Laying out a set of switch back stairs.

I would like to build a set of switch back stairs for my deck. My DEck is about 11ft above the patio The stairs would go away from the house and back to towards the existing patio. The property slopes down from the patio. I am struggling to figure out how to position the footers that will support the 6x6 posts. I haven't been able to find a web site that describes the process well enough that I can follow. I pretty good with math and geometry but hate to make a mistake getting the footers into the correct position.

 

Determine the exact distance down from deck floor to patio. Divide by 2 to get the height of each flight. Determine the rise for each step, which in turn will give the number of steps. The number of steps times the run for each step will determine how far out the landing will be. This is a brief summary. The pros will be along shortly. A sketch of the side view of the top flight will help visualize how the top flight will land on the landing.

 

Yeah, like he said it just takes good planning. Draw it out in both side view and top view... double check your dimensions, once you are sure you have it right I would probably lay a couple long 2x4s on the existing deck that have your layout marked on them... extend them out in midair over where your stairs will be, (make sure you have them parallel with the deck and perpendicular to the side so that they are square in relation to the deck, then screw them down temporarily), then just plumb down with a plumb bob from your layout marks.

Make sure your footing (12" sonotubes are often used) will be centered where the anchors will go. It's pretty common for guys to make the mistake of marking the corner of a 6x6 and then later think that point represents the center of the cement column. (Wrong... it's the corner of a post! The center is 2 3/4" away in both directions) so it might help you if you mark center of post (on your 2x4 layout stick) to center of footing and plumb from there. And the anchors that you set later that have an adjustable post base are a little more user friendly and give you a little wiggle room.

 

Thanks fpr the tips.. A am probablyh a few weeks away from getting to that point . Once I sketch things out, I will upload to make sure I haven't made a stupid mistake.