Weird Revit Railing Stuff - Part 3 - Rail Offsets

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Rail Offsets

Following on from my earlier post (Top Rail Transitions) about the subtle differences between old and new style railings, here is another weird difference.  In my attempts to get the transitions working properly on the inside railing, I played around with the railing offsets in plan at the stair half landing.  Each railing type gave different result - rather than try to explain what is happening, here are the offsets and outcomes for each type in the situation where the risers on a half landing are staggered by one tread (which should be buildable).

Old Style Railing (no top rails)

When the railing sketch exactly follows the edges of the stairs and landing, none of the types work, as we have seen previously.  

So, with the old style railing (no top rail), I first offset the sketch line on the landing by 16mm.

 This was enough to get the transition to the upper run railing section working, but not the lower run.

16mm offset landing sketch line

Section view - 16mm offset landing sketch line

 So then I tried increasing the sketch by 1mm to 17mm, which fixed the lower transition too

 Sadly the mitred joints show in 3D views

17mm offset landing sketch line

Section view - 17mm offset landing sketch line

From the section it can be seen that the transition only works because the 17mm allows the underside of the sloping rail to get to the correct height before the 50mm width of the rail turns the corner (different size rails and different stair angles would need different offset dimensions).

NB. notice how the section view shows old style rails solid in elevation when selected.
 

Top Rail Only - Transition = Simple

16 or 17mm offsets do not work at all for the new top rail type, even though the geometry is exactly the same

Section view - 17mm offset Top rail only

If you increase the offset by another 7mm (to 24mm) it still does not work

In this example it even leaves a gap between the horizontal and upper sloping rail (with corresponding warning message).  There is a mismatch between plan and 3D view.

 However, add another 1mm to the offset (up to 25mm) and it works again

 And it even works in plan

And in 3D it does not show the mitre joints (unlike old style rails)

So it seems that you have to increase the offset in plan by another 8mm to make it work as a Top Rail compared to the old style railings - even though the geometry should work without that 8mm.  WHY the difference?


But it gets worse . . . . .

Top Rail Only - Transition = Simple

Try changing the Top Rail to have "None" transition, and it breaks again - this time leaving a gap between both sloping runs and horizontal landing rail.

At least the broken plan section and 3D view are consistent (unlike the broken rail Simple transition where plan and 3D do not match)

Just add one more mm and it behaves again.  Crazy Huh?

The moral of the tale is that there is no consistency between old and new style railings; nor between different transitions in the new style Top Rails;  and quite often no consistency between plan, section and 3D.  And if you try playing around with these same settings you will most likely get different results to those shown here - because there are so many hidden settings that it is really tricky knowing which change you made does what.  Each time I tried this on a different stair in a different project I got different results.

At worst, I would like to see the new Top Rails achieve successful transitions within the same dimensions as the old railings.  At best I would like to be able to make successful transitions within much tighter constraints as they can actually achieve on site.

Reference:
Top Rail Properties in Revit Railings
Weird Stuff in Railings - part 1 - Top Rail Transitions
Weird Stuff in Railings - part 2 - Railing Extents 

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Top Rails in Revit Railings

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Revit 2013 introduced a whole new way of building stairs.  At the same time some subtle changes were made to railings in Revit - in particular the new concept of a "Top Rail" as a separate sub-component of the railing definition.  This can cause confusion as the old rail structure still remains in Revit, and the two methods can sometimes perform the same function - but with different behaviour. . . . . .

The railings type properties dialog boxes have always been complex (particularly balusters, but that is another matter).

• Old style horizontal rails in a railing family:

• Horizontal Rail Structure in old style railings:

• From Revit 2013 new properties were added:  "Top Rail", "Handrail 1" and "Handrail 2".  For the moment we are only interested in the Top Rail, which can do the same job as the highest rail (old style), including controlling baluster heights.  Even if you upgrade an old project (or template) you may not see the new properties on old railings - you have to swap them over for new railing types that are supplied in the new project templates (and then match all the other settings you want).

• Top Rail properties in a Railing only have two settings - a height and a Type.  By default the type is set to "None", which means you won't get anything.

• You have to select from a drop down menu to get a predefined top rail type.  You cannot change the properties of the top rail here.

• It is the same old three-step trick in Revit:  close the dialog box, go to the Project Browser, find the new "Top Rail Type" system family (subset of Railings category) - modify, duplicate, rename etc.  It will have some interesting new properties - the most important being "Profile" where you can select a 2d profile family (another 3 steps to change that if you need to!);  other interesting properties include Extensions and Terminations, but that is for another time.

