RISR2

RISR2

This routine will calculate detailed stringer and platform information given:- F2F in FIS (the finished floor to finished floor height)- Riser Count- Tread Length

Items calculated by this routine, in no particular order, are:- Fire Blocking lengths for stud walls at 12” o.c. and 16” o.c. (long to short/along the top)- Each accumulated diagonal length of each tread/riser in progression.- The Main Diagonal length from first to last of the “saw tooth” cuts.- The total Run of the stairs in FIS and in decimal inches- The Common Pitch (__:12) of the stringer.- The Slope in degrees of the stringer.- The exact Riser height in decimal inches.- The lengths in sequence of each step/platform from the finished top of each tread vertically down to

the finished floor.

Here is what the actual routine looks like when keyed into the calculator.

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As with all of these routines, the user is “prompted” to enter the required numbers so that the calculation can be performed.

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The keystrokes to enter/store, in an HP scientific calculator, in RPN mode are below:

<< “F2F FIS” “” INPUT OBJ INSH ‘H’ STO H ‘E’ STO“RISER COUNT” “” INPUT OBJ ‘K’ STO“TREAD SIZE INCH” “” INPUT OBJ ‘T’ STO

H K / ‘R’ STO! DO H FEET H R - ‘H’ STO! UNTIL H 0 ≤! ENDR FEET ‘RISER’ TAGR T / ATAN ‘A’ STOA ‘SLOPE’ TAG A TAN 12 * ‘COMMPITCH’ TAGK 1 - T * ‘S’ STOS ‘RUN’ TAGS FEET ‘RUN’ TAGE R - SQ S SQ + √ ‘B’ STOB FEET ‘MAINDIAG’ TAGR SQ T SQ + √ ‘C’ STO! DO B FEET B C - ‘B’ STO! UNTIL B 0 ≤! ENDR T / 14.5 * SQ 14.5 SQ + √ FEET ‘SIXTEENL2S’ TAGR T / 10.5 * SQ 10.5 SQ + √ FEET ‘TWELVEL2S TAG

CLEER >>

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Here is an example of a real-world set of stairs. The only information required to correctly build the stairs is the finished-floor to finished-floor height, the number of risers, and the tread length.

Using the RISR2 routine, all the relevant information is easily generated and can be written out on a block or notepad.

Additionally, the finished tread elevation information is very useful when building stairs that incorporate a platform at some point in the stairwell.

In the image to the right, if a platform was to be built at the top of the sixth riser height, it would be 3-10-3, or 3’-10 3/16” from the finished floor up to the top of the platform.

So if I was building this platform all I would have to do is subtract the thickness of whatever surface is going on top of the platform framing from that height, and that would be the height of the top of the structural f raming members of the platform.

Also, fire blocking is often required in the walls that surround a stairwell. Typically these walls are 16” o.c. for residential, and often 12” o.c. for commercial framing.

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Something that I started doing to combat pencil line deviation (having the pencil line be too thick or not precisely along the f raming square) was to calculate the diagonal length of each step.

Then, it made sense to have the calculator generate those diagonals as an accumulated total in sequence from one end to the other other.

What this does, is create a self-truing method for correctly locating the framing square

along the stringer.

Starting at one end of the stringer, the framer can set a nail, and pull his tape from that starting point, marking every diagonal until reaching the end. Then it is just a matter of aligning a properly set framing square in between these diagonal marks. This tends to make the stringer as precise/accurate as possible.

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It is typically a good habit to completely mark out a stringer and then only cut the very top and very bottom according to your marks, then do a “dry fit”. I consider this my last check to make sure that the stringer will correctly fit into the stairwell. If it does not fit, by some mistake that I made, then I did not waste a sufficient amount of time cutting all the notches into it.

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I know some framers who then nail a ledger board to the stringer once it is completed and correct. In fact, that’s how I was taught. As I thought about how I wanted to build stairs, like they were going into my own personal house, I realized that it was better to trace a bottom-line along each stud when I dry fit the stringer, then apply glue above that line, on each stud, and finally face nail a properly cut 2x4 ledger to each stud above that line.

Then I could apply glue to the face of that ledger and face nail the stringer when it is flush to the bottom of that ledger.

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RISR2

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Transcript of RISR2