Stair mid-landing height

[Adam Mac]

Hi all....

Is there a way to "fix" the height of a stair landing on an "L" or "U" shaped
stair?

I have a situation where the mid-landing needs to be at a certain floor level
and can't see any way of ensuring that the landing occurs at this level.

OR do i have to use 2 separate stairs? If so - what's the best way to create the landing
and lock it into the stair?

TIA,

Adam

[Mr Spot]

If the risers heights are going to vary between the two flights then you will need to create as two separate stairs.

We typically use floors for the landing with a custom slab edge to make it look as though the stairs join the landing.

[Adam Mac]

If the risers heights are going to vary between the two flights then you will need to create as two separate stairs.


Thanks Mr. Spot - although reading your post makes me realise that i can't have varying riser heights between the two filghts (....duh), but why then can't i get the landing height to be
at 1500 affl when the stair goes from FFL to 1st floor (3000 affl)?

I have offset the base -100 affl. so i'm not sure if this effects the actual stair height.

Am i missing something?

[Steve_Stafford]

Your landing depends on how many risers you are using, no? 3m floor to floor @ 18 risers is 166.667 per riser, 9 risers per run. This puts a landing at very close to 1.5m right? You should be able to hit 1.5m exactly if you go with 150mm risers, 10 risers per run...If you've offset the stair down by 100mm you've got an unequal situation that will move your landing down below slightly...

[beegee]

Using a 100 mm base offset will definitely throw your landing off the mid height.

Revit calculates (3000mm - 100 mm )/ 16 risers = 181.3 mm, therefore the landing height ( for equal flights ) will be 1550.4 mm. You can play around with different unequal flights, but the only way to achieve a 1500 mm landing height in this case is to use two different flights having different riser heights with a landing floor as discussed by Mr Spot.
For a zero base off-set - it works. 3000 mm / 16 risers = 187.5 mm riser ht x 8 risers = 1500 mm landing height.


>>but why then can't i get the landing height to be
at 1500 affl when the stair goes from FFL to 1st floor (3000 affl)?

I have offset the base -100 affl. so i'm not sure if this effects the actual stair height.

Am i missing something?

[Adam Mac]

Thanks for all the replies - if i want a nice "clean" elevation (height) for the mid-landing height then i need to use 2 different flights - fair enough.

Thanks again for the input guys!

[Steve_Stafford]

...if i want a nice "clean" elevation (height) for the mid-landing height...Just to be contrary... Will anyone notice that a landing isn't at 1.5m exactly while they walk up the stair? Nothing wrong with trying to lay things out with nice numbers...but building stairs to code usually means you get some "funny" numbers somewhere. A "clean" landing means the risers get em. Most codes I've been subjected to don't allow different riser heights in the same run of stairs either.

[Adam Mac]

I know what you're saying Steve, but i'm actually more concerned with the level of the floorr that the landing services being a nice "clean" number rather than the stair itself. I wouldn't normally be concerned at all with the landing height if the mid-landing was not connecting to anything.

[beegee]

If the landing is actually a floor, wouldn't you just run a straight flight up from the lower floor to that floor and then another straight flight from that floor to the next level ?

No need for an L or U shaped stair, as such then.....

[artitech]

Off topic (Revit) a moment, but the point about the riser heights and code issues....

The way that I have interpreted this part of the code is that the "run" of stairs can be between landings. You can change the rise on the subsequent flight (run) to the next landing or floor level.

We had an interesting debate on one job whether we needed to check riser heights between flights to see if they were uniform... the code requires a "uniform rise and run", what is the margin for error?

Told you it was off topic, but wondered if anyone interprets the code differently on this issue...?

[bclarch]

The way that I have interpreted this part of the code is that the "run" of stairs can be between landings. You can change the rise on the subsequent flight (run) to the next landing or floor level.This is correct and makes sense if you think it through. When you are going up or down a flight of stairs you quickly establish a rythmic stride to match the stair configuration. If a tread or riser doesn't match the others it will be out of synch with your rythmic stride and you might catch the edge of the step and trip. On the other hand, when you hit a landing, your stride is interrupted. Once you start going up or down the next run you will automatically establish a new rythm matching the configuration of that particular run of stairs.
what is the margin for error?Depends on the code that you use. Sometimes you need to check the reference standards cited in the code.

[Paul Monsef]

Off topic (Revit) a moment, but the point about the riser heights and code issues....

The way that I have interpreted this part of the code is that the "run" of stairs can be between landings. You can change the rise on the subsequent flight (run) to the next landing or floor level.

We had an interesting debate on one job whether we needed to check riser heights between flights to see if they were uniform... the code requires a "uniform rise and run", what is the margin for error?

Told you it was off topic, but wondered if anyone interprets the code differently on this issue...?
Someone in our office had a discussion about this topic down at the good 'ole 'city of Seattle' a short while back... They kinda comfirmed what we already thought (2003 IBC):
1. "The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch"
2. A "flight of stairs" is the run between floors or landings (even an intermediate one).

So I guess you could have one run with risers at 6.5" + a landing + a run with risers at 7" - if you want (but try running up 'em). ;o)

[beegee]

Over here, the BCA ( Building Code of Australia ) requires risers and treads to be constant throughout in one flight. A flight is defined as " that part of a stairway that has a continuous series of risers, including risers of winders, not interrupted by a landing or floor. "

[Adam Mac]

If the landing is actually a floor, wouldn't you just run a straight flight up from the lower floor to that floor and then another straight flight from that floor to the next level ?


Hmmmm.... good point Bee Gee. Could be the case here - it's sort-off a mezzanine i suppose.

I also note the point about the risers - thanks.