Replies

1. Expert Member
   MALCOLM TAYLOR | Oct 23, 2022 09:29pm | #1

   andyfrog,

   The extra space required will end up being much more than that. A typical stair doesn't just have a shorter run, it also has a higher rise. So rather than 21 14" treads, you would just have 13 treads at 11".

   But, another way of looking at it is that by making it more pleasant, it becomes usable space like the rest of the house, rather than just something just to transit though carefully to get somewhere else. Add a bookcase on one side, a window seat on the landing...

1. 
   andyfrog | Oct 24, 2022 01:49am | #2

   Ah yes, that's a good point. I was commenting on the study itself, which used three staircases of constant riser height. I wonder why they didn't also adjust the rise height according to popular colloquial rules of thumb:

   "2.2. Staircase apparatus
   Three customized, freestanding staircases were built for the
   testing protocol (Fig. 1). Each staircase consisted of 6 steps with run
   lengths that could be adjusted between 8 and 14 inches. The riser
   height for each staircase was constant (7 inches, 7.5 inches, and 8
   inches, respectively). All corresponding metric measurements for
   the rise and run step dimensions tested are presented in Table 2.
   Handrails were present on the right side for all testing. However,
   participants were instructed to descend the stairs without the use
   of the handrail"

   "Somewhat
   surprisingly, however, the lowest riser height did not result in the
   largest margins of stability. Similar to the findings with respect to
   run length, the position of the centre of mass relative to the step
   edge was the main contributing factor to the stability margin dif-
   ferences (rather than the COM velocity). However, considering the
   very small differences (mean difference in stability margin of
   1.4 cm, in comparison to mean differences as large as 3.1 cm due to
   changes in run length), the result should be interpreted with
   caution. Further work is needed to investigate the relationship
   between riser height and balance control."

   https://tspace.library.utoronto.ca/bitstream/1807/69921/3/Accepted%20manuscript_Novak_ApplErgon.pdf

2. 
   jberks | Oct 24, 2022 11:48am | #3

   Malcolm,

   "...becomes usable space like the rest of the house... Add a bookcase on one side, a window seat on the landing"

   Very cool concept.

   I'm so used to designing in smaller spaces, ie: stairs are very utilitarian to meet space/height requirements.

   I hadn't thought of 'sprucing up the stairs' in terms of functional space before your comment. Thank you.

   Jamie

1. 
   andyfrog | Oct 24, 2022 12:06pm | #4

   A window seat seems like an interesting idea. And for a book case, if you're not in a seismically active area, it could be good too. I would imagine that in an earthquake, however rare, evacuating down stairs that are raining books would be less than ideal.

1. Expert Member
   MALCOLM TAYLOR | Oct 24, 2022 06:06pm | #7

   andyfrog,

   We are smack in the middle of an active seismic zone, and almost every room has floor to ceiling bookcases, including one over the desk I am typing on. I'm a dead man.

2. Expert Member
   MALCOLM TAYLOR | Oct 24, 2022 06:10pm | #8

   Jamie,

   I spent years doing tight space designs, and similarly have a hard time loosening up if there is a bit of extra square footage available. I think that's a great way to be, rather than the converse where you can't make workable tight spaces because you aren't used to constraints.

3. 
   andyfrog | Oct 24, 2022 12:08pm | #5

   Here's some further research I found on stair geometry:
   https://www.sciencedirect.com/science/article/pii/S0966636216301096?via%3Dihub#bib0235
   "Kinesiologic studies have also evaluated the effects of environmental factors on stair negotiation in healthy young adults by experimentally manipulating stair architecture, handrail design, as well as visual cues and lighting. Changes in stair architecture, such as increasing stair height, have been found to further increase the demand of stair negotiation for young adults through enhanced knee and ankle displacements, moments, and powers, as well as increased muscle activations [42], [47]. Increasing stair height or decreasing tread length also decreases center-of-mass stability and time in double support as well as increases ground reaction forces during descent [47], [48]. Young and middle-aged adults self-report a subjective preference for stairs with riser heights of 18.3–21.6 cm and tread lengths of 27.9–30.5 cm [49], [50], but stability of the center of mass relative to the base of support as well as trunk tilt appear optimized for stair heights of no more than 17.8 cm and tread lengths of 33–35.6 cm [48]. Thus, preferred stair dimensions may not be the same as safe stair dimensions that optimize stability."

   https://media.gradebuddy.com/documents/2613981/d97c6312-0a99-4b2f-b30d-d2cbfcac1472.pdf
   "The inclination of the staircase could be readily adjusted
   between 24.0° and 42.0°. At an inclination of 30°, the
   step dimensions were 17.0 cm (riser) by 29.0 cm (tread),
   which is in agreement with values proposed for the design
   of stairs in public environments [18]. At minimum
   inclination, the step dimensions were 13.8× 31.0 cm and
   at maximum inclination they were 22.5× 25.0 cm. Thus,
   tread size changes were small compared to changes of
   riser. No hand railings were necessary because only
   normal subjects were investigated who showed no risk of
   falling"

2. 
   brendanalbano | Oct 24, 2022 01:53pm | #6

   I haven't read this book, but I've seen it come up before in discussions of stair safety: https://direct.mit.edu/books/oa-monograph/5112/The-StaircaseStudies-of-Hazards-Falls-and-Safer

   It looks like all the chapters are downloadable for free!