scaffold safety Archives | DH Glabe & Associates

Pop Quiz: 30 Questions About Scaffolding

By | Blog, OSHA Standards & Regulations, Scaffold Bracing, Scaffold Components, Scaffolding, Scaffolding Planks, Scaffolding Platforms | No Comments


It is somewhat surprising how creative workers can get when it involves scaffolding.  Just when it seems all the questions have been answered, along comes a question that raises an issue that was never addressed.  Challenge yourself to these questions and see if your answer agrees with the one given at the end of this article.

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Are You Stable?

By | Resources, Scaffolding | No Comments

Tarps and other enclosure materials, such as plastic sheeting, are typical materials used to create a desirable work atmosphere.  Many scaffolds are enclosed in screening and debris netting—I recall one resort project in Aruba where the scaffold was wrapped in a mesh to ensure, so I was told, that construction debris would not blow into the adjacent swimming pool.  In reality it was there so the guests below couldn’t see the less than productive construction workers staring at them!  And, of course, now that outdoor temperatures in North America are slowly falling, thoughts of a cozy work environment on a supported scaffold become more frequent, resulting in more scaffolds being wrapped in some type of enclosure so that work can continue.  It is interesting that wrapped scaffolding has been frequently discussed and written about and yet each year scaffolds fall over because somebody wrapped the scaffold without giving much thought to the effects that the enclosure would have on the stability of the scaffold.  Of course, one of the keys to a successfully constructed scaffold is making sure that the scaffold doesn’t fall over; this is especially important for the individuals who happen to be using the scaffold!

The concept of stability is straightforward:  The forces that want to knock the scaffold over have to be resisted.  How can this be done?  While there may be a number of methods that can be used, there are three that are most commonly used by scaffolding designers and erectors:: tying the scaffold to another strong structure that can resist the forces; guying the scaffold tower to a suitable anchor that can resist the forces, and; making the scaffold large enough so the size and weight of the scaffold are adequate to keep the scaffold from falling over.  Since the stability of asupported scaffold is desirable, standards and regulations have been written to address the issue.  The U.S. Federal Occupational Safety & Health Administration, OSHA, requires that “Supported scaffolds with a height to base width ratio of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing, or equivalent means….” [29 CFR 1926.451(c)(1)]  The standard goes on to require that when the scaffold is tied to an existing structure, it has to be tied at a frequency of no more than 30 feet horizontally and 26 feet vertically for scaffolds wider than 3 feet, and 20 feet vertically for scaffolds 3 feet and narrower.  (In California the requirements are more restrictive.)

Unfortunately, this regulation can be very misleading for the simple reason that it doesn’t address varying field conditions.  Keeping in mind that the OSHA scaffolding standards are minimum requirements and not directions or instructions, the qualified person who designs the scaffold shall determine the proper means and methods for ensuring the stability of a scaffold.  Also keep in mind that a qualified person will not guess at what is required to ensure scaffold stability.  Unfortunately, the reality is that too many scaffold erectors and users think that experience is a great method for determining what it will take to keep the scaffold from falling over.  While the OSHA mandated requirements may work for a scaffold not wrapped in plastic, the same tying requirements will be woefully inadequate for a scaffold wrapped in a tarp and subjected to a violent winter storm.  (Lucky for many wrappers, the enclosure material rips into pieces and blows off before the scaffold is yanked from its’ moorings!)  When a scaffold is wrapped in a quality enclosure, that is a netting or enclosure that is resistant to tearing, the scaffold instead will rip, bend and ultimately fail.

Interestingly, #9 wire is often used to secure a scaffold to a structure.  While this can work with an open scaffold design, it very rarely is adequate for a wrapped scaffold, even if the ties are “doubled up.”  Remember, guessing never has worked well as a substitution for a properly designed and erected scaffold.

So, what is the worker to do?  The answer is easy, logical, and in compliance with the applicable standards and good scaffolding engineering practice.  Have a Qualified Person design the scaffold.  In the case of a wrapped/enclosed scaffold, it will probably take the skills and expertise of a Qualified Professional Engineer who can design the scaffold for the anticipated forces at the specific scaffold location and for the specific time of year that the scaffold will be exposed to external forces from the wind and other environmental conditions.

