Best practice working on roofs

Safe access and egress

Safe access must be provided for workers carrying out work on the roof. Depending on the edge protection system being used, you should ensure that:

persons are able to access the roof through the roof edge protection without having to climb over the top rail or midrail;
access ladders are secured against movement;
where a platform is located more than 500 millimetres below the roof edge, then additional means of access to the roof is provided; and,
where an elevator, hoist or similar is used it is installed so that materials can be received at the roof level.

Assessment of the roofing material

Roofing material deteriorates with age and often does not perform as it did when it was installed. Before commencing work on an existing roof, inspect it thoroughly to determine its strength. This should, when possible, include inspection from inside the building as well as externally.

Guard railing may be used to provide effective fall protection at the perimeters of:

buildings or other structures; and,
skylights or other fragile roof materials.

Check the fixing and strength of safety mesh, paying particular attention to any signs of heavy corrosion.

If there is sarking or an underlay, this will inhibit the close inspection of the sheeting.

Excessive sagging or deflection (out of alignment) of the trusses/rafters may indicate deterioration of the structure. Strengthen any suspect areas of roof support with temporary props.

If there has been a fire, the structure must be certified as safe to work on by a structural engineer.

Skylights and penetrations left for the installation of air-conditioning can be a danger to roof workers. Fibreglass or plastic sheeting skylights should be checked and added to the interior plan of the roof so that hazard controls can be put in place to prevent the potential of a fall.

Even skylights with safety mesh can create a hazard as the worker can still break through and while not fall to the ground, could still receive cuts from jagged edges.

Brittle roofing consists of any flat, trough, or corrugated material such as asbestos cement, plastic, or glass, whether reinforced or otherwise, or any other roofing material that, due to its properties, age, or weathering, will not safely support a person at all points on its surface.

No access to brittle roofing is permitted until adequate hazard controls have been implemented. New roofing may also be composed of brittle roofing material (for example, translucent skylights). An internal inspection should be carried out by a competent person to identify the position of skylights and other areas where a worker could fall through the roof.

Where a roof has been assessed as brittle, signage should be put in place warning of the potential of falling through the roof and the requirement to use crawling boards.

Assessing the roof internally

A mobile elevating work platform from inside the building can provide a close inspection of the condition of the timber or steel structure noting any deterioration that has occurred. If the building has a ceiling, then safe access must be provided into the roof cavity.

Where it is not possible to gain access from below the roof due to the presence of existing machinery, plant or the roof structure, ceiling or bracing elements, a safe work system for working from on top of the roof should be established, and this system should be documented.

Whether the work is undertaken from above or below the roof will be determined by the hazards associated with working at height. This includes the manner in which the hazards are controlled including the risk of falling through the roof.

The preferred method of controlling height hazards while removing roofing material may be to use elevating work platforms or other temporary work platforms to gain access from below the roof.

Competencies to assess brittle roofing

It takes a high level of skill to assess the condition of a roof for stability and brittleness. Roof assessment should only be undertaken by a competent person.

A competent person should be able to:

carry out their assigned duties at the level of responsibility allocated to them;
understand any potential hazards related to the work (or equipment) under consideration;
detect any technical defects or omissions in that work (or equipment) and recognise any implications for health and safety caused by those defects or omissions; and,
specify a remedial action to mitigate those implications.

In this context, for assessing brittleness, a competent person is one who can demonstrate that they have:

thorough knowledge of roofing and of the mechanical and physical properties and behaviour of the particular roofing material and methods of installation;
extensive knowledge and experience of installing the product the roof is made of, its usage limitations, behaviour, and mode of failure in service; and,
an understanding of the effects on the product the roof is made of ‘under test’ when purlin centres are increased and decreased, and the ways the roofing material could fail when the resulting structure becomes more or less rigid.

Types of brittle roof cladding

Asbestos

The majority of brittle roofs are made from asbestos-cement which is composed of a mixture of asbestos fiber, portland cement, and water. It is made into plain sheets, corrugated sheets, tiles, and piping. Asbestos removal and disposal is subject to the Work Health and Safety Regulation 2011, Chapter 8 and the Dangerous Substances Act 2004. Asbestos sheeting should be removed intact. The breaking and cutting of asbestos sheets must be avoided as this can release asbestos fibres that are harmful hen inhaled.

The most common type of asbestos used in asbestos-cement sheeting is chrysotile (white asbestos) and the permissible concentration of respirable (that is small enough to be inhaled) asbestos fibre per ml is less than 0.01. Crocidolite (blue) and amosite (brown) asbestos can also be found in roofing material.

