I have just constructed a new pergola using pressure treated timber. In the past I have always used Ronseal Fence Life Plus which was ok but recently I notice it can now be sprayed which was not possible before and I now find it is much thinner with less coverage. After 3 coats it still hasn't covered fully and some of it has washed off within 3 months. I notice on many review sites, most users now give it 1 star. I wondered about Cuprinol but that also gets 1 star from most people. I then bought Ronseal Trade 10 year Woodstain, very expensive at £40 for 2.5 litres (8 times the price of Fence Life Plus) but that seems no better. I considered trying Sadolin Classic which is also the same price, but I thought I would turn to this forum first to ask if anyone has found a preservative that is worth the effort. Searching the internet shows there are not too many options. I need something that covers well but will also last a few years because once the roses have grown over, recoating will be difficult/impossible.
Can anyone advise please?