If you think that you are qualified to design an enclosed scaffold answer yes or no to these statements.  (If you answer no to any of them, you are not qualified to design an enclosed scaffold):

I know where to find the information that tells me what the design wind loads are for my scaffold location;

I am familiar with the American Society of Civil Engineers (ASCE) Standard, Minimum Design Loads for Buildings and Other Structures wind loading criteria;

I know the strength of #9 wire and why it shouldn’t be used for wrapped scaffolds;

I can calculate the forces that are a result of a 100 mph breeze;

I know how to calculate overturning moments and forces due to pressures;

I know what the effects of a partially wrapped scaffold are;

I know what happens if the windows are open;

I know what effects a building corner or roof has on a wrapped scaffold;

I know my limitations.

Do You Know Suspended Scaffolds?

By | Cantilever Beam, Hoists, Scaffolding | No Comments

Are you familiar with suspended scaffolds?  Do you know the difference between a suspended scaffold and a hanging scaffold?  Well, here’s a chance to show your friends and neighbors how well you know suspended scaffolds.  Take this quiz and see if you are the best of the best.

The answers are at the bottom of the page—no cheating!

 True or False

  1. ____A suspended scaffold is the same as a hanging scaffold.
  2. ____Outrigger scaffolds are one type of suspended scaffolds.
  3. ____You don’t need to utilize personal fall protection on a Multi-point Suspended Scaffold.
  4. ____Suspended scaffold users do not need any training if they are not operating the hoists on a suspended scaffold.
  5. ____Access is not required for a suspended scaffold.
  6. ____Counterweights for a cantilever beam can be ice or Jell-O.
  7. ____The safety factor for wire suspension ropes is at least 8.
  8. ____Counterweights cannot be used to stabilize outrigger beams on Mason Multi-point suspended scaffolds.
  9. ____Guardrails are not required on two point suspended scaffolds if all the occupants are wearing personal fall arrest   equipment.
  10. ___Guardrails or equivalent are required on Boatswains’ chair scaffolds.
  11. ___Outrigger beams secured directly to the roof do not require tiebacks.
  12. ___Suspended scaffolds shall be designed by a competent person and installed under the supervision of a qualified person, competent in scaffold erection.
  13. ___Vertical pickup means a rope used to support the horizontal rope in catenary scaffolds.
  14. ___Tiebacks only need to be one half the strength of the suspension ropes since they are there for back-up, not suspension.
  15. ___Sand can be used as a counterweight provided it is in a sealed strong metal container.


Now for the tough part, fill in the blank!

  1. When wire rope clips are used on suspension scaffolds, there shall be a minimum of ________ installed per connection.
  2. A stage rated for two workers or 500 pounds can support ________workers.
  3. Ropes shall be inspected for defects by a competent person prior to each ___________.
  4. Manually operated hoists shall require a _________crank force to descend.
  5. Wire rope clips shall be installed according to the __________recommendations.
  6. A two-point suspended scaffold is supported by _________ suspension ropes.
  7. Two-point suspended scaffold platforms shall not be more than ______inches wide unless it is designed by a ________person to prevent _________conditions.
  8. Suspension scaffold means one or more platforms suspended by _____ or other _______means from an overhead structure.
  9. The toprail of a suspended scaffold guardrail system must be able to withstand a force of at least ________pounds.


True or False Answers:

  1. False.  A hanging scaffold is constructed with rigid tubes while a suspended scaffold hangs from ropes.
  2. False.  Outrigger Scaffolds are a type of supported scaffold.
  3. True.  You need to install a guardrail system.
  4. False.  All scaffold users need training.
  5. False.  Proper access is required for all scaffolds.
  6. False.  The ice may melt and you might eat the Jell-O.
  7. False.  The minimum safety factor is 6.
  8. True.  The beams must be anchored to the supporting structure.
  9. False.  A guardrail system and PFE is required.
  10. False.  How do you attach a guardrail to a chair?
  11. True.
  12. False.  Suspended scaffolds shall be designed by a qualified person and installed under the supervision of a competent person, qualified in scaffold erection.
  13. True.
  14. False.  Tiebacks must be equal in strength to the suspension rope.
  15. True.  While not recommended, as long as the sand cannot leak out, it’s okay.
Fill in the Blank Answers:
  1. 3
  2. Depends on the weight of the workers.  You can put 5 on if they only weigh 125 pounds each.  Alternatively, if Bubba weighs 400 pounds, only he can be on it.
  3. Workshift.
  4. Positive.
  5. Manufacturer’s
  6. 2
  7. 36, qualified, unstable
  8. Ropes, non-rigid
  9. 100

