As per the title really, we have a large upvc window unit and door which I want to replace with a bi fold door I have bbeen recommended to get alluminium as they are less inclined to sag! Anyone any thoughts or recomendations?
Just beware the sagging is only one of a number of issues you might have, huge amount of weight in each panel and if you are going to be moving that on a regular basis it can require a lot of moving parts which need to be looked after. If top hung, need to make sure you have a decent lintel in place which can take the fixings. Basically they can be a bit of a maintenance nightmare so find a supplier locally who can provide a an owner willing to show you a set of their doors which have been in place for a good few years.
2nd for Duration - 10 years ago, still look great, 4 panes by 4.5m in total roughly. I bought 18 windows, a bifold, 3 pane sliding patio and a set of french doors, fitted all myself (actually they delivered the bi-folds separately and did the final install of them)