What is the Appropriate Height for Fall Protection Railing?

Proper Guardrail Height

There are many different types of railings on the market, not to mention the 2x4 or wire rope job-built railings you find on many construction sites. Regardless of their style or mounting method, they all must meet the same criteria. All must be capable of withstanding at least 200 lbs. of force in any direction (for General Industry) or in a downward or outward direction applied within 2” of the top edge (for Construction). In addition, all must be built to the same height in order to be compliant with OSHA regulations for employee protection.

The quick and simple answer to “What height must a railing be in order to be compliant?” would be 42”, but, as with many other things in the world of governmental compliance, there are some nuances to that answer.

The Basics

In General Industry, OSHA standards say the guardrail height railing must be 42” high. Simple!

But in the Construction Industry OSHA states the proper response is 42” plus or minus 3”. So, for all intents and purposes, your rail – in the Construction industry - is compliant if the top railing falls between 39” from the walking surface and 45” from the walking surface.

This holds true whether you are utilizing a manufactured railing or one you’ve built on your job site. When working with rigid materials, like 2x4s or metal tubing, this is pretty cut and dried, but when you’re dealing with wire rope, you need to make sure you are taking sag into account. Your wire rope – or any other flexible material – cannot deflect below 39” when the 200 lbs of force is applied to it.

So, that seems simple, right? Regardless of whether we’re discussing a rooftop guardrail system, a portable safety rail system, or a job-made railing the height of the top rail must always be 42” (plus or minus 3” in Construction).


Except for the caveats. There are always caveats.

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Guardrail Height for Elevated Workers

One such caveat specifically noted in the OSHA regulations for Construction is if workers are working on stilts. For those readers not in the construction industry, this may seem strange, but some trades such as painters, spacklers, and tapers will sometimes use stilts so they can move from one high area of the room to another without having to climb up and down a ladder or relocate their scaffold.

In the event that workers are utilizing stilts in an area protected by guardrails, the 42” requirement must be extended to match the height of the stilts. In other words, if the workers are on stilts that are 2’ (24”) high, then the top rail of your guardrail system must be at 66” (this will also affect the height of your mid-rail which is always located halfway between the walking surface and the top rail, regardless of how high the top rail is).

Measure from Working Surface

It is also important to remember that the height of 42” is measured from the walking/working surface which is not always the same as the floor or roof height.

For instance, if I’m installing rails at the edge of my roof, yet, a few inches in from the edge there is a raised portion of the roof on which the workers would be standing at any given time, then your top rails need to be 42” from that raised surface, not from the roof itself. Attaching it to the roof itself, in this example, would make the rail too low while workers were on the raised portion of your roof, putting them in danger. This would be the case for General Industry as well as Construction since maintenance workers could be working on that raised portion of the roof.

Consider the Work Being Done at the Location

Other times, the tasks we are working on inadvertently cause us to bypass the protections that have been put in place. Take a look at any multi-story construction site you pass. First, do you see rails at the perimeter of the building? If so, let’s assume the rails meet all the proper height criteria.

Everything is safe, right? But what happens when one of those construction workers needs to run some wiring, pipe, or conduit along the ceiling near the perimeter of that building? The moment they begin to climb up a ladder, they’ve bypassed their protection.

This would be the same for a maintenance worker changing light bulbs in a parking garage. In reaching those bulbs that may be located at the interior perimeter of the garage, has he or she bypassed the protection they are afforded by the walls?

It is important to know, at all times, what your fall protection is and if it is sufficient for you for every task you perform.

There Are Exceptions for General Industry Too

Finally, we can’t forget to turn to letters of interpretation to see if anything differs from the regulations as written. In this case, for General Industry, one such letter of interpretation exists.

This letter states that OSHA issued a directive that any guardrail in which the top rail is anywhere from 36” to 44” in a General Industry setting, would be nothing more than a de minimus violation, meaning no fine would be attached. In addition, proposed rule making includes permission for the continued use of existing, permanently installed rails as low as 36” because being that low does not increase the hazard to the worker and replacing them would expose workers to more danger than leaving them in place. However, this is for General Industry only.

Even if a construction worker was working in a General Industry facility with these accepted rails, they would be in violation of the construction standards. For their purposes, they would need to increase the height of the rails.

There never seems to be any one simple answer when it comes to regulatory compliance, but knowing what your starting point is makes things much easier. It’s like understanding that in general industry you need to begin looking at fall protection once your employees are exposed to a fall of more than 4’ (or 6’ in construction).

We know there are caveats to this rules, but at least the 4’ and 6’ rules give us a point from which to start. The same applies to the 42” rule with guardrails. Start there and then figure out if you need to adjust it for any of the exceptions to the rules. Rails can be a very efficient, simple solution to your fall protection issues – if done properly.

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