We Still Have Rules

By | OSHA Standards & Regulations, Resources, Safety Hazards, Scaffold Components, Scaffolding | No Comments

However, recent accidents would indicate that something isn’t quite right.  Maybe the rules aren’t being followed.  Maybe somebody doesn’t know what he/she is doing.  Maybe it’s just plain old bad luck.  I’ll agree with the first two possibilities but most certainly not the third.  Scaffold construction is not a game of chance although some might think otherwise, especially considering recent disasters.

Each time a scaffold failure occurs, there’s a strong possibility that somebody broke a rule.  But it’s not the rule or following the rule that guarantees success.  It is following the principle or action described by the rule that guarantees success.  For example, bracing is required on all scaffolds.  The bracing stabilizes the scaffold and ensures significant strength.  Removing one brace component may or may not adversely affect the scaffold.  If the construction of the scaffold is not understood, that brace may cause a disaster.  Consequently there is a rule that requires that scaffold modification be done only under the supervision of a competent person.  Could the lack of supervision been the cause of recent scaffold accidents?

Not following the rules is a result of either not understanding the rules or choosing not to follow them.  Focusing on the first possibility, not understanding the rules, might be excusable were it not for a rule established in 1970 that every employer and employee must follow the rules, in this particular case, the Occupational Health and Safety (OASHA) Standards.  You, as a user, erector, supplier, manufacturer, or designer,  must know the rules before you get on a scaffold.  No exceptions allowed.  Choosing not to follow the rules, on the other hand, appears to be a sure fire route to disaster.  But is it?  What’s more important, following the letter  of the rule, or theintent of the rule.  No doubt the intent of the rule is the better route.  Unfortunately, to make that determination, you have to understand the purpose of the rule.  To arbitrarily not follow the rule, the minimum standard if you will, makes you directly responsible for your actions.  Are you ready to accept that responsibility?

Unfortunately, many workers view the OSHA Standards as a set of instructions, which they are not; they’re minimum standards, or simply put, rules!  Many workers also think that these rules are optional.  Consequently the unlevel playing field results, the complaints about unfair competition arises, and unequal enforcement of the rules occurs.  But think about it for a minute.  What would happen if their were no rules, no minimum standards for the scaffold industry?  Would you climb a scaffold constructed under those conditions?  Would you still complain about the rules?  I think not.

As an experiment, take a look at the rules for supported scaffolds, a temporary platform supported by rigid supports such as tubes and uprights.  Pick one, any one, and think about the basis for the rule, in other words the intent of that rule.  Does it make sense?  Do you apply the intent of that rule on your scaffolds?  If not, why not?  If so, why?  As an alternative, take a look at the scaffold you are about to use, or erect.  How many rules apply to this specific scaffold?  Could you construct or use this scaffold if it were not complying with any of the rules?  Would you want to use this scaffold if it were not in compliance?  The results of such an inspection might surprise you.  Perhaps the playing field is level after all.

This article was first written and published in 1998, more than 10 years ago.  It is still applicable today, and amazingly – after 10 years – scaffold users are still not complying with the rules!

Why Is It Better?

By | Resources, Safety Hazards, Scaffolding | No Comments

It is suggested that safety in the industrial sector of the construction market is safer than the commercial sector which is safer than the residential market.  Is this true?  How can it be true?  After all, don’t the same safety standards apply to all construction?  If experience has anything to do with it, it appears that many of the safety advances that are commonplace today were born in the industrial workplace.  This is particularly true with regards to scaffolding.  If this perception is accurate, then what is it that makes the industrial sector safer than other sectors?


