SIA 358, the Swiss norm for railings and parapets, is one of the most human documents on a detailer’s shelf. Its numbers are measured against bodies: a railing top at least 1.00 m above the floor and, where small children are expected, no opening a 12 cm sphere can pass through. On Wednesday, 30 September 2026, we give it a whole Archicad Powersession, because a norm this close to people deserves to live inside the model. It should not depend on someone’s memory and a scale ruler at the end of the job.

Norms like this do not write themselves. SIA standards come out of commissions of practising engineers and architects, much of it carried in the Swiss militia tradition. The bfu, the Swiss Council for Accident Prevention, has long turned the railing rules into guidance a site can actually use. Their names are rarely on the drawings they shape, yet every safe balcony in this country carries a little of their work.

What changed on our side is the tool. Since Archicad 21 brought the Stair and Railing tools in 2017, a railing has been a rule-driven element rather than a bundle of lines, with posts, rails, balusters and panels each following their own logic. Add properties, GDL and the Python API, and a norm can be expressed right where the geometry is made.

PAZ has walked this ground before. According to our ARCHICAD Bootcamp programme, automation in Archicad happens in four places, PARAM-O, Grasshopper, GDL and Python, and the Bootcamp worked through them in three 30-minute live sessions and a one-hour masterclass. Our free 25-day introductory course, as the PAZ Freebies page describes it, walks the same ground from Rhino and Grasshopper through the Archicad Connection. This Powersession asks what that map looks like when the brief is one Swiss norm.

Practitioners are already pulling the pieces together. According to a recent Graphisoft Community thread on CI Tools Keynotes and Archicad’s own properties and attributes, these are “individually valuable improvements” that now need “a little refinement” to come together as a cohesive whole. Fall protection is a good place to do that joining. It comes down to a height, a gap, and whether a child could climb it, and the model should be able to answer yes or no on its own.

←TODAY: In 2026 a railing in Archicad is a smart element, yet whether it meets SIA 358 is still often answered by eye.
→3012: In Zurich-3012 every railing knows the norm it was drawn to, and the plan check reads like a conversation.
Fulcrum: A norm encoded once stops being policed and starts being designed with, and that is where the hours come back.

Who it is for: Archicad users in Swiss offices who draw balconies, galleries, stairs and low-sill windows week in, week out. It also suits BIM coordinators who own the office template and its railing favourites, and the GDL-curious who want a first real object with a norm behind it. Date, format and registration sit on our session page.

One trade-off belongs on the table from the start: a norm encoded in a library object is only as current as the person who maintains it. Freeze the parameters, and you freeze one edition of SIA 358 into every project that follows.

Hack: Let the balusters count themselves, so no clear gap in a custom railing object can ever pass 12 cm.

n = CEIL((A - bw) / (0.12 + bw))   ! fewest bays that keep every gap at or under 12 cm
gap = (A - (n + 1) * bw) / n
FOR i = 0 TO n
  ADD i * (bw + gap), 0, 0 : BLOCK bw, bw, 1.0 : DEL 1
NEXT i

Here A is the object’s length and bw the baluster width, both in metres. n is the smallest number of bays that holds the limit, and the remaining length is shared evenly between the gaps. If you stretch the railing in plan, the count re-solves and the spacing never grows past the norm. It takes a few lines of GDL, and afterwards the object keeps the rule for you.

Atelier: For an office adopting AI assistants, fall protection is a useful test of honesty. An assistant can only answer “does this railing comply?” if the railing carries its height and gap as data; a railing drawn as lines gives the machine nothing to read and the human nothing to trust. Monday move: open your office template, list every railing and parapet favourite, and mark which ones state their SIA 358 height and maximum clear gap as properties. The unmarked ones are the next thing your team fixes.

From where we write, decades on, the offices that aged well were rarely the ones with the most scripts. They were the ones where the person who knew the norm and the person who built the object sat at the same table. Before Wednesday, open one railing in your current project, measure its widest clear gap, and bring that number with you.