can still be the one that moves if it was fixed into a soft outer leaf of brick.

Movement that is normal

A wide canopy or a projecting awning cassette will visibly deflect in a strong gust and return. A slight creak as aluminium sections move against each other, particularly as the temperature swings, is also usual. What characterises normal behaviour is that it is even, it happens across the whole structure, and it settles the moment the gust passes. If it has always done it and nothing has changed, it is very likely doing what it was designed to do.

• Even, gentle deflection across the full width
• Movement that returns immediately once the gust passes
• Occasional expansion creaks in changing temperatures
• The same behaviour it has shown since installation

Movement that needs looking at

Concentrated movement is the warning sign. One post that shifts while the others stay put, a wall plate that visibly lifts away from the brickwork at one end, or a new knocking sound in moderate wind all point to a fixing that is no longer holding. Cracked or spalled brick around an anchor, a hairline crack in a slab at a post base, or a gap that has opened between a post plate and the paving are all worth photographing and reporting rather than watching for another season.

• One corner or post moving noticeably more than the rest
• A visible gap opening at the wall plate during gusts
• Cracked brick, render or paving around any fixing
• A new knock or bang in wind that used to be silent
• Any bolt that can be turned by hand

What to do during and after a storm

Retractable awnings should be closed before the wind arrives, because an extended awning is a sail and no fabric awning is a storm structure. Where a canopy has side screens, retract or open them so wind can pass through rather than push against them. Afterwards, a slow walk round from the ground tells you most of what you need: look along the front beam for a new sag, at each post base, and at the wall line for fresh cracking or dust.

1. 1Close any retractable awning and open side screens before the wind.
2. 2After it passes, sight along the front beam for a change in line.
3. 3Check each post base and the paving immediately around it.
4. 4Look along the wall plate for gaps, dust or fresh cracks.
5. 5Photograph anything new so you can compare after the next storm.

Wind sensors, and where they help

Automation genuinely reduces risk on retractable products. A wind sensor retracts an awning when gusts exceed a set threshold, which protects it on the days you are out. It is worth saying plainly that a sensor protects a moving product from being caught out, it does not make a fixed structure stronger. On fixed verandas, the protection comes from the specification and the anchorage chosen at the survey.

A wind sensor protects a retractable awning that would otherwise be left out. It has no bearing on how a fixed canopy handles a gale.

Inherited structures and unknown fixings

We look at plenty of structures fitted by companies that are no longer around, and the honest answer is that you cannot judge anchorage by appearance. Fixings hidden behind a cover strip may be into brick, into mortar joints, or into render with very little behind them. Where movement has changed and there are no records, an inspection that actually exposes a fixing is the only way to know, and it is far cheaper than the alternative.