The Dangers of Various Roof Slopes
Derek Tokarz • Certified in Safety Management Group's Training in Fall Protection
Keeping your crews safe and protected as they work on rooftops is vital to the success of your operation. Work crews need to understand the different hazards and dangers that each type of roof slope poses. If you’re regularly working on roofs, then you’ll certainly want to understand the dangers of various roof slopes, safety precautions to take and the safety equipment that works best for each.
How OSHA Defines Roof Slopes
The Occupational Safety and Health Administration (OSHA) sets the standards for different types of roof slopes. OSHA separates roof slopes into two categories — low slope and high slope roofs. From there, OSHA sets the safety standards and makes recommendations for working on each type of roof slope. You’ll need to fully understand the type of roof slope you’re working on before organizing your safety equipment, configuring your personal protective equipment (PPE) and beginning your roof construction project.
Roof slopes are determined by measuring vertical rise over horizontal run and this number is expressed as a ratio. Below, we break down the ways OSHA defines both types of roof slopes and the risk areas to identify on each type of roof as a way to keep you and your crews safe and protected.
Low Slope Roofs
OSHA defines low slope roofs as those having a vertical rise to horizontal run ratio of 4:12 or less. The standard here is the horizontal run of 12 inches. According to OSHA, for every 12 inches of horizontal run, the rise must be 4 inches or less for that roof to be classified as a low slope roof. When OSHA is defining and categorizing roof slopes, the constant number used is 12 inches of horizontal run. Using this standard, OSHA can further classify roof slopes.
High Slope Roofs
High slope and low slope roofs are the only two types of roof slopes that OSHA categorizes. Since we already know that a roof with a vertical rise of 4 inches for every 12 inches of horizontal run is considered a low slope, then we can begin to classify and define high slope roof types. If a roof’s slope is greater than 4:12 — that is, the vertical rise is higher than 4 inches for every 12 inches of horizontal run —then that roof is classified as a high slope roof. Obviously, high slope roofs pose more risk to roofing and construction crews.
An Overview of the Risk Areas of Different Slopes
When you’re working on a roof, there are different risk areas that you can identify. OSHA determines the different risk areas that need to be marked and identified on any roofing project. Whether you’re repairing, servicing or building a roof, you’ll want to clearly identify three risk areas. The red zone, orange zone and green zone are designated by their proximity to the leading edge of a roof, and there are different hazards and safety requirements associated with each zone. These zones become more important to identify as the slope of the roof you’re working on becomes greater, and you’ll need to consider different safety measures for each zone.
Below, we break down the three different zones associated with working on a rooftop, regardless of slope.
The red zone is the area that accounts for the first six feet closest to the leading edge of a roof. This zone poses the greatest risk for falls and other accidents. Tools used in this zone, and all zones for that matter, need to be secured and protected to ensure the safety of those on the ground below a roof. The red zone poses the most risk to worker safety as slips, trips or falls in this zone can lead to serious injury or even death. In the red zone, a worker’s proximity to the leading edge makes hazards much more dangerous to worker safety. OSHA requires fall protection, guardrails and other lifeline systems such as anchors in the red zone. Regardless of roof slope, you’ll need to take safety precautions in the red zone.
The orange zone is the area that covers 6 to 15 feet from the leading edge of a roof. The orange zone still poses risks such as falling and tools dropping from the roof onto those standing on the ground below. The orange zone is where the OSHA regulations start to become less clear as there are options to create a designated area for performing “infrequent and temporary” work. If an employer designates an area in the orange zone, then this is typically done by utilizing a warning line system. OSHA does not specify which types of tasks can be designated as “infrequent and temporary” so logical safety measures will need to be implemented in the orange zone. You’ll still need to take measures to ensure worker safety such as fall protection, guardrails and anchors.
The green zone is the area 15 feet from the leading edge and in. This is essentially the middle of the roof where risks are at their lowest, but safety measures and worker protections are still required. In the green zone, fall protection or a designated area are still required by OSHA regulations. Like the orange zone, work performed here can have “infrequent and temporary” designations where fall protection is not required. It is important to consider fall protection regardless of the designated area as there are many types of hazards that pose threats to worker safety in the green zone. Skylights, random elevation changes and trip hazards all pose a potential risk to worker safety and well-being.
Best Types of Safety Equipment for Different Roof Slopes
Understanding the types of safety equipment you need for working on various roof slopes is vital to ensuring worker safety and reducing job site hazards and accidents. Safety equipment is necessary for any type of job site, but when workers are performing construction or maintenance on elevated, sloped surfaces such as a roof, safety equipment becomes vital to getting the job done properly. Federal regulations require some form of fall protection safety equipment or systems to be in place and made available for workers performing tasks at an elevation higher than six feet.
