Stair Vignette Riser Height

Ramp, Stair, & Roof Vignettes and Multiple Choice

Stair Vignette Riser Height

Postby crishe3 » Sun Dec 14, 2014 7:14 pm

Is the riser height supposed to be consistent for all the steps of the stair? I had prepared for a 7" riser but when I got into the test the first landing dictated a riser height that would not work with a 7" riser. I was under the impression that all the risers of the stair needed to be the same height. I never thought they would give anything other than a 7" rise and it took me the entire time to figure this stair out because of this. I finished the vignette with 4 seconds left, hopefully I did not make any fatal errors. I have taken and passed the rest of the exams and due to the unexpected riser height, this vignette was by far the hardest. Do all the riser heights for the stair need to be the same height? If they do not, then this would have been a lot easier. I have just never come across anyone that had something other than a 7" riser so I did not know what to do in the exam. Can someone clear this up for me?
crishe3
 
Posts: 6
Joined: Tue May 21, 2013 8:39 am

Re: Stair Vignette Riser Height

Postby examslayer » Sun Dec 14, 2014 7:28 pm

This is a really good question. I suppose it depends on your definition of a "flight of stairs", whether you define it purely as all of the stairs between two floors, or if you define it as those that are uninterrupted between landings. I would lean toward the latter because I don't think it makes sense to have to spend all your time making sure the stairs are the same height, instead I think the goal of the exam is to test your ability to follow all of the instructions and use the code to make an accessible stair. I'd be very curious to hear what others think.

The code says "Treads shall be of uniform depth and risers of uniform height in any flight of stairs"
examslayer
 
Posts: 28
Joined: Sat Dec 13, 2014 6:34 pm

Re: Stair Vignette Riser Height

Postby BAA » Sun Dec 14, 2014 8:01 pm

Not sure if I'm following you guys. I thought the riser height was a fixed constant dimension that can't be changed. Is there a way (ie-controller button) that allows you to adjust the riser ht in the program? Or is it something you have to assume and stick with through out the program?

Example (that would not work with a 7" Riser):
Ground Floor = 0'-0"
Intermediate level = 2'-0"
Upper Level = 16'-0"

You would assume a 4Risers (@6") and then play with your Tread Depths lengths (min. being 11", but 12" is much easier to work with). Beside I believe the Program states the Stringer is 12" so I don't think you can go beyond that.

Anyway let me know if this is doable or if I'm misunderstanding something.
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby crishe3 » Sun Dec 14, 2014 8:21 pm

The risers are not a fixed dimension. They are determined by dividing the change in height divided by the number of risers. I could not use a whole number (6")for a riser.

Example (these are not what I had on the exam):
Ground Floor 0'-0"
Intermediate landing: 1'-8"
Second Floor: 11'-8"
ground floor to intermediate=20"/3risers=6.66" riser height
intermediate to second floor=120"/18 risers= 6.66" riser height

I was asking if I had to keep the 6.66" riser height for the change from 20" AFF to 140" AFF or if I could use 120"/20 risers=6" riser height.
crishe3
 
Posts: 6
Joined: Tue May 21, 2013 8:39 am

Re: Stair Vignette Riser Height

Postby BAA » Sun Dec 14, 2014 8:50 pm

Why did you divide the 20" by 3 and use a fraction like 6.66"? Why not 5 and use a 4" Riser? Code states that the max Riser is 7" and min is 4".

With that said, it seems the heights will always be multiples of 7s, 6s, 5s, or 4s. and should be able to used throughout the program. I have not a seen an example where this doesn't work yet.

Correct me if I'm wrong
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby examslayer » Sun Dec 14, 2014 10:55 pm

It seems like using a 5 inch stair is over building, you'll need a much longer flight versus using a 6 or 7 inch stair, don't you think?
examslayer
 
Posts: 28
Joined: Sat Dec 13, 2014 6:34 pm

Re: Stair Vignette Riser Height

Postby crishe3 » Mon Dec 15, 2014 7:35 am

The 5" stair would not have worked for the space if all the risers needed to be the same height. If I used a 5" riser height from the base to intermediate and a 6" riser from intermediate to the second floor, the vignette would have been much easier. I was not sure about this in the test, therefore I used the same riser height for all the stairs. I had never come across a questions like this before so I did not know what to do in the test. I would still like to find out if anyone knows whether or not all the riser heights have to be the same.
crishe3
 
Posts: 6
Joined: Tue May 21, 2013 8:39 am

Re: Stair Vignette Riser Height

Postby Apollodorus » Tue Dec 16, 2014 2:08 pm

I feel you should be ok.
Last edited by Apollodorus on Sun Jan 04, 2015 1:57 pm, edited 1 time in total.
Apollodorus
 
