The Guardian Fall Team Blog

According to OSHA, a low slope roof is “a roof having a slope less than or equal to 4 in 12 (vertical to horizontal)”, and a steep roof as anything greater than 4/12. For those of you who are protractorally inclined (inclined, get it?), a low slope roof is from 0 degrees to about 18.4 degrees, and a steep roof is from 18.5 degrees on up to 45 degrees or more. Depending on which side of 4/12 your roof determines how you must address fall protection.

So What Are My Options?

On low slope roofs, as would be expected, there are a few more options available to the worker for fall protection. Or as OSHA puts it:

“…each employee engaged in roofing activities on low-slope roofs, with unprotected sides and edges 6 feet (1.8 m) or more above lower levels shall be protected from falling by guardrail systems, safety net systems, personal fall arrest systems, or a combination of the warning line system and guardrail system, warning line system and safety net system, or warning line system and personal fall arrest system, or warning line system and safety monitoring system.”

But…cross that 4/12 threshold and you are left with:

"…guardrail systems with toeboards, safety net systems, or personal fall arrest systems."

In other words, on any roof considered steep (more than 4/12) warning line systems and safety monitoring systems are no longer an available option for fall protection. Furthermore, guardrails in steep slope installations must have toeboards in order to prevent tools, other equipment, or debris from sliding down the roof and creating a potential danger to those below.

Every Picture Tells a Story

Take a look at the following graphic (OK, it’s no Picasso…wait, it could be a Picasso, sort of a cubic/geometric…oh, never mind). Notice the small green triangle on the left side of the roof, which represents OSHA’s “low slope” parameters. Above it, the red triangle represents OSHA’s “steep slope” parameters. Of course, there are roofs that go beyond 12/12 or 45 degrees, but just use your imagination for those.

Roof Slope Example

The green triangle range is where you would be able to use guardrail systems with warning lines, personal fall arrest systems, safety nets, or a safety monitoring system, and the red triangle range is where guardrails with toeboards, safety nets and personal fall arrest systems are the only compliant options available.

Warning line systems and safety monitoring systems are strictly forbidden here, so no matter how “flat” a roof over 4/12 seems – DON’T push it. The takeaway here is that a roof gains the 4/12 threshold rather quickly, and “eyeballing” a roof pitch is no substitute for determining the proper fall protection equipment.

Do The Right Thing

All this, of course, shows how important it is to have a Competent Person is on a job site. Just because a roofer may feel comfortable working on a steep slope roof without proper fall protection is no justification for doing so; neither is using a fall protection system that is incompatible with a specific installation.

Know the code, know the slope, know the Competent Person; they are there to protect you.