Roundup then polythene perforated with as many holes as you're able to put in it. 

To derail things slightly, will Roundup (or something else ?) kill a creeping crawling, some kind of rose I think thats crawled under all the deck (and who knows where else). Do I need to spray every bit of it I can see ?

rb99:

To derail things slightly, will Roundup (or something else ?) kill a creeping crawling, some kind of rose I think thats crawled under all the deck (and who knows where else). Do I need to spray every bit of it I can see ?

neb:

rb99:

 

To derail things slightly, will Roundup (or something else ?) kill a creeping crawling, some kind of rose I think thats crawled under all the deck (and who knows where else). Do I need to spray every bit of it I can see ?

 

Should take care of most things short of kudzu, and it's systemic so just hit the bits you can see.

Hokey dokey. I'll give it a go. Ta.

@xcon had suggested putting scoria on top of the weedmat, and googling I find a lot of websites (mostly overseas) also saying to put a layer of gravel under the deck as well and that it somehow keeps it drier?

The sites that suggest it seem to think it's an absolute must, but I'd never heard of it before (at least not locally).