Staircase design is one of the most understated components of the building, being one of the most common form of vertical circulation.
The main purpose of staircases is to bring visitors from one level to another.
As architectural designers, we should understand that well-designed staircases are not only aesthetically pleasing, they have to be also functional.
Types of Staircases
The following are key terms and definitions you should know while designing staircases:
Tread - Horizontal portion of the step
Riser - Vertical portion of the step
Tread depth - Horizontal distance for each step
Riser Height - Vertical distance for each step
Landing - Flat platform at the beginning, between or at the end of staircase flights
Flight - A series of steps between landings
Handrail - Barrier / support bars along staircases
Stringer/Support - Kerb supporting balustrades along staircases
Nosing - Edge of steps
Pitch - Diagonal line joining the nosing of each step
Clear width - Effective distance between handrail without any obstruction
Headroom - Effective distance from pitch of staircase to any obstruction vertically above.
Types of Staircases
The above diagram shows the various types of staircases we have at our disposal.
Each of these staircase types have different footprints, constraints and use cases.
The main thing to consider while selecting what type to use is the spatial constraints - details below.
Constraints & Dimensions
The main spatial considerations are length/footprint, height and headroom constraints.
Generally, when designing staircases, you need to do the following:
- Obtain the floor-to-floor height and calculate effective staircase height (see Drops below)
- Establish your desired riser height and number of risers using my online calculator
- Once you know how many risers you need, establish your tread depth and starting calculating the space you need to fit you steps and landings, starting by multiplying the number of treads by the tread depth
- Number of treads = Number of risers -1
- Establish your clear width (usually above 1m) and landing distances.
- Start to draw out the rough footprint of the staircase
- Cater for the supports/handrails (usually 100mm thick on both sides of flight)
- Cater for gaps for U-turn staircases (usually 100mm between supports)
- Cater for handrail extensions (usually 300mm - see your country building codes)
- Check for headroom issues
One good detail is to place drops and kerbs to control the flow of water from washing.
Typically, we will want water not to flow from the corridors from upper storeys into staircases. If it happens we get unwanted waterfalls. Thus, we usually place a step up of 50mm to 150mm. Do note that this needs to catered for when we calculate our effective staircase height.
However, we also need to consider the occasions when the occupants need to wash the staircase floors.
In this case, we do not put a step up on the bottom landing as we want water to flow out of the staircase.
No staircase should ever be built without building approval.
Here is a brief overview of the various building code requirements that you need to be aware of:
- Building Regulations
- Tread Depth
- Riser Height
- Maximum number of steps per flight
- Clear width of staircase
- Handrail extensions
- Headroom clearance
- Barrier design (height of railing, toehold, edge protection)
- Accessibility requirements (tapered steps)
- Buildability Score requirements
- Fire Code
- Clear width vs exit capacity
- Means of escape, number/position of staircases along escape paths
- Fire protection / fire-rated walls
- External vs internal exit staircases
- Door swings (should not interfere with escape path along staircases)
Here are some other tips and tricks for staircase design:
- Best Practices for Tread Depth and Riser Height
- Public spaces - 300TD, 150RH
- Residential, Commercial, Institutional - 275TD, 175RH
- Industrial - 250TD, 175RH
- Staircase Materials
- Preassembled Steel Staircase
- Addressing Buildability Score Requirements
- Use standard dimensions
- Standardise floor-to-floor heights