The strong westerlies in Mayo ripped my Polytunnel to bits agian this December, 2yrs running now, so the time has come to think about Greenhouse. What would your advise be wrt to Strength and would something like what the Walton(UK) Polycarbonate Greenhouses be strong enough for Westport? Big investment so want to make sure it’s still standing next January. See https://www.ebay.ie/itm/220705748069?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
If the wind is that strong, there is a risk to any greenhouse. The only greenhouse that can stand very severe winds is one made of galvanised steel. Aluminium tends to rock and break under severe gusts.
Even a steel greenhouse may need extra struts to reinforce it.
Polycarbonate sheeting is likely to flex and may pop out of its clips.
Glass can pop out too but can be fitted to steel glazing bars with silicone rubber.
The biggest danger to glass is flying debris, which can break glass panels and the strong wind can then blow out the rest of the glass sheets.
A polytunnel can be as robust as most glasshouses especially if long-life sheeting is used, which does not split. And shelter windbreak mesh material can be used.