The removal of asbestos-cement sheeting from a roof must only be undertaken by competent persons who have the knowledge, experience, and resources necessary to allow them to work safely at height while handling this material.

The employer or principal must assess the hazards that are involved and establish a safe system of work for anyone working in the area.

Consideration must be given to the Work Health and Safety Regulation 2011 and the Dangerous Substances Act 2004, the type of equipment necessary, the training and experience of the employees involved, and the instruction and supervision required.

Employers, principals, and others involved with work involving asbestos must understand the legal requirements and necessary control measures to protect their employees and others in the vicinity against exposure to asbestos fibres.

The following specific precautions should be taken when removing asbestos-cement roof or wall cladding from buildings or other structures:

use roof ladders, crawl boards, and edge protection;
never use power tools for cutting asbestos;
asbestos-cement sheeting must never be pressure washed;
asbestos-cement sheets should be removed in one piece and lowered to the ground;
stack the roofing material on a plastic sheet in a secure area;
contain the work area to ensure there is no spread of contamination;
remove the roofing material from the site as soon as possible using covered bins or on a covered truck and dispose of material at a site approved by the appropriate disposal authority;
all asbestos-containing waste should be kept wet, wrapped in heavy duty;
polythene plastic bags, sealed, and labelled with its contents
asbestos-cement sheets must not be reused or offered for sale; and,
any asbestos-cement residues remaining in the roof space or around the removal area must be cleaned up, using a vacuum cleaner fitted with a high efficiency particulate air filter.

Glass

It was common for the saw-tooth roof to use glass as the vertical lighting panel. It is now illegal to use glass in an overhead situation unless it is safety glass.

Before working on a saw-tooth type of roof, walkways should be in place. This can consist of crawl boards, cat ladders or plywood sheets that are a minimum of 450 millimetres wide and 18-21 millimetres deep.

The recommended width of walkways is 1200 millimetres used in conjunction with individual fall arrest systems that must be fastened to the structure. Sarked roofs with timber that is in good condition may not need walkways.

Metal

Metal roofs are designed to take the weight of a worker and a bag of tools up to a capacity of 110 kilograms.

Particular attention should be paid to metal roofing material that has been subject to abnormal corrosion conditions (for example, a smelter, plating shop, fertiliser works) or in a marine environment. In these circumstances the contaminated or corroded roof area must be accessed through walkways and total restraint or fall arrest systems. Depending on the nature of the contamination or corrosion, personal protective equipment such as respiratory protection may be required.

A visual inspection is required to confirm the seriousness of any rusting. Deterioration of aluminium cladding does not show as visibly as steel and therefore flashings should be removed to ascertain the condition of aluminium cladding.

‘Walking the purlins’ is permitted on trapezoidal metal roof cladding with a flat-pan-width of 100 millimetres as this type of roof is unlikely to fail under a point load.

Fibreglass

Fibreglass, also known as glass reinforced plastic or glass fibre reinforced plastic, is a material manufactured from a combination of various elements. Primarily, it is made of a fibre-reinforced plastic resin that is intercut with fine fibres of glass for added strength and durability. As fibreglass ages it becomes brittle and is prone to breaking when walked upon.

PVC and perspex

PVC and/or perspex sheeting becomes brittle over time and loses its flexibility. Seam separation and stress or fracture cracks can appear. Some PVC used in cold climates has been known to stress-shatter leaving hundreds of little star-like fractures in each sheet. This material should never be walked on without fall prevention controls in place.

Concrete and clay tiles

When being removed, concrete and clay tiles are a significant hazard as they could fall into the building. No one should work below any area where tiles are being removed due to the risk of being hit by falling debris.

Replacing the battens on a concrete or clay tile roof can constitute a major height hazard and fall prevention measures should be used. Tile battens spaced at less than 500 millimetres apart can act as a fall prevention measure.

Composite

Composite roof and wall cladding materials made from bituminous paper and similar materials are also types of brittle roofing.

Falling materials

Isolate the area below roof work wherever there is any danger of people being struck by falling material, debris, tools, and/or material from adjacent cranes or structures.

Toe boards should be fixed to temporary edge protection as a way of containing all materials, including debris and loose tools.

Work areas must be declared a ‘No Go’ area for all persons except those directly involved in the roof work. Signage should be prominent at the entry points to the site.

The immediate working site must be isolated and no other persons must enter the area when work is being carried out above.

Electrical hazards

The position of any powerline or telephone wiring should be noted on the plans. All electrical outlets including the position of wiring to lights should be noted on the hazard management plan.

As the owner of the power lines, the network operator shall be contacted prior to work commencing to verify minimum approach distances between any part of the worker or equipment and any overhead power line.

