INTRODUCTION

Working on roofs is acknowledged as a high risk activity because operative son roofs are exposed to the risks of falling off and falling through roofs. Where time and budget permits, equipment is available to ensure that roof workers are kept safe. ACR [CP] 005 sets out some methods by which this can be achieved. However, the ACR believes the methods set out in ACR [CP] 005 may not always be applicable or reasonably practicable for short duration work. This situation is exacerbated because there is little (if anything) in the way of guidance for workers who go on to the roof to carry out short-term work like, for example, inspecting for a leak.

This publication provides information about methods that can be used for short-term work.

SCOPE

This code of practice gives recommