Guard rails, by the most recent IBC® and IRC® regulations, must be able to sustain a lateral force of 200 pounds applied 36 inches above the nose of the stringer. Neither you nor your stair railings will be safe with this. Think about the chaos if guests were on your balcony and someone fell against the railing. Suppose it was a fully grown adult. Imagine if those deck stairs were old and prone to structural damage.
An adjustable stair bracket with novel designs offers a clever answer to this problem. This rail post support system was developed to meet building code requirements for stair buildings. The basic stair bracket was modified and tested as a lateral load stair rail post support for cut stringers, angle stringers, and other uses. More than a dozen separate tests showed that every bracket could withstand 500 pounds applied 42 inches above the tread tip (an IBC requirement for non-residential applications) without giving way.
According to the National Safety Council, around 2,000 people lose their lives each year due to falls on the stairs. When a hand grip or handrail loses its stability, it drastically reduces its protection level. This is especially true of those over the age of 65. The National Safety Council reports that “falls are the leading cause of death and serious injury among people aged 65 and older.”
There are various effective methods for attaching handrails, which is essential for ensuring the safety of people using the stairs. However, this is not always the case, especially with guardrails fastened to wooden stairways. Typically, guardrails will be fastened to rail post supports, which will be fastened to a stringer. Some professionals in the construction industry are concerned that the lateral load capacity required by code is not being satisfied by the typical installation methods utilized to attach rail posts. To guarantee that all future buildings will adhere to this standard, products like the stair rail bracket reviewed in ICC-ES’s study for code officials and experts in the construction sector, ESR-2295, should be used.
How do most safety inspectors check if a stair rail is secure? It’s usually just a “tug and bump the rail” test, and if everything seems stable, it gets a pass. Staircases often include three or more cut stringers in older buildings. Stairs can either have risers and treads or just treads. The standard height for a guardrail in a home is 36 inches, and it is installed by bolting posts to the exposed stringers. The rails are often up to code, but the connection between the post and stringer is inadequate.
An IAS-accredited testing laboratory evaluated the load-bearing capacity of this time-honored method of building. Using dry #2 Douglas Fir, we cut three 2×12 stringers and two 2×6 members for each tread to build a set of stairs. Two galvanized bolts 3/8 inches diameter were used to secure three 48-inch-long poles. As is customary, the top bolt was fastened via the stringer’s triangular cutout, while the bottom bolt went through the stringer’s uncut section. As the load point, a 3/8-inch eye bolt was fastened 36 inches above the front of the tread. A dynamometer was used to apply a load to each post and measure its resistance. Each time, a load of only 20 pounds was sufficient to pull the bolt through the cut, triangular rise/tread tip of the stringer. The stringer and rail post support both failed as the weight was increased to 50 pounds, with extensive longitudinal cracks appearing throughout the length of the stringers and destroying all triangular points.
Significant structural failure occurred at modest loads throughout all three experiments, and multiple causes of this early failure were discovered. The post was a lever against the stringer, increasing the pressure on the fasteners. The top bolt was pulled through the stringer after a 20-pound pull at the guardrail level generated a 120-pound strain at the base of the post. The weight was concentrated on the bottom bolt as soon as the top bolt gave way. A last draw of 50 pounds on the guard rail resulted in a force of 1,200 pounds at the base due to the mechanical advantage afforded by the lower location of the bottom bolt. This induced a longitudinal break in the stringer due to twisting. The tests were performed on freestanding posts. Using a continuous rail can reduce the stress on the bolts at any given post by spreading the weight across multiple posts. However, the above testing accurately reflects the worst-case conditions for which the test was created. When guardrails fail, they can have devastating results.
New EZ Stairs® rail post attachment technology, as evaluated by the ICC-ES, provides a straightforward, effective, and code-compliant answer to this critical problem. Find report ICC-ESR 2295 on the ICC-ES website.
The International Builder’s Show has often named EZ Stairs, Inc’s [http://www.ez-stairs.com/] products “Hot Product of the Year.” Awards for innovation in the building and stair construction industries have been given to this stair system. It’s the only bracket system of its kind, and it may be utilized to adhere to ICC-ESR 2295 (code evaluation report) standards for interior and exterior (deck stairs, wood stairs, and concrete formwork stairs) applications. It’s cheap and straightforward to set up, which reduces setup time by 50%. To learn more, check out the interactive 3D demonstrations.
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