Minimum approach distances are:

2 metres for circuit voltages 415 volts and below; and,
6 metres for circuit voltages above 415 volts.

Unless specific permission has been granted by the Network Operator the above distances shall not be reduced.

Regardless of whether permission of the Network Operator has been obtained to work closer than the above distances, there shall be a plan in place to work safely.

In all cases the plan should take the means of access, the skill level of the employees, and the nature of the work into account.

If the work could breach the Minimum Approach Distances then it must not proceed with the line live.

A safety observer should be appointed if there is the potential for the person to forget where they

are positioned relative to the live conductor.

Factors to be considered include but are not restricted to:

the nature and duration of the of task;
the need to continually relocate or change the position of the work platform;
the complexity of task (complex movement of objects, a need to adjust work position while wearing a harness or fall restraint); and,
fatigue.

Weather conditions

Check the suitability of weather conditions. Hazards resulting from adverse weather conditions should be anticipated and suitable precautions taken. Considerations relating to weather conditions include:

condition of the roof surface moisture conditions (for example, rain, ice, frost, snow);
wind speed; and,
UV radiation and sun glare.

Eliminated falls through design

Designers, manufacturers, suppliers, importers and installers of plant or structures that could be used for work must ensure, so far as is reasonably practicable, that the plant or structure is without risks to health and safety. Designers of plant or structures have an important role in eliminating or minimising the risks of falls in the design stage.

Plant requiring maintenance could be installed at lower levels of a building reducing the need to access the roof area.

Selecting the right equipment for working of roofs

Part of the hazard assessment process is selecting a control or a combination of controls to prevent falls from roofs. Outlined below are a number of options linked to the hierarchy of controls for managing hazards. Each control will have benefits and deficits depending on the nature of the work. Sometimes a number of controls will need to be used to ensure the hazards are adequately managed.

The first priority is always to eliminate the potential of a fall. Ways to do this include designing out the hazard, or working on the ground, or working from a solid construction.

Minimisation controls should only be implemented as the primary means of controlling the hazard when neither elimination controls nor isolation controls are possible.

Preventing falls from roofs

Ideally parapets over 1 metre high or temporary edge protection (or scaffold) to the perimeter of the roof should be used as these type of controls require the least use of total restraint and/or fall arrest systems.

The most desirable working area can be created when combining fully sarked roof areas with the use of safety mesh manufactured and installed to AS/NZS 4389: Safety mesh.

It should be noted that if traditional netting is used instead of safety mesh that meets AS/NZS 4389: Safety mesh, then a total restraint system or fall arrest system should be used until the roof coverings are in place.

On profiled sheeted roofs, industry standard safety nets are the preferred method of additional fall protection. In the case of insulated composite panel roofing where safety mesh may be aesthetically and/or hygienically unacceptable, the manufacturers recommend that safety nets should be provided as a collective means of fall arrest. Safety mesh should comply and be installed in line with the standard AS/NZS 4389: Safety mesh.

Total restraint should be used in preference to a fall arrest system as it prevents access to areas where a worker could fall. The rating of anchor points and the selection of equipment varies according to the type of total restraint and/or fall arrest system. W orkers using fall arrest and work positioning systems require:

training in the use of equipment and rescue techniques;
a full body harness (preferably with front attachment point for recovery/rescue and work positioning);
an appropriate length lanyard incorporating a shock or energy absorber to minimise any potential fall distances
the choice of a short lanyard (or retractable lanyard); and,
an approved rope grab and drop line.

Controls to prevent falls from a roof

Edge protection

Where there is a risk of a fall from or through the structure of a roof and there are no other means to prevent a fall, temporary edge protection and/or scaffolding should be installed.

There are a number of proprietary edge protection systems available that are suitable for a wide range of roofing situations. Edge protection should comply with AS/NZS 4994.1 and 4994.2: Temporary edge protection.

Perimeter or edge protection should be installed on all the exposed edges of a roof which include the perimeters of buildings, the perimeters of skylights or other fragile roof materials, and any openings in the floor or roof.

Roof edge protection is considered a passive fall prevention barrier, because once erected or installed, it requires no further on-going adjustment, alteration, or operation by any person to ensure the integrity of the system to perform its function. It is also a means of group control as it provides protection for anyone working on the roof.

Where guardrails are used to provide a barrier to openings in the roof, they must have a top rail, mid-rail, and a toe board, or a top rail and an infill panel that serves the function of a midrail and toe board. The top rail should be at least 900 millimetres in height above the working surface.

When there is more than one contractor on the site the principal and/or lead contractor should ensure there are adequate controls in place to prevent workers falling from or through a roof.

