On Sun, 21 Aug 2016 21:18:29 +0100, Stewart Robert Hinsley
[I've bought a steam cleaner for use in the kitchen. I've been thinking
of trying it on "patio weeds".]

I did that last month, been cleaning the barbeque, and experimented
with the block paving. In a small area, that had been treated last
year with 'Block Sealer' there was some moss in the cracks. Did it
work? I need to try it on a larger area, while it worked, not sure if
it was any easier than other methods, but it was cheaper than weed
killer!