In common usage, “stairs” and “steps” are interchangeable terms, but in the precast concrete industry, they are actually two different products and two different applications. When ordering the products, you might find yourself in the wrong order for your entryway, parking area or landscape project. What really differentiates them, and what to look for prior to ordering.
Stairs versus Steps: The Real Difference, Not the Semantic One
This needs to be explained beforehand because it dictates so much of the purchase. Precast concrete stairs and precast concrete steps are two different terms with close connection to each other and depending on the requirements of the project. Precast concrete stairs are used for multi-level access and larger scale applications, such as when the application is a building or parking structure, or any place where there is a need for a lot of vertical movement between levels.
Precast concrete steps, on the other hand, are smaller, individual steps, often a limited access step and are often used for entranceways, patios, decks, etc. If you are dealing with a project that requires you to bring more than one floor together in a building, you’re most probably in stair system land. When you’re considering a driveway to front door connection that is both functional and attractive, precast steps are the only option you’ll likely still be considering.
Standard Sizing for Precast Steps
There are generally accepted industry sizing conventions for precast step units although there is some variation in sizing by manufacturer. Common widths are between about 4 and 10 feet wide, and most common riser counts per unit are between 1 and 7, providing flexibility to meet most residential and light commercial entryway applications without having to design a unit from scratch.
There is also a fairly standard convention of riser height within the industry. Typical precast steps have a 7 inch or 7.5 inch rise; steps can be combined with different rises to achieve the total rise necessary for a particular entry or grade change, or units can be side by side where a wider step is required for the application.
Why Hollow, One-Piece Construction Matters More Than It Sounds
One aspect that can be overlooked but that does have an impact on long-term performance is that precast steps are often formed as one piece, with the tread, riser, and landing all cast in one single piece, as opposed to being formed as separate steps stacked upon each other. This is important for two reasons. The lighter weight of hollow units also reduces the risk of uneven loading over time when compared to a solid mass that is placed on an uneven ground surface; the single-piece casting of the tread, riser and landing reduces the number of connection points that may separate or crack over time.
If the building is outdoors where years of service and ground movement and settlement are realistic, ask your supplier if they use a hollow one-piece construction in their standard steps.
All Details for the Standard Sizing for Multi-Level Precast Stair Systems Are Contained on This Page
Stair systems used for unrestricted access from floor to floor are based on standards different from those used in other stair systems, and are centered on code compliance and uniform step dimensions over a complete flight. These are common specifications, stair units up to 5 feet wide; risers to be around 6.25 to 7 inches; and treads to be commonly 11 inches, which are selected because they fall within recognized building code comfort and safety parameters.
Longer runs can be achieved as well. Some manufacturers can create stairs up to 22 risers in a single run, and this is not because the exact length of the riser, run and flight of stairs is made in a single generic template, but rather each of the projects is engineered in its entirety with no preparation or mistake. This is important because a stair system really does need to be designed to the actual height between the floors of your building, not an approximation from a catalog default.
Standards for Concrete Strength and Manufacturing Properties
Precast stair and step products are normally produced at significantly greater strength than normal structural concrete, due to the many impacts and foot traffic loading that they must encounter over decades. Typical strengths for precast products range from 4,000 to 9,000 psi, depending on the project specification, and provide the flexibility to match the strength with the type of loading and use.
Specific to structural building stair systems, recognised industry guidance is that these should adhere to tolerances defined in PCI MNL-116 and PCI MNL-135, which relate to dimensional accuracy, bowing and warping limits of precast concrete products in general. If fit of your stairs to an existing stair structural frame is of importance, check with your supplier to see if their stairs are PCI certified or made to equivalent recognised tolerances.
Adding Reinforcement to the Hardware, and Handling Hardware
As with most precast structural components, stairs and steps require the right embedded hardware to withstand transportation and installation without damage. Recognized Specifications dictate the placement and securing of all anchors, clips, stud bolts, inserts, lifting devices, and shear ties into the forms during casting so that they are all installed when the casting is placed and secured to surrounding structure for safe handling and eventual attachment.
Exposed edges are given further consideration; the quality specification requires that the edges and surfaces be sharp and straight and square; if these features are not in keeping with a true plane, visible irregularities will constitute a cosmetic defect and a real hazard to anyone who uses the stairs on a regular basis.
Closed Risers and Safety Considerations
Closed risers in stair systems are where the vertical face between the treads is solid (not open) which helps to create a safe pedestrian environment by eliminating gaps that could catch a foot or create a fall hazard. This is something that is important especially for any commercial or public access application, where code compliance and liability could be real issues, and not just residential applications where preference might differ.
Finish & Customization Options
Stair systems and single steps are both truly flexible in terms of their look. Manufacturers are often able to provide paint grade finishes, exposed aggregate textures, scored grip lines for slip resistance, custom groove details, embedded nosings and blockouts for tread inserts, offering the designer more control over the product’s functionality and appearance, rather than only its utilitarian aspects.
If style is as important as utility, inquire of your supplier about the finishes and colors they provide and if coordinating or contrasting shades are available that will contribute to the overall building exterior or landscaping design.
There Are a Variety of Installation Requirements Worth Confirming
There is a difference between a flat surface to place precast stair and step units on and supporting conditions that must be provided before they are installed. Recognition of specifications requires that the supporting structural frame or foundation be checked for adherence to installation tolerances, true and level bearing surfaces and other unsatisfactory conditions which may adversely impact performance and that only then be installed.
If you’re looking for a stair dresser, inquire about their pre-installation inspection process, especially if the system will be installed on an out-of-tolerance bearing surface — otherwise, even if the system is perfectly manufactured, it could fail when it gets installed.
Identify the Following Red Flags
Here are some recurring warning signs of less successful precast stair & step suppliers. No clear distinction between stair systems and standalone steps for your particular application, vague answers to questions about concrete strength or PCI compliance, no examination process prior to installation for larger stairs, or no mention of hollow, one-piece construction for outdoor step units.
None of these in isolation should eliminate a supplier. However, two or three at a time are worth looking at again before placing an order for something that will endure the daily wear and tear for years.
The Bottom Line
The key to selecting the right precast concrete stairs or steps is to determine whether the stairs are a multi-level structure or are to be used for an entryway, and then size, reinforce and finish them appropriately for the application. If these details are correct, the product serves its intended purpose: It will safely and reliably carry foot traffic day after day without becoming the maintenance headache that no one planned for.
