Greenhouses in High Winds – Protect and Survive!

Although hurricanes are pretty rare in the UK, we do get some high winds and they leave a trail of broken glass and twisted aluminium behind. I’ve seen high winds lift an entire greenhouse and dump it 3 plots away, the glass in shards and the frame looking like a giant has tied knots in it.

Greenhouse Wind Damaged

Two mistakes resulted in this greenhouse being destroyed. First the position is too exposed to the wind and second, the fixing of the frame to the ground was not sufficient.

There’s no way you can build a 100% storm safe greenhouse but there are a number of things you can do to minimise the chance of wind damage to your greenhouse.

Wind Damaged Greenhouse

Just a broken pane in the side and the wind got in and ripped out the glass and glazing bar.

The main problem tends to be the wind gets into the greenhouse and the pressure pushes a pane of glass out. After this the damage cascades. Since the vast majority of us have aluminium greenhouses, that’s where I’ll concentrate.

Ensure your greenhouse is square and level. If the house is out of true then the frame will be and the glass won’t fit properly. Loose glass will rattle, may well break and gaps allow the wind into the greenhouse.

Ensure the base of the greenhouse is fixed to the ground. I set mine up on railway sleepers, which were level, and then screwed the aluminium frame to that. Use a number of fixing points to even the load. If wind does get into the house then it won’t be able to lift the house.

Between the aluminium and the glass there will be a flexible glazing seal. Over the years these tend to perish and often go missing when a greenhouse is moved. They perform two tasks: holding the glass firmly and preventing wind penetration between loose glass and the frame. If the seals are missing or perished, replace them. Ebay is a good source.

Greenhouse Roof Blown Off

This greenhouse was under construction when the storm hit. The glazed top was ripped off by the wind but the frame is OK under.

The glass itself should be checked. Cracked panes should be replaced and never leave a gap where a pane is missing. Do remember glass gets brittle with age and breaks more easily. Always wear protective gloves when handling glass, it’s so easy to really slice yourself badly.

The glazing clips that hold the glass in place have a habit of vanishing. It’s well worth keeping some spares in stock and replace them as required. Often just two clips are used on a standard 2′ x 2′ pane but you’ll be better off with four glazing clips per pane.

When a storm is forecast, ensure all the windows and doors are firmly shut. Automatic window and vent openers are a boon but if they open the window in a warm weather storm then the wind will get in, so disconnect them for the danger period.

If you’ve done everything above then hopefully your greenhouse will be fairly safe from wind damage. There are a couple of other things you can do to have a greenhouse in windy places.

If you can site the greenhouse so the prevailing wind flows over rather than at the end. If you have a sheltered spot, perhaps in the wind shadow of trees it can be worth sacrificing some sunshine for the protection. You could also consider erecting a wind break to shelter the green house.

When you’re buying a new greenhouse for a windy place, then go for the toughened safety glass which comes in larger panes and is stronger in itself. It’s also easier to keep clean and if it does break, it breaks into small pieces rather than large sharp shards. Go for continuous strip fixings, bar capping, rather than clips to hold the glass in place and look for a strong frame construction.

Greenhouse Growing, Coldframes etc. Further information

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