A common building component young architectural designers like yourself need to be able to specify and detail is railings.
Railing are possibly one of the first few things you will come across so it is essential for you to be familiar with them.
So if you are not familiar with railing design, you're at the right place.
In this post, we will discuss what railings are and how to design them.
- What are railings for?
- Components of Railings
- Dimensions and Specifications
- Examples/Case Studies
- Pro Tips
Do note that the recommendations below are based on the building codes from Singapore where I am based in. So please consult your senior to point you to the relevant documents for railing design for approval.
What are railings for?
A railing is a barrier system formed of posts, balusters, and rails.
Railings are placed typically along edges of corridors, staircases and open spaces with an adjacent drop of more than a step height (175mm) to prevent entry and/or fall from height.
They can also be used to separate & divide spaces, or to guide circulation (ie. in queues/transit areas).
A general rule of thumb for architects is to provide railings as a safety barrier to areas with adjacent level differences of more than 1 meter. But architects can choose to provide for all drops as neccessary. (ie. 500mm and above).
This is required and will be checked by the building authorities during plan submission and before granting occupation approval.
A baluster is a short and decorative post, pillar, or column in a series that supports the top rail.
A post is a vertical structure that supports a railing, and it is one of the most critical parts of a railing system. Without posts, the railing would lack strength.
A rail is a horizontal bar, typically fixed on posts, that forms the top or bottom section of a railing. The rail acts as a guard or barrier.
Note the railing extends 300mm outwards at the start and end of staircases. This is a building authority requirement in Singapore where this provides adequate tactile notice that the staircase has ended.
Dimensions & Specifications
The following are things to note and specify in your railing design:
- Length of barrier (start, end and Height of barrier (typically min 1000mm)
- Balusters spacing, number of balusters between posts, profile of baluster
- Profile of posts
- Patterns of balusters
- Height of rails from the ground (top/bottom)
- Position of toehold (last, highest climbable railing segment)
- Panel design if replacing balusters
(ie. Materials, Thickness - glass, aluminium, perforations)
- Edge protection
- Fixing detail to RC kerb
- Maximum opening size as per building code requirements (depending on function of the space the railings are placed in)
Height of railing
The first thing is for railing design is to ensure a minimum of 1m barrier height from the finished floor level to the top of rail.
You can specify for 1m high railing in your architectural drawings and request for shop drawings where the supplier will detail the section of the railing, similiar to what to see below.
One important thing to note the placement of the uppermost toehold, which cannot be less than 850mm from the top of barrier.
According to the Building & Construction Authority in Singapore Approved Document, a toehold is defined as any opening in a perforated sheet or mesh having a horizontal dimension of more than 50mm and a vertical dimension of more than 30mm; or a kerb or protrusion having a width of more than 50mm and has a chamfer gentler than 45 relative to the horizontal plane.
Thus, for a 1m high barrier, you should specify that the last toehold is to be maximum 150mm above finished floor level.
Requirements for handrails:
For handrails, the typical acceptable profile of rail to be (32-50mm minimum diameter). This ensures the sizing of the handrail enable proper and safe grip by users.
In addition, for handrails (including recessed handrails), the distance from wall shall be at least 40mm for smooth walls and 60mm for rough wall from the handrail to the wall surface. This ensure that the user hand do not get abrasion while using the handrails if the wall surfaces are too close.
A general rule of thumb is to provide at most 100mm spacing between the balustrades (or vertical secondary rails).
This ensure the safe use of railings by ensuring no body part can be 'accidentally' stuck (eg. arms, legs).
The spacing requirement also depends on the function of the area - it can be 500mm apart at maintenance areas.
Lastly, you need to also ensure proper edge protection.
This means that the lowermost part of the railing is to be either provided with a horizontal bar at most 75mm above the finished floor level (FFL).
Alternatively, you can also specify a kerb of 75mm from FFL throughout thewhole railing length.
How to model railings in Revit
The below graphic shows how to create a railing in Autodesk Revit. Most BIM software will generate railings based on a sketch (or path) - bascially the 2D plan of the center line of the railing.
If you're keen on learning more on how to configure railings, I highly recommend Revit Pure's post on railings in Revit.
The following images show how I have observed railing design can differ and allow for creativity and reinterpretation while complying with all of the building authority requirements.
Material - Perforated Panels & Weld Mesh
Panels can replace balusters between posts and can vary in material, transparency and patterns, while wire weld mesh can be used along the entire the railing design.
Note the height of these panels/mesh and relate to the requirement of the last climbable toehold.
Balusters can reimagined to become design elements in the built environment.
Apart from their intended functions, they can be reinterpreted to become wall features.
Landscaping and lighting features can also be integrated in the railing system.
Railing design for special uses
The design of railings really depend on the type of use.
Here you see Railings sections can be designed to be removable for the loading of equipment
(eg. at the upper level of an electrical substation)
Wheelchair accessible ramps
300mm long handrail extensions at the start and end of railings are designed to provide ease of transition between levels.
Also notice how the spacing of the balusters are allowed to be far apart - this is because there is no level difference beside the ramp.
An easy way to understand railings is to understand its purpose, its components and how to specify them.
The main consideration is to prevent fall from height required by building code as well as to allow it to blend well with the overall design.
The height of the barrier is one critical dimension to state in the architectural specifications, with the top rail typically 1000mm above FFL.
Other things to note include edge protection, gaps between balustrades/panel design and 300mm handrail extensions along staircase railing.
I hope you have enjoyed learning about railing design in this post.
If you liked this post, do share this with someone starting out in the industry!