Next Steps, Get it?

Saturday was entirely consumed by my plan to make the lower set of stairs better than the upper set. As I wrote this morning, the idea was to frame and level a box for the first tread, so that all the stringers will be equal.

The problem, as I explained to Casey, is knowing where the stair case will meet the ground. We need the exact height from the ground at the front of the stair to the deck in order to calculate the number of risers. Once we know the number of risers, we know the number of treads is one less. The number of treads dictates where in space the front of the stair is. It's circular. 

My best estimate, from a few days ago, suggested that we need 6R and 5T (unlike the 5R for the upper stairs, and the 5R I had assumed here). Based on that estimate, I drew a careful 1-1/2"=1'-0" section through the stairs. Knowing that the SW corner (lower left in the photo above) would be the lowest point, I decided that the riser at that point would need to be 6.75" like the rest of the stairs. The framing for that first step would taper from there.

Approximate is easy. Any closer to precise is harder than one might think.

I wasn't even sure where that corner would be--extending the line of the west side of the deck (left in the photo) was not as easy as it would be on the drafting table. I came down from the right side, plumb using the level, then measured a distance equal to the width of the stairs as built. My first attempt was crooked because I used just one data point. I thought that a black Sharpie would work, but the concrete needs scrubbing with TSP. 

The edge of the concrete in the photo above is not parallel to the deck, and the rim joist on the right of the photo is part of the prow, so it's angling off in another direction. It's a real world optical illusion, making it very hard to "eyeball" it.

Once I had the tape outline of the first tread, I used a level and a square to calculate the slopes of the bottom of the four boards that would hold up the tread. I cut the long boards first. The bottom of each was cut on a 2.5-degree angle, to accommodate the slope of the concrete. One needed a "shave" to be level--my calculation was off by about 1/4" in 48"--but now they both checked out as level. Trouble is, they were nowhere near level to each other, front to back. I threw out the uphill board and cut it again, because not only was the downhill board level, the western-most corner was the correct height for the 6.75" riser (once a deck board was added).

The sun is setting, but we have a stair tread.

I also worried about that newel post. The typical post has two 1/2" bolts, but the shallow height of the side board would only allow one bolt. (We keep the bolts 2" from the edge of the wood.) Peggy sent me a JLC article on the subject a week ago, and I remembered that it involved a long thru-bolt. My situation isn't like the one in the article, but the long bolt, lots of extra solid blocking, and a bunch of construction screws should make the post pretty sturdy. I haven't installed any of that yet, because I want to make sure the post is plumb in both directions.

In case you're wondering, the newel post has to be in that position relative to the riser board so that it will align with the posts up on the deck. The first small board next to it is just blocking; there will be another block hemming the post in that makes the tread box seem like a simple rectangle. Then there will be two more blocks on the inside in the direction of the bolt tension. The stringers will align with the three little boards to the right in the photo, but the outside (left-most) stringer will align with the blocking that isn't there (so that the stringer's relationship to the posts is maintained).