Question
I have areas around my home (slopes, pool, house perimeter) where I want nothing to grow..what kind of weed fabric do you recommend? Is black plastic better than the fabricks? I would be covering it with gravel or mulch..thanks

Answer
There really is no good reason for using plastic sheets, because it traps moisture and stops air circulation and kills both plants and beneficial soil microbes.  It also promotes the growth of nasty anaerobic (without air) types of bacteria, molds, rot, and fungi.  Plus, it looks ratty as it breaks down over time.

So, weed fabric it is.  

Common mistakes in installation are no overlapping the edges by at least 6 inches, or cutting too-big a plant hole (IF you are planting anything in it - soulds like you are not).  Also, once installed, not using securing pins (especially on a slope), and not covering the weed barrier with a mulch卐xposed fabric will quickly break down in sunlight!

I have no specific brand loyalty, but if you can tear a sample with your hands, so can the weed!  And "heavier" isn't necessarily better.  The "tensile" strength is what deters a plant from poking through. there are several types - woven, spun, impregnated with weed killer, etc...

Since it sounds like you just want a rock-covered slope, I'd either used the impregnated variety, or lay down some granular pre-emmergent first, then the barrier, then the mulch (at least four inches deep, to protect the fabric).

Good luck! Marc