by Dennis Collin
Modelling stairs to a specific criterion is a common question when talking to architectural and structural users. Specifically, in getting stairs to connect properly to slabs both at the bottom and the top of a stair component.
The main challenge for users is to get the stair object to finish at the slab level, rather than letting the slab become the final tread. This could be achieved by creating a special in-place family, sketching in a landing, or even embellishing the section with detail components, none of which are ideal solutions.
Fig 1. What we want to see!
The default settings in stairs do not lend themselves very well in connecting to slabs with the default settings. However, a few other options are available which give better results than the former image above. Firstly, connecting a stair flight to a slab at the top of a stair.
Fig 2. For the top connection, better results are often achieved by turning off end with riser.
Best practice to achieve this is to simply turn off the end with riser option when working with the stair flight. In the example shown, the Cast-in-place Stair, Insitu Concrete_150mm_Waist is used, but the principle is identical for any stair family.
Fig 3. The Join function can be used to tidy elements if required.
When drawing the stair, the final step will be in line with the slab. To form a clean cut, the Stair can be joined to the slab and elements will clean accordingly. For greatest flexibility, convert the stair run component into a sketch-based item and adjust the linework so that there is no stepping between the underside of the stair and the slab. Reference planes can be used to coordinate where the diagonal slope intersects the underside of the slab.
Fig 4. In certain situations, convert the run to sketched based linework.
For the stair slab connection at the base of a stair, select and edit the stair family and choose the run element. Set a negative offset for the Extend Below Riser Base property. This should be the same as the width of the target floor slab.
Fig 5. Adjust run properties to ensure a clean connection at the stair base.
Click apply and note that the stair bottom adjusts to the lower slab.
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.
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