Hey all, apologies if this isn't the right sun, but i thought it'd be a good place to start.

Anyway, I'm in need of a "nuclear option" right now. I've got a deck in my back yard that has all sorts of plants growing through it. Some ivy, some sort of bush and other weeds. I've tried all sorts of methods, from roundup to white vinegar/salt/dish soap. This has sort of worker, in that it kills some of it, but it takes too long and is either being washed away by rain or evaporated before it can fully kill it.

What's worse is I cannot get at the roots/base of the plants since my deck is all of 1 foot off the ground.

Are there any good solutions? I'm looking for something that I could pour/spray in between the boards of the deck that will absolutely kill everything and not let anything grow there again.