Paranoia warning ahead! I've taken up the decking in my back garden and there is a black fibrous membrane underneath. The decking was put down about 15 years ago (I believe - I've not been in the house that long) so I can't believe that there would be any asbestos in the membrane but thought I'd check with the learned members of the forum. Membrane fibres - surely can't be asbestos? The above shot is where the membrane has been bunched up against the fence. In general it is flat and covered with stones. Thanks. Rich.