It is my opinion that scaffold safety involves hardware and habits.  The hardware includes the scaffold components, fall protection devices, ladders, and other products that facilitate and enhance the habits (or actions) of the employee.  The hardware cannot operate separate from the habits of the employee although the habits of the employee can function separate from the hardware.  For example, personal fall protection, such as a harness, is useless without the employee’s body wearing and using it.  On the other hand, an employee can function without the harness, however unsafe that may be.  Because of this, the employee must be encouraged to utilize the hardware so that safety is enhanced.  The industrial market, specifically refineries, chemical plants, and power plants, seized the initiative many years ago and demanded safety habits that went beyond the industry norm.  Specifically, employees using and erecting scaffolds were required to utilize personal fall protection equipment, only trained employees were allowed to erect and modify scaffolding, and a tagging system was initiated to provide some indication of the status of scaffolds.


It can be argued that the controls seen at the typical industrial site are easy to institute compared to a commercial site.  Oftentimes the industrial site owner is directly involved in the safety process and is willing to compensate the employer for enhanced safety procedures.  Frequently the scaffold erector has been to the site before, and in some cases never leaves the site.  Familiarity with the surroundings and knowledge of the specific jobsite requirements, learned over a considerable time frame, are certainly valid arguments for increased safety compared to the newness of a new high rise building that changes shape and size every day.  But just a minute; ask anybody on an industrial site about the potential for serious injury or death and they’ll tell you in no uncertain terms that the exposure is just as high as a commercial site.  So is there a difference?


Yes and no.  The opportunity for an employee to get maimed or killed exists no matter what the construction site is.  As far as I’m concerned, it’s the approach to safety that makes the difference.  Oil companies have very specific rules and procedures to minimize the injury risk.  These procedures have developed over time and are continually modified and improved as more data and experience are developed.  Commercial contractors and owners can learn much from this work.  No doubt there are many general contractors who have developed effective safety programs.  Unfortunately the effectiveness of the program drops dramatically as the procedures are applied to subcontractors and sub-subcontractors.  Herein lies the problem.  Certain commercial employers choose not to grasp the significance or magnitude of the safety issues.  They need to take a cue from the industrial market.  It seems the residential market is at the bottom of the scale.  And this shouldn’t be a surprise.  The employees receive less training, have less experience, and maintain poorer habits.  We have a tendency to throw hardware at the problem and find that the result is still the same; the employee still gets hurt.  What’s the secret?  Look at the industrial segment.  Training, experience, habitual and incessant focus on safety, and a substantial enforcement incentive produce much better results while applying the same safety standards.


This is not to say that the industrial sector cannot be improved.  The Scaffold Industry Association Training Program (SIATP) has developed a customized Industrial Training Program that specifically applies to employees involved with scaffolding in that market.  If you’re in that market, avail yourself to that training; who knows, your habits may need adjustment.  If you are in other markets, the SIATP has programs that will help you and your habits.


Remember, the rules are the same and they should be applied the same.  Safety on industrial, commercial, and residential jobsites is the same.  It’s the habits that make the difference.  It is your habits that make the difference.

How are we Doing?

By | Fall Protection, Guardrail, OSHA Standards & Regulations, Resources | No Comments

In January of this year I wrote an article titled “A Better New Year?” The article described fatality statistics in the construction industry. If you will recall, in 1997 there were almost 700 fall related deaths which means that, on average, there were at least two deaths per workday attributed to falls! OSHA statistics indicate that typically 19 per cent of these fall fatalities were from scaffolds; in other words, approximately every two workdays a worker dies due to a fall from a scaffold.


Needless to say, there’s room for improvement. The Federal Occupational Safety & Health Administration, (OSHA), has addressed this concern in both Subpart M, Fall Protection, and Subpart L, Scaffolds, by issuing standards that set the minimum requirements for fall protection for exposed workers. While there are a number of methods for minimizing fall hazards, Personal Fall Protection Systems and Guardrail Systems are two of the most common methods that are used. Interacting with these two methods is another aspect of fall protection that is equally important as the hardware, and that is training.