Posts: 15
Joined: Wed Dec 25, 2013 4:17 pm

Re: Stair Vignette Riser Height

Postby Apollodorus » Wed Dec 17, 2014 11:05 am

Coach, please bless with your thoughts!
Apollodorus
 
Posts: 15
Joined: Wed Dec 25, 2013 4:17 pm

Re: Stair Vignette Riser Height

Postby skip » Wed Dec 17, 2014 2:32 pm

chrishe3, i'm in the same boat. Did exactly what you described, fearing that NCARB's definition of flight may be from floor to floor. Looking at an older post, Coach states that a flight is landing to landing, so modifying the riser height would've been fine. viewtopic.php?t=16276&p=57420

However, I'm hoping that since my layout still meets all of the requirements (albeit not as efficient as possible), it'll still be OK.
skip
 
Posts: 10
Joined: Tue Oct 14, 2014 3:27 pm

Re: Stair Vignette Riser Height

Postby BAA » Wed Dec 17, 2014 6:46 pm

I'd like to some of you guys/gal solutions for Alt 3. The first landing/level is at 3'8" (= 44") and a 7" riser will not work with this problem. I have not found any example that has a riser height were you need to use a fraction of a inch to solve. Unless I'm really missing something fundamental about these problems.
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby examslayer » Thu Dec 18, 2014 9:06 am

I would say you should definitely practice this problem assuming the stairs won't be round numbers. For this reason I would say this vignette is the hardest. There could be a situation where there's no way to make the stairs exactly equal, just close... Since the landing location is going to be constrained with head heights and the only way to set elevations is with a round inch, not fractions... So practice calculating stairs!!
Last edited by examslayer on Thu Dec 18, 2014 9:10 am, edited 1 time in total.
examslayer
 
Posts: 28
Joined: Sat Dec 13, 2014 6:34 pm

Re: Stair Vignette Riser Height

Postby crishe3 » Thu Dec 18, 2014 9:09 am

Thanks Skip. Hopefully, this thread will help someone else out. The vignette would have been a lot easier if I knew that the flights could be different. I was not prepared for any fractional risers, so it took a long time to figure out. I just found out I passed this morning (officially done). I did use all the same riser heights and it took me until the very end. In my opinion, this vignette was the trickiest out of all the exams. Good luck to everyone.
crishe3
 
Posts: 6
Joined: Tue May 21, 2013 8:39 am

Re: Stair Vignette Riser Height

Postby Jer26 » Thu Dec 18, 2014 12:28 pm

Awsome topic guys. i too am concerned about this. I did ALT-3 last night and it took forever. I started out with fractional riser heights all the way up from ground level but the landings only go by the rounded inch. How were you able to set the landings? In the end I had to go with 4" risers from bottom to top so they were all the same at 4". In Alt-3 that is ok but im sure the test would be tighter and would not allow for this
Jer26
 
Posts: 134
Joined: Mon Oct 28, 2013 11:29 am

Re: Stair Vignette Riser Height

Postby skip » Thu Dec 18, 2014 2:04 pm

I stuck with a rounded number the entire way up. By doing so, it made my run longer than it needed to be and as a result, I had to add an extra landing and make the overall stair take up more space. I'll let you know when I receive the results - I'm really curious to how much "efficiency" factors into the grading of the solution. I'm reminded by someone claiming this is a puzzle, not architecture - so I'm optimistic that even if it's not 100% efficient, as long as the requirements are met and it's reasonable, it'll be an acceptable solution.
skip
 
Posts: 10
Joined: Tue Oct 14, 2014 3:27 pm

Re: Stair Vignette Riser Height

Postby BAA » Thu Dec 18, 2014 6:14 pm

Jer26 wrote:Awsome topic guys. i too am concerned about this. I did ALT-3 last night and it took forever. I started out with fractional riser heights all the way up from ground level but the landings only go by the rounded inch. How were you able to set the landings? In the end I had to go with 4" risers from bottom to top so they were all the same at 4". In Alt-3 that is ok but im sure the test would be tighter and would not allow for this


Yes, Alt 3 will work with a 4" Riser (ie. a perfect round number that is code compliant). I'm still looking for a problem that will not work with a perfect 7-6-5-or 4 Riser. I understand the landing may be longer if you use something like a 4" riser, but it should pass.

examslayer, I'll take your advice and try it with these 'round' inches.

Congrats crishe3, I see this is no longer your problem to worry about now ;)
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby Coach » Thu Dec 18, 2014 6:19 pm

A flight is landing to landing.
Riser height may vary between flights.
There's no need for even inches. Why would anyone think so?
The best way to determine the number of risers required per flight is to take delta between landing, divide by 7, and round up.
User avatar
Coach
Site Admin
 
Posts: 13249
Joined: Wed May 23, 2012 2:08 am

Re: Stair Vignette Riser Height

Postby Jer26 » Thu Dec 18, 2014 7:39 pm

Thanks Coach.
Jer26
 
Posts: 134
Joined: Mon Oct 28, 2013 11:29 am

Re: Stair Vignette Riser Height

Postby BAA » Thu Dec 18, 2014 7:54 pm

Coach wrote:
There's no need for even inches. Why would anyone think so?
The best way to determine the number of risers required per flight is to take delta between landing, divide by 7, and round up.


