Great example of guarding the parapet edge when its dimensions don’t add up to the “parapet rule.” And, note the professional carpentry! This is a Taylor & Parrish job where the guardrails are always the best. (Photo: Jan Thomas)

I think all professionals have a tendency to pass-on answers based upon “rules” they have been told about but have not researched for themselves.  Such is the case with a “flat roof/parapet height rule” I was told to use back in my OSHA compliance days (hint – it’s not in the OSHA standards).

Yet, when I started consulting, I also started to check my advice to clients, being ready to pull out the necessary documents supporting my statements.  It’s so much easier to do this today with a robust internet but still some of the provenances of these “rules” are obscure.  And, not only are they hard to trace but many are not regulatory rules, only guidelines.  For example, if you have a flat roof with a parapet that is at least 30 inches tall and at least 18 inches wide, you may have sufficient protection, if you have limited exposure.  I added the part about limited exposure as I’m not truly comfortable with this “parapet rule.”

I believe this formula started as an architectural guideline.  Fall protection expert Dr. Nigel Ellis has discussed the parapet solution through all 3 editions of his Introduction to Fall Protection book (1988, 1993, 2001).  On May 2, 2003, OSHA published a proposed rule change for Subparts D and I of 29CFR1910.  At proposed Appendix A –  Fall Protection Systems,   you will find the following schematic with formula: 

I emailed Dr. Ellis recently to see if he still used this 30-inch + 18-inch rule – he calls it a flopguard.  He advocates that we all start using a 45-inch minimum high guardrail system – people around the world are getting taller!   Thanks, Dr. Ellis. It is great being able to converse with an expert.

So, to wrap up this blog, I want to say that I really do enjoy researching these fine points for our clients and I’ve got a list of them – almost all of which will make great future blog topics!  If you have an obscure “rule,” let me know and I’ll add it to the list!