Remembering that fall protection has been required for users of scaffolds since at least 1971, (and certainly before that if you choose to comply with the American National Standards Institute (ANSI) standards), it should be amazing that any scaffold users fall from scaffolds. And yet, we haven’t figured it out yet. Users are still falling in spite of all the requirements. Erectors are falling too. Again, using the OSHA statistics, 11 per cent of scaffold fall fatalities are erectors. That works out to about one erector every three weeks who dies falling off a scaffold. Seems to me that this fact would be good justification for addressing fall protection for erectors.


Safety on the jobsite is based on a number of assumptions. The first assumption is that the standards, regulations, guidelines, and practices are correct and accurate. The second assumption is that the regulations are enforced equally, accurately, and correctly. The third assumption is that those responsible for enforcement are knowledgeable and properly trained. The fourth assumption is that workers are properly trained, knowledgeable, and conscientious. The fifth assumption is that the equipment is designed, manufactured, installed, and used correctly. The sixth assumption is that the first five assumptions aren’t necessary for jobsite safety. Therein lies the problem. If any of the first five assumptions is considered invalid, and consequently not met, safety is compromised and fatalities occur.


Are we assuming too much? Is it possible that the standards are inadequate and that these standards somehow cause fatalities instead of preventing fatalities? As far as I know, there is no evidence of inadequacies in the standards; therefore we are not assuming too much in expecting the standards to be minimum expectations for behavior.


It may be too much to expect equal enforcement of the standards but that has more to do with how often we choose not to meet the standards. In the case of fall protection, we may choose not to employ fall protection measures for a variety of reasons, some valid, some not. Obviously, to say fall protection for erectors cannot be done is the easy answer to a complex question. On the other hand, requiring workers to tie off without a thorough analysis of the situation is equally as hazardous. Consequently, proper evaluation and accurate enforcement of the fall protection standards requires trained personnel, which leads to the third assumption.


How can we expect proper enforcement if we don’t give the enforcers proper training and tools. Is it reasonable to expect anyone to have a thorough knowledge of all the standards, especially when we (that’s all of us) don’t provide funding for the training? How well do you know the standards? Do you know how many there are? I believe that the individual charged with the implementation of compliance with the standards and regulations has a formidable job! In fact, to assume that any individual can master all the standards is unrealistic.


Assuming that the workers are properly trained is a huge assumption that is rarely fulfilled. The evidence shows that we have a long way to go in getting the worker to use proper fall protection, in getting the scaffold erectors to understand proper fall protection techniques, and getting owners to cooperate in providing the hardware so that fall protection can be provided. What’s the evidence? A death every two workdays.


The fifth assumption, that the equipment is designed, manufactured, installed and used correctly assumes many things. While fall protection equipment typically is designed and manufactured to a high degree of sophistication and reliability, improper installation and use can, and does, negate those qualities. Since the user may be untrained, the installation, and therefore the use, of the equipment may be wrong. If all that is wrong, then the potential for death greatly increases, proving that the best efforts by some can easily be negated by the incompetence of others.


Finally, assuming that proper standards, proper enforcement, proper training, and proper equipment are not necessary, is the biggest mistake. We are all in this together, whether we like it or not. What have you done this year to ensure that the standards are accurate, the implementation of those standards is accurate, that those charged with the implementation have the training and tools to do so, that the workers are properly trained, (as required by the standards,) and the equipment is used properly? Good fall protection equipment is useless in the hands of untrained users; good fall protection standards are useless in the hands of untrained users. So, how are we doing?


By | OSHA Standards & Regulations, Resources, Safety Hazards, Scaffolding, Scaffolding Planks | No Comments

A friend with the Occupational Safety and Health Administration (OSHA) sent this sketch to me. He asked for my opinion concerning the safety of the installation and whether this scaffold complied with the OSHA Standards. What would you answer?