• One other important property is "Transitions", which controls how the top rail behaves at changes of angle in the rail.  What this does will be demonstrated in the next blog post.

The new Top Rail and old Rail structure can coexist, or you can have one or the other;  you cannot have neither though, as the railing must have at least one horizontal component.  Depending on which combination you have, Revit will give quite different results, and can display some weird behaviour - to be described in following blog posts:

• Weird Stuff in Railings - part 1 - Top Rail Transitions
• Weird Stuff in Railings - part 2 - Railing Extents

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Revit Multistorey Railings - Story 1

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[Edit: Revit 2018 has a new method for creating multistorey stairs & railings, so the issues described here will not be relevant once you upgrade to v2018;  if you are using v2017 or earlier, read on]

Here is a curious story to tell:  This is a description of how to manage railings on a multistorey stair that has been created using the "Multistory Top Level" stair property in Revit (Method 1 in my previous post), and where you have incorporated intermediate landings on each building level of the stair.  The resulting railing will be a single closed loop - both inside and outside joined together. 

The description below assumes that you followed the steps in the previous blog post  to get to this stage.  If your multistorey stair does not include landings at the storey levels (maybe you used floor slabs instead), none of this applies.

Edit Railing
If you try to edit the railing to get rid of the section running across the landing/run junction or the outside edge of the landing, you will run into problems in Railing edit mode

After you delete the unwanted lines and then finish the sketch it will give an error message – it requires a single continuous chain of sketch lines, not a loop within a loop (even if you remove all overlapping lines)

To solve this the railing needs to be first separated into two parts. This can be done by two different methods:
1.  You could duplicate the single railing and then edit each one separately, stripping them back to an inner and an outer railing (Process not described here).
2.  Alternatively, take a few steps back in the stair creation process, to edit the railings before you delete the temporary top flight:

• first you need to do some undoing to reinstate that temporary run above the top landing (refer Method 1 or item 5 of Adding Landings to top of stairs );  

• Edit the outside railing (because of the top run there are two separate railings). 
• Delete the segment associated with the extra run

• Make sure there is a break in the loop by dragging the end of the landing rail line away from the first run line; the gap must be at least 32mm otherwise the lines will automatically rejoin! (That is about 1 ¼ inches in that quaint imperial system used in the USA).

• NB. If you want the sloping section of rail to extend one tread beyond the lowest riser (common practise), then you need to extend that line by one tread depth before making the 32mm gap.  It may give you a slope warning, but it is not clear why because the railing will be parallel to the flight

• One method to stop that warning is to make the sketch line overrun dimension just short of a tread depth – by 1mm say (for a 250mm tread, the railing sketch line should extend 249mm past the lowest riser)

• Then you need to do something similar for the inside loop railing – delete unwanted segments and make a gap. You might again want to extend the sloping rail line by one tread (minus 1mm), and then make the gap in the short landing line

• Another alternative is to extend the short landing line by at least 32mm, and leave a gap of 1mm to avoid the sloping railing warning. The best option depends on how your rail is defined relative to the sketch line location and how you want the join to work

• Finish the railing sketch

• Edit the stair to delete the top flight – the railings should now be separate. NB. This process does break the automatic nature of the railing sketch – it will no longer update when the stair changes

Once you make the stair multistorey again, the railings should behave better. The small gaps may not be perfect but they are a whole lot better than the junctions that Revit makes normally

If you don’t want the railings to run across the back of the stair landings (eg. doors onto landing), you can edit the railing to remove segments but you'll lose the side railing of the landing (because you need a continuous chain of sketch lines in the railing)

Then you need to add a new railing to the landing sides: host it on the stair if you want it to be the same on both levels (it will become multistorey if the stair is); or host it by level if you want different railings on each landing

 

Watch out for the “Tread/Stringer Offset property for the railing so that it will align properly with the other railings (defaults are different for automatic railings and manually created railings)

Non-multistorey railings must be hosted by level, not on the stair – that way they can be different on each level

However, if you find all this is too fiddly, or else you need the top landing to be different then you may need to try Method 2 for multistorey stairs.
You could also lobby Autodesk to fix the railing tool so that it works better with the new stair by component tool!  Maybe one day we won't have to invent these horrible clunky workarounds.

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