Posted: 18/04/2015 at 17:42
I have used both as a windbreak to protect newly planted shrubs till they established. Both types rotted far too easily and broke in strong winds and got tatty very quickly. I would not advise them as a permanent screen.
I would suggest instead that you attach 2' wide trellis panels horizontally to the top of the existing fence or else erect 6' high panels on the inside of the fence, using new posts if necessary. trellis can be painted to make a feature of it or else you can train climbing plants up it for further privacy and added interest.
Local DIY stores and maybe timber yards will stock it so shop around for best prices and quality.