by Dennis Collin
Railings and stairs are typical areas of Revit which users tend to get frustrated with. They are complex families that are a guaranteed occurrence within most Revit models. Stairs need to adhere to codes and have requirements for minimum egress widths etc. If the working area is tight, the railings created by default get in the way visually and often are not correct in terms of what’s required.
So, the first tip of this blog is not to model them at the same time as creating stairs! If they have been created, just delete them! The stairs and the stairwell space will dictate the position, type and nature of the railings anyway! By making the stair clearer to see and diagnose, it will make the modelling process far easier to understand the problem and what to do to fix it. The railings can always be added in and modified later once the stairs are correct.
Fig 1. By default, railings rarely provide what the user wants!
When creating stairs, by default Revit will provide a sample railing system for free! Nice though this sounds, this generally is not desired because as mentioned before the railings are often incorrect and just get in the way.
It is possible to tell Revit just to provide stairs and create no railings by choosing the ‘none’ option in the railing option of the stair creation command.
Fig 2. Toggling off the automatic creation of railings is not as silly as it sounds!
For half and quarter landing types of stair, railings can exhibit strange behaviours where there is an excessive change in height, resulting in broken contious rails, odd stepping or undesired error messages. In Figure 1, we see a typical behaviour of a typical stair and its railing partner.
What is probably more desired is something like the image below, where the hand rail is more continuous in nature and has a smoother transition between stair flights.
Fig 3. Whilst not at fabrication detail this stair at least shows clearly the design intent!
To get to this ideal situation it is easier to delete the railing and resolve the more important element the stair itself!
Railings are effectively defined by sweeping a cross-sectional profile along the route of the stair path which is a different height throughout. Where there are extreme changes in heights in a short distance is the root of the trouble as the railing family does not have enough room to ‘make the bend’ and form clean geometry.
In this instance, a landing extension (1) can be applied to the flight and an adequate width between the two flights (2) ensures that there is enough distance for the railing to keep up with the stair!
Fig 4. For Half or Quarter landing stairs it may be necessary to make some room for railing transitions!
In addition to the landing extension, ensure there is an adequate gap between the two flights any values of course must be in accordance with local stair regulations. But once complete, finish the stair sketch and ensure it fits with neighbouring walls etc. and that no erroneous geometry is apparent.
Fig 5. A stair with clean geometry with no railings in the way and confusing the issue!
Assuming all is well, a suitable railing system can be created (or reinstated) by using the create railing tool. Although railings can be sketched, a better method may be to select a stair and choose a suitable hosting method. Either treads or stringer can be selected depending upon the railing type and the required clearance width. The chosen option will then deform the railing according to the stair geometry and a reasonable result is usually obtained.
Fig 6. Railings can be easily placed, once users are happy with the stair arrangement!
If railing stepping or still occurs there is also a landing height adjustment setting within type properties which provides a little extra adjustment for railings between stair flights and landings.
Fig 7. Landing height adjustments are also useful for more accurate railing behaviour.
With a mix of these approaches by modelling stairs, allowing for offsets whilst still complying with standards, most simple railing placements work as expected.
Of course, depending upon where the stair is, is it open or enclosed by walls, interior or exterior edge, extensions and different railing types do complicate matters. Whilst at first glance it looks like these tasks can’t be done, there are a few tricks that can be utilised so that even presenting design intent for complex stairs is not too arduous a task. But again, get the stair modelling right, the railings will generally be fine too, although for some bespoke arrangements such as winders this will require using Revit’s sketch tools and in places, adjusting sketch line sloping behaviours. These tricks I will cover in a future post. I will also show some workflows where different behaviours are required for handrails, guard rails and where necessary make these elements non continuous!
Fig 8. Using these tricks stairs with winders on a point make it difficult, but, not impossible to get an acceptable result!
A final word on stairs and railings, they are not intended to be modelled to fabrication level. I would say these tools are just enough to show the design intent. When getting down to the detail and production documentation stages, users should use detail components, tools and callout views for those fine scales.
In summary, stair and railing families are some of the more complex Revit families, with settings and controls that are several levels deep in terms of dialogue boxes. Stair and Railing elements are a popular topic of discussion on Cadline’s follow-on and bespoke training courses. For more details visit https://training.cadline.co.uk/ and talk to one of the team who can help you with your requirements.
Opmerkingen (0 opmerkingen)