Working on or removing roofing material has the potential to expose workers to risks of falling from or through the roof. When replacing roof and wall cladding, temporary edge protection or scaffolding should be installed.

Where a scaffold has been provided for the construction of the walls or guttering, the roof workers may use it to complete their roof work. Scaffolding should be erected in accordance with the ,Work Health and Safety Regulation 2011 and any relevant Codes of Practice or Australian Standards.

Scaffolding and guard railing for roof edge protection

Workers should be able to gain roof access without climbing over guardrails. Access points must not undermine the integrity of the edge protection. Gates or other devices that guard openings should be self-closing and ladders should be placed as close as practicable to the entrance, and fully secured.

Guardrail systems for roofing work

Guardrail systems should include top, mid and bottom rails or toeboards. Where toeboards are used in place of bottom rails they must be able to withstand the likely impact loads.

Guardrail systems should include:

toeboards or mesh infill to prevent tools, materials or debris falling from the roof, unless a 2 metre ‘no go’ zone has been established to prevent persons entering the area below;
a clear gap between rails not exceeding 450 millimetres. The clear distance between a mid-rail and a toeboard or bottom rail should not exceed 275 millimetres;
no gap between the roof edge, including the gutter, and a guardrail located outside the roof line exceeding 100 millimetres;
a clear distance between the roof cladding and the bottom rail of not less than 150 millimetres and not greater than 275 millimetres;
an effective guardrail height above the roof surface of not less than 900 millimetres (for roofs with a pitch over 10 degrees the effective height must be measured from a point 300 millimetres inside the roof edge); and,
infill panels where the pitch of the roof exceeds 26 degrees.

Roof edge protection for gable ends

Edge protection should be provided as close as practicable to the gable ends with the scaffold no more than 300 millimetres from the structure. The mid-rail should be approximately 500 millimetres above the line of the gable (slope of the roof) and the top guardrail 900 millimetres above the line of the gable.

Total restraint, work positioning, and fall arrest systems

Using a total restraint system (fall restraint), and work positioning are recommended over the use of fall arrest systems.

The total restraint system protects a worker from approaching an unprotected edge, thereby preventing a fall from occurring.

A fall arrest system is designed to support and hold a person in the event of a fall. It is not a work positioning system as they are not designed to support a person while working.

Any static line system must be securely anchored and set up so that inertia reel lines or other types of lanyards cannot be severed on sharp edges.

Anchors should have a rated load of 15 kN for one person & 21kN for two persons. All fall restraint and fall arrest anchors should be tagged and re-certified annually to remain compliant with AS/NZS 1891.4: Industrial fall-arrest systems - Part 4: Selection, use and maintenance.

In the event of a worker falling, ensure the ‘pendulum effect’ will not cause the worker to come into contact with solid objects or the ground.

Work positioning systems

Work positioning systems enable a person to work supported in a harness under tension in a way that a fall is prevented. Generally the arrangement allows for the worker to maintain a stable position and to work hands-free while completing a task. The harness arrangement should not allow a fall of more than 600 millimetres. This is generally achieved through the use of short lanyards of 300 millimetres.

Safety mesh

Only safety mesh that has been installed in accordance with AS/NZS 4389: Safety mesh can be relied on to support the weight of a worker. Particular care is required to ensure that the mesh is securely connected to the structure and the overlap between adjacent sections of mesh is sufficient to generate the necessary strength to resist the force of a person falling onto it. Wire netting is not a barrier and is not safe to walk on.

Safety mesh should be placed over the area immediately after roof material is removed. This will enable the replacement sheets to be fixed without the necessity of using fall arrest systems. Safety mesh also minimises the time that the building below is open to the weather.

Safety nets

Safety nets are used on construction sites and similar works mainly to arrest a person’s fall, although they can also be used to catch or contain debris.

Safety nets are manufactured from synthetic materials. They are lightweight and rot- resistant, but they can be easily damaged by improper use, wear and tear, heat or flame, handling, or storage. They can also be adversely affected by weathering, UV degradation and environmental factors resulting in some strength loss. It is therefore essential that safety nets are subject to regular examinations by a competent person and are periodically tested in accordance with the manufacturer’s instructions. The manufacturer’s instructions should also be followed for installation, use and storage.

Barriers to restrict access

When barriers are used to restrict access to edges or areas where falls could occur, they should be placed at least two metres in from any unprotected edge or opening. They should be highly visible and capable of remaining in place during adverse weather conditions. The height should be between 900 millimetres and 1100 millimetres and should act as a boundary around a work area to prevent access to a height hazard such as a skylight.

