Working at heights in high winds

15th November 2017

We’ve gone a bit Game of Thrones with our news reports this month, starting with Dragon flames and fire on Bonfire night and we are hoping for Jon SNOW when we publish our salt/gritter loading machines later this month. As Winter is coming! We hope you find this Working at heights in high winds article of interest.

One of the frequently asked questions on the HSE website is – Is there a wind speed above which roofing work should stop?
Do not consider going on any roof in poor weather conditions such as rain, ice, frost or strong winds (particularly gusting) or if slippery conditions exist on the roof. Winds in excess of 23mph (Force 5) will affect a persons balance.

HSE Weather conditions recommendations for Working at Heights in High Winds
You should anticipate adverse weather conditions and take suitable precautions. The Work at Height Regulations 2005 specifically require that weather conditions be considered when planning any work at height. Rain, ice or snow can turn a secure footing into a skating rink. A roof should always be inspected before work starts to see if conditions have changed and to check whether it is safe to work.

A sudden gust of wind can lead to loss of balance. Roof sheets and, in some circumstances, roofing membrane should not be fixed in windy weather as people can easily be thrown off-balance while carrying a sheet up to or on the roof, particularly when handling large sheeting materials during work on industrial buildings.

It is not only in industrial roofing that care must be taken in windy conditions. A slater or tiler cannot work safely in high winds and a roll of roofing membrane can become mobile if it is caught by the wind. On flat roofs, materials such as felts are equally affected and the effect of high wind upon hot bitumen when it is being poured can be extremely dangerous.

When deciding whether to continue or suspend work, consider:
● wind speed;
● the measures that have already been taken to prevent falls from the roof; and
● the position and height of the roof and the size of the material being handled.

A competent contractor should use a hand-held anemometer to measure wind speed if large sheets are being handled.

The Beaufort scale (Table 2) gives descriptions of how trees, smoke etc will behave at certain wind speeds

Working at Heights in High Winds

Working at Heights in High Winds

Roofing work when Working at Heights in High Winds

Working at Heights in High Winds

Special consideration must be given to laying and handling sheets exceeding 20 m in length. The above maximum wind speeds may be too high, as the surface area of the sheet may make it unwieldy in lower wind speeds.

Working at Heights in High Winds

As long as this work is carried out from a safe working platform or safe scaffolding, it should be possible to provide additional protection at the work position, which should render the limitations of working in windy conditions less significant than when working directly on a roof. However, every situation should be considered individually as local conditions may increase the hazards.

Working at Heights in High Winds

Working at Heights in High Winds

Working at Heights in High Winds

The practical application of a membrane system will, however, cause work to be stopped at wind speeds lower than the 23 mph limit.

LOLER Regulations state the following with regards to Working at Heights in High Winds

Effects of high wind
Where lifting equipment and/or its load may be affected by high wind, appropriate devices should be made available and used so as to detect dangerous situations and allow measures to be taken to cease using the equipment.

Where appropriate, the maximum wind speed in which the lifting equipment can be used should be included in the instructions on use. Measures therefore should be in place to determine the wind speed and also reduce its effect.

Wind effects can be relevant both indoors and outdoors. Equipment use and selection should take account of this.

When planning the installation of lifting equipment that will remain erected in high winds, the planning process should take into account the out-of-service winds that it could be subjected to (the requirements for tower cranes are given in BS EN 14439,15 for example). The foreseeable wind speeds will depend on where the crane is to be installed. Information on historical wind speeds in different areas of the UK is available but may need to be supplemented by a local wind study, carried out by a person competent to do so, to assess the effects of the site location, terrain roughness and any tall structures in the vicinity. It may be necessary to restrict the maximum erected height or increase the size of the foundations and/or ballast.

The weather forecasting services will provide a general idea of the expected wind conditions on a day-to-day basis for a particular area. However, they cannot provide an accurate indication of the prevailing wind conditions at a particular moment in time for a particular area. Some means of providing a reliable measure of the wind speed, including gusts, may therefore be necessary.

The most common way of providing an instantaneous indication of the wind speed is to fix an anemometer to the lifting equipment. If used, it should be fixed in the most exposed position, usually on the top of the lifting equipment. Where this is not possible then other alternatives could be used, for example a hand-held anemometer or, more usually, estimates using the Beaufort Scale. However, these alternative methods may not give an accurate indication of the wind speed in the most exposed position.

The shape of the load, and the way it is lifted, could also increase the effects of the wind and consequently may affect the stability and rated capacity of the lifting equipment. The larger the surface area of the load presented to the wind then the greater the effect a gust of wind will have on the load and consequently to the strength and stability of the lifting equipment, as well as on the safety of nearby workers. This should also be taken into account when selecting lifting equipment for use. The crane manufacturer will be able to supply information on the maximum permissible in-service wind speeds and any derating for items with a large surface area.

To reduce wind effects on the lifting equipment and/or the load it may be necessary to set ‘wind action levels’, ie the wind speed(s) that require additional measures to be taken to ensure that the lifting equipment remains stable. The manufacturer will be able to provide this information.

The measures will vary depending upon the lifting equipment but could include ceasing to use it until the wind dies down, lowering the load to the ground, or dismantling the lifting equipment but ensuring it is left in a safe condition. This could apply to suspended access systems or to rope access work.

Mobile Elevated Work Platforms is included in Working at Heights in High Winds
MEWP’s can also be affected by weather conditions including strong winds and the HSE advise that high winds can tilt platforms and make them unstable. They recommend that you set a maximum safe wind speed for operation. Storms and snowfalls can also damage platforms. Inspect the platform before use after severe weather.

We hope that you have found this article on Working at Heights in High Winds of interest, as always our office staff are available for you to Contact Us and are happy to discuss any of your training queries.

Warm regards The Kentra Team

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