I would take a close look at the guarantees on offer from both Sarnafil and which ever GRP company you are looking at. You'll be surprised by what they actually cover and what you can claim for if something goes wrong! It may give you an idea which product you can have confidence in and ultimately give you piece of mind in what you install. Best place to get an idea on environmental impact is through BRE website and look for the BREAAM ratings. Think PVC membranes in general will provide A+ rating. (best you can get)
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!