Workers should not cross or work on the wrong side of a barrier to restrict access without additional protection (for example, total restraint). Barriers to restrict access should not to be used for roofs with a pitch over 10 degrees.

Roof ladders

Roof ladders may be used to provide permanent access to a work positioning system, or on pitched or brittle roofs to gain access to service plant.

Any brittle roofing should have walkways installed. These can consist of roof ladders, or plywood sheets that are a minimum of 450 millimetres wide and 17-21 millimetres thick.

The recommended width is 1200 millimetres and should be used in conjunction with individual total restraint or fall arrest systems. Ensure that permanent access complies with the Building Code.

On brittle roofs, guardrails should be permanently installed on fixed roof ladders.

A gutter may be used as a walkway provided it is 450 millimetres wide and is sarked. Therefore, synthetic membrane gutters are suitable. However, when access is possible closer than two metres from the roof edge, edge protection should be provided or a total restraint or fall arrest system used.

Temporary roof ladders should be of the same standard as for permanent installations. Roof ladders should be used on roof pitches over 26 degrees.

Walking safely on a roof

When walking on a roof, the worker should walk in the pan of the roof cladding. When this is not possible the worker’s weight should be spread evenly over two ribs, and the worker should keep as close as possible to the purlins or battens.

Metal roof cladding is tested to a static load of 1.1 kN, which equals 110 kilograms, and is meant to represent a worker carrying tools. Site supervisors should ensure workers walking on metal cladding do not exceed the recommended 110 kilograms. To ensure the roof purlins are not overstressed, two people should not stand within the same purlin spacing, or closer than 2 metres.

Never stand on translucent or clear sheeting because it is not designed to bear the weight of a worker. Cover skylights and penetrations securely or fix temporary edge protection around them.

The steepest pitch that will provide a secure footing on a textured surface roof is 35 degrees and on a smooth surface roof 26 degrees. These pitch factors only apply to clean and dry roofs. If the slope of the roof exceeds 26 degrees, a roof ladder should be used in addition to perimeter guardrails (or a fall arrest system) to reduce the likelihood of a worker slipping.

Roofing materials

At the end of the workday, or if the work is interrupted for any reason, all loose sheeting and incomplete sections must be adequately secured against possible movement by wind.

Loose packs or loose sheets that have not been securely fastened should not be walked on.

Training and supervision

Anyone working on a roof shall be given training by a competent person on how to work safely at height. Workers will require additional training for working on brittle roofing or the removal of brittle roofing and wall cladding. A competent person shall have the relevant skills, knowledge, and experience to undertake a brittle roof assessment.

Anyone using a harness system, (for example, total restraint system, work positioning system or fall arrest system) should be closely supervised by a competent person or be a competent person themselves.

A recommended means of achieving competence in using a harness system is unit CPCCCM2010B Work safely at Heights, or an equivalent or higher qualification.

At least two workers should be present when using fall arrest systems and they should be trained in the safe use of the equipment. A rescue plan should always be in place and workers trained in the rescue procedures identified in the plan.

Personal protective equipment

The use of personal protective equipment should be identified as part of the hazard assessment process. Depending on the associated hazards, some of the personal protective equipment and clothing that may be required for working on a roof could include:

non-slip footwear;
hard hat;
gloves;
eye protection;
hearing protection;
respiratory protection;
wet weather gear; and,
disposable overalls.

A surface’s ability to provide secure footing will vary depending on the type of surface cladding, environmental conditions, and the type and condition of the roofer’s footwear.

Workers on roofs should wear footwear that is in good condition, soft soled and capable of providing secure footing.

Hard hats should be worn at all times whilst working on a designated construction site.

loves should be used when handling roofing material that has sharp edges.

eye protection should be worn for any activity that could cause damage to a worker’s eyes.

Hearing protection should be worn when working in noisy areas or undertaking noisy activities. Refer to the Code of Practice for Managing Noise and Preventing Hearing Loss at Work.

Weather environment

If a safety hazard exists when roof cladding is wet due to rain or dew, or if it is very windy, the work should be postponed.

Special care should be exercised when handling long-length sheeting, particularly in wet or windy conditions as falls and slips can occur, especially if the sheeting is caught by the wind.

Where the gutters also have to be replaced, temporary provision should be made to remove rainwater from the area.

On sunny or humid days workers on roofs should keep themselves well hydrated and have access to clean drinking water. Workers should wear sunhats, keep their skin covered, and/or use sunblock to protect their skin from sunburn and potential skin melanoma from exposure to the sun.

Up-to-date weather forecasts should be factored into the hazard assessment and be taken into account prior to working at height on a roof.