Stairsmith

1 Introduction
2 Background
3 Staircase types
4 How it works
5 Exports
6 Limitations
7 Technology
8 Related articles on Designing Buildings
9 External links

[edit] Introduction

StairSmith is a free staircase design tool. It is open-source and browser-based, offering architects, architectural technologists and designers parametric 3D modelling of residential timber staircases, with export to IFC 4.3 (IFC4X3) models and dimensioned DXF drawings. As an online tool it runs in any modern web browser and requires no installation, no login and no server-side processing.

[edit] Background

Staircase design in residential projects typically involves iterative adjustment of rise, going, pitch and width to suit a specific floor-to-floor height and available plan area. Traditionally this is done manually in CAD or by calculation, with the 3D model and 2D documentation produced separately. StairSmith combines the parametric input, 3D visualisation and file export into a single browser-based workflow. It is intended for designing and documenting a domestic staircase quickly during design and technical work, for example in a new dwelling, an extension or a loft conversion, including quarter-turn, half-turn and half-landing arrangements that simpler stair calculators do not typically produce.

The tool was developed by Jake White Architecture, a residential focused architectural practice based in West Sussex. The concept grew out of a discussion within the Architectural Technologist Power Team (ATPT), a peer group of Chartered Architectural Technologists.

[edit] Staircase types

StairSmith supports four staircase layouts:

Straight flights
90-degree single winder turns (quarter-turn staircases)
180-degree double winder turns (half-turn staircases)
Half landing (U shaped)

Winder staircases use traditional kite winder setting-out geometry. The modelled components include treads, risers, newel posts, stringers, handrails, baserails and spindles.

[edit] How it works

The user enters parameters such as floor-to-floor height, stair width, number of treads and component dimensions. The tool calculates the geometry and displays a live 3D preview that updates as values change. Reference values for rise, going and pitch are displayed to assist the designer, but no compliance checking is performed by the tool itself.

All computation runs in the browser. The geometry engine is written in Python, executed client-side via Pyodide (CPython compiled to WebAssembly). The 3D preview uses Three.js. 2D geometry for DXF sections, elevations and winder setting-out uses Shapely, a computational geometry library built on GEOS.

[edit] Exports

StairSmith produces two export formats:

IFC 4.3 (IFC4X3): a structured spatial model containing project, site, building, storey and stair entities (IfcStair and IfcStairFlight), with materials, property sets, stable GUIDs and Uniclass 2015 classification. The file can be opened in any IFC-compatible BIM viewer or authoring tool for coordination with the wider building model.
DXF: a dimensioned drawing set containing a plan view, four elevations and stepped section cuts, suitable for import into CAD software.

[edit] Limitations

StairSmith is a design aid. It does not check or assure compliance with Building Regulations Approved Document K or any other standard. It will model a staircase regardless of whether the dimensions are compliant, and all outputs must be independently verified by a competent person before use.

The tool is designed for domestic-scale timber staircases. It does not currently support concrete, steel or helical staircase types.

[edit] Technology

StairSmith is a fully static site with no backend server. The same Python modules that produce the live 3D preview also generate the DXF and IFC exports, ensuring consistency between what is shown on screen and what is exported.

The source code is published under the Apache License 2.0 on GitHub.

--JakePWhite 21:50, 28 Jul 2026 (BST)