1. Even inches makes for easy math. Why use rounded inches or fractions?

2. Why divide by the number 7?
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby Coach » Fri Dec 19, 2014 1:40 am

BAA wrote:
Coach wrote:
There's no need for even inches. Why would anyone think so?
The best way to determine the number of risers required per flight is to take delta between landing, divide by 7, and round up.


1. Even inches makes for easy math. Why use rounded inches or fractions?

The exact riser height is irrelevant. You should be estimating (or fixing a min based on what's below) what a good intermediate landing height would be and providing risers per above.

2. Why divide by the number 7?

I'll let you think about that for a sec.
User avatar
Coach
Site Admin
 
Posts: 13249
Joined: Wed May 23, 2012 2:08 am

Re: Stair Vignette Riser Height

Postby BAA » Sun Dec 21, 2014 7:10 am

Coach wrote:
BAA wrote:
Coach wrote:
There's no need for even inches. Why would anyone think so?
The best way to determine the number of risers required per flight is to take delta between landing, divide by 7, and round up.


1. Even inches makes for easy math. Why use rounded inches or fractions?

The exact riser height is irrelevant. You should be estimating (or fixing a min based on what's below) what a good intermediate landing height would be and providing risers per above.

2. Why divide by the number 7?

I'll let you think about that for a sec.



I get it! ... (it took a few days, but every flower doesn't bloom in May). Thanks for the advice about fixing landing based on what's below.
BAA
 
Posts: 188
Joined: Mon Oct 13, 2014 1:35 pm

Re: Stair Vignette Riser Height

Postby adam28 » Fri Nov 13, 2015 3:56 pm

Coach wrote:A flight is landing to landing.
Riser height may vary between flights.
There's no need for even inches. Why would anyone think so?
The best way to determine the number of risers required per flight is to take delta between landing, divide by 7, and round up.


Coach, I came across a different one here in terms of the dividing the riser height:

Example (these are not what I had on the exam):
Ground Floor = 0'-0"
Intermediate level = 1'-9" (21")
Upper Level = 12'-0" (144")

In this case, obviously I can't divide them evenly to get a whole number for the riser height all the way up. Assuming the flight is only from landing to landing according to your theory, I could have 3 different riser heights across 2 landings, and this time I do need the difference happen for the flights from intermediate level to upper level. Do you think this solution could work: 1st flight is 3 steps x 7" from 0" to 21", 2nd flight is 9 steps x 7" from 21" to 84", 3rd flight is 10 steps x 6" from 84" to 144"? And regardless of the headroom and the plan layout, could this be the ideal solution for the height division?
adam28
 
Posts: 1
Joined: Fri Nov 13, 2015 3:22 pm

Re: Stair Vignette Riser Height

Postby Coach » Fri Nov 13, 2015 9:30 pm

Ideal is irrelevant. The point is that each flight can have different riser heights and the height doesn't have to be a whole number.
User avatar
Coach
Site Admin
 
Posts: 13249
Joined: Wed May 23, 2012 2:08 am

Re: Stair Vignette Riser Height

Postby TMD_Architecture » Mon Mar 20, 2017 7:16 am

What if you do not use whole numbers, then your landing elevation winds up being a fraction of an inch? The software only allows for whole inches?
TMD_Architecture
 
Posts: 31
Joined: Tue Oct 08, 2013 11:48 am

Re: Stair Vignette Riser Height

Postby Coach » Mon Mar 20, 2017 9:53 am

TMD_Architecture wrote:What if you do not use whole numbers, then your landing elevation winds up being a fraction of an inch? The software only allows for whole inches?

Ugh.
Set landing height. Delta/7, round up.


:brick:
User avatar
Coach
Site Admin
 
Posts: 13249
Joined: Wed May 23, 2012 2:08 am

Re: Stair Vignette Riser Height

Postby TMD_Architecture » Mon Mar 20, 2017 12:31 pm

if a landing calculates to be at elevation 10'-2-1/4" than I should just round up and make the landing at 10'-3"? Once I get to the last landing the elevations may not add up correctly.
TMD_Architecture
 
Posts: 31
Joined: Tue Oct 08, 2013 11:48 am

Re: Stair Vignette Riser Height

Postby Coach » Mon Mar 20, 2017 1:21 pm

You're letting the tail wag the dog.

You first set landing elevation to what you think will work. You can easily estimate it. Then, and only then, do you determine how many risers are required.
The eventual riser height is immaterial as long as it's within allowable range.
User avatar
Coach
Site Admin
 
Posts: 13249
Joined: Wed May 23, 2012 2:08 am

Re: Stair Vignette Riser Height

Postby TMD_Architecture » Tue Mar 21, 2017 9:35 am

Got it Coach!
Thank you!
TMD_Architecture
 
Posts: 31
Joined: Tue Oct 08, 2013 11:48 am


Return to BDCS - BUILDING DESIGN & CONSTRUCTION SYSTEMS

Who is online

Users browsing this forum: No registered users and 46 guests

cron