Well, you better know how air rises for your vents (I've seen people install tees and crosses upside down), you better know to back off your right angle drill when you start hitting the nails in the headers, you better know how to read blueprints so your drains aren't out of wall and your toilet and shower drains wind up in the right spot, you better know the exterior finish of the house so you can stub out correctly for your outdoor spigots, you better know how to get the proper fall for your trunk line when running a slab, you better not miss any nail plates and you better make sure your fittings are crimped fully and squarely so you're not having to cut out sheetrock and find your leaks when the house is finished, etc, etc...let me guess; Your ABC's... and dodo don't flow up hill ....



