Weed control fabric needed for simple slabbed area?

Weed fabrics are a bit of a misnomer. They stop weeds coming up from underneath but not from weeds growing where dust can settle, like between the cracks. Slabs will stop normal weeds and plants, but not a tree root for example, but then foundations won't stop tree roots if they are determined... My advice would be to spend a few pence on salt. Sprinkle this liberally where you want the slabs to be. It will safely poison anything trying to grow through it and not harm or suffocate most animals. Sorry slugs/snails... Anything that lands between the slabs will try to grow their roots down and then find the salt and be poisoned. I tend to buy a bag of road salt, usually £3-5 and a small area will only need a handful. Table salt works perfectly well too. It is a method to kill plants for millennia and works great. Remaining salt can be sprinkled on driveways/paths etc as a weed killer, just don't put any where you want plants to grow.