We can analyze this scaffold two ways:


1. Is this scaffold safe?

2. Is this scaffold in compliance with applicable standards?


Let’s look at the safety issue first. The platform is at two levels. Assuming that the frame is 5 feet tall and 5 feet wide, both platforms are less than five feet above the level below. Is this safe? If the platform is cantilevered over a boiling vat of sulfuric acid, you may want to consider fall protection. On the other hand, if the scaffold is in the local pillow factory, there probably isn’t any problem. What about the width of the platform? What about the relative relationship between the two platforms? What about having the lower platform supported by an intermediate horizontal support, typically a member that is about 1 inch in diameter? Is there safe access? What work activity is this scaffold supporting? These are questions that the competent person should ask when evaluating this scaffold.


Typically the scaffold industry accepts the fact that a work platform should be at least 18 inches wide, meaning that two 2×10 planks is the minimum platform width. (This fact is confirmed by OSHA, ANSI, and Cal/Osha.) It would appear that this scaffold meets those criteria. However, it seems that a hazard could exist due to the gap between the platforms, especially since these platforms are at approximately the same elevation. A worker, concentrating on his/her work, may quickly look over, see a platform, and think it is continuous; stepping backward would be disastrous!


An intermediate ledger supports the lower platform. Is this permissible? Sure it is, limited only by the strength of the supporting member. Under normal circumstances, this smaller diameter ledger will still be stronger than the typical platform. In fact, the beauty of these frames is that they can support platforms at different elevations, and they can support the side brackets at various elevations too.


Access via the frame is probably not possible due to the overhang of the plank. A clamp-on ladder or other safe means of access would be required. Finally, there is a danger of the scaffold over-turning due to an excessive load on the side bracket platform. The scaffold would require counterweights or a tie to another substantial structure to be sure that the scaffold would remain stable.


Analyzing the scaffold based on the applicable Federal OSHA Standards will produce similar results as the first analysis. This shouldn’t be surprising since the standards have been established to address hazards such as the ones already described. The most common question that is asked regarding a scaffold such as this one concerns the width of the platform. Regulation 29CFR 1926.451(b)(1) frankly states that “each platform on all working levels of scaffolds shall be fully planked or decked between the front uprights and the guardrail supports as follows…” If you think that this means that the platform should be across the full width of the frame, take another look at the side bracket platform. Where is the upright? Where is the guardrail support? The upright is behind the platform, and there is no guardrail support! What’s a worker to do? For that matter, what’s a compliance officer to do? Ask the questions: What is the intent of this regulation? What hazard does this regulation address? It’s simple, the regulation addresses fall protection. Since this platform is only 5 feet above the level below, there is no hazard, based on the OSHA fall protection standards. The standard, in particular 29CFR 1926.451(b)(2), requires that all frame scaffold platforms shall be a minimum 18 inches wide except in certain specific circumstances. The platforms on this scaffold comply with this regulation.


Do any standards address the intermediate ledger that supports the lower platform? The answer is found in 29CFR1926.451(a)(1) which specifies that “each scaffold and scaffold component must be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load applied or transmitted to it.” As long as the live load applied to the ledger is no more than 25 per cent of the maximum load it can support, we are in compliance with the regulations.


As described earlier, access via the frame rungs/ledgers, is not permitted due to the assumed overhang of the plank. (If there is no overhang, and if the rungs/ledgers are spaced properly, the frame could be used as access.) As described in the standards, safe access includes stairs, clamp-on ladders, portable ladders, and direct access. Access between platforms would not be necessary if the horizontal distance between the platforms is less than 14 inches, and the vertical distance between platforms is no more than 24 inches. (See 29CFR1926.451(e)(8))


Finally, stability for this scaffold is addressed in the supported scaffold criteria sub-paragraph. Several regulations require that supported scaffolds, including frame scaffolds, shall always remain plumb and level.


In summary, this analysis shows that good construction practice can, in many instances, exceed the standards. This isn’t surprising since the standards are minimum requirements for the construction and use of scaffolds. The analysis also shows that:


1. The minimum width of a typical frame scaffold platform is 18 inches.

2. Workers on platforms more than 10 feet above the level below must have fall protection.

3. Platform fall protection may be required at lower heights, depending on exposure to hazards.

4. The platform does NOT have to extend all the way across the full width of the frame although this may be the easiest way to provide fall protection.

5. Access shall be provided for all platforms more than 24 inches above the level below.

6. Supported scaffolds must remain stable and plumb at all times.