Fall protection equipment and systems can be classified into different categories such as:
Personal fall arrest system (PFA)
Warning line systems
Fall monitoring or safety monitoring systems
Whether you’re working on low slope or high slope roofs, you’ll need to supply a combination of the different types of safety equipment listed above. Let’s break down each type of fall protection by describing what they consist of and how they work to keep your crews safe on the job site.
Personal Fall Arrest System
A personal fall arrest (PFA) system is used by most roofing professionals and is a preferred piece of safety equipment for job sites that expose workers to dangerous heights. A PFA typically consists of some sort of harness and suspension system designed to catch a worker who falls from a roof or other elevated platform. PFAs are harnesses attached to the roof using an anchor and a lanyard to suspend a fallen worker and protect them from dangerous accidents. PFAs are excellent for protecting workers from a trip and fall accident where they lose their footing and can potentially fall off a roof.
Safety nets aren’t just for circus performers and fire department rescues. Safety nets are webbed or mesh netting systems generally made of synthetic or natural fibers. OSHA regulates the types of nets that you can use on a job site as a form of fall protection. There are federal regulations surrounding the size of the holes in the mesh or webbing, the amount of weight it can withstand and how often it should be tested.
Guardrails are one of the oldest types of fall protection and are typically located around the perimeter of a job site. Guardrails can be installed as temporary or permanent fall prevention solutions around rooftop work areas. OSHA details regulations for using guardrails including their height, location and material composition to ensure proper safety measures are being met. When guardrails are used on a high slope roof job site, they must include toeboards for added protection.
Warning Line Systems
Warning line systems are comprised of a rope, chain or wire barrier designed to alert workers of an unprotected area of the job site. Warning line systems offer fall protection as they should be able to withstand 500 pounds or more of weight. Warning line systems are used in combination with another fall protection system such as guardrails, nets or PFAs on both high slope and low slope roofs.
Fall or Safety Monitoring Systems
Fall monitoring systems are not pieces of safety equipment or a high-tech fall prevention solution. Monitoring systems are techniques used to alert workers when they are approaching a dangerous area of the job site where one person carefully monitors the actions and movements of a single worker on the job site. Fall monitoring systems require diligently watching workers on rooftop job sites by a trained and credited monitor. These monitors are used in combination with other fall prevention systems such as nets, guardrails or PFAs across both low roof slope and high slope job sites.
Safety Tips for Working on Low Slope Roofs
When working on low slope roofs, it’s normal to take your safety and fall prevention measures less seriously than you would on a high slope roof job site. This is when accidents are more likely to occur, so you’ll want to approach a low slope roof with the same level of diligence as you would a high slope roof. Here are a few safety tips for working on low slope roofs:
Always inspect your safety equipment such as hard hats, PFAs, safety nets and guardrails prior to beginning work
Identify any potential rooftop hazards such as skylights or holes and cover them or cordon them off so they are clearly marked
Secure all tools and job site equipment to ensure they are not at risk of falling and injuring ground crews
Utilize one or more fall prevention tactics such as guardrails, PFAs and safety nets
Use warning lines combined with guardrails or PFAs
Again, approach a low slope roof with the same level or respect and caution as you would a high slope roof. Following simple safety precautions can prevent falls, injuries and even death.
Safety Tips for Working on High Slope Roofs
Working on high slope roofs clearly poses risks and safety hazards that low slope roofs do not. OSHA sets a higher standard and requires you take additional safety measures on high slope rooftops and job sites. As we discussed earlier, high slope roofs are classified as those with a vertical rise of 4 or more inches for every 12 inches of horizontal run. High slope roofs are often referred to as steep slope roofs, so these terms tend to be interchangeable within the roofing industry. Here are some safety tips for working on high slope roofs:
Employ a combination of two or more fall prevention tactics or equipment such as guardrails with PFAs and safety nets.
Utilize toeboards in combination with guardrails to ensure OSHA compliance
Double-check PFAs to ensure they fit properly and are capable of suspending a worker in the event of a fall situation
Inspect all safety equipment such as nets, guardrails, hard hats and PFAs before you being work
Train and educate your workers on the hazards of high slope job sites and ways to prevent accidents and falls
Secure all tools and equipment to prevent them from sliding off a roof and injuring ground crews
Always use ladders that extend at least three feet beyond eaves to ensure workers can safely access a high slope roof
These are just a few safety tips for working on high slope roofs. Be sure to consult OSHA regulations and documentation to ensure you’re following all safety regulations for conducting roof work.
Kattsafe Has a Wide Variety of Safety Solutions for Every Roof Slope Type
Since 1975, Kattsafe has been providing safety solutions designed to protect your crews and return your workers home safely to their loved ones. We believe that fall prevention is about more than safety, it’s about family! Our line of fall prevention and safety products includes:
At Kattsafe, our products are OSHA compliant so you don’t have to worry about following regulations. We take the guess work out of providing fall prevention and other safety solutions for your work crews. Whether you occasionally perform roof work or specialize in roof work, you can trust your crews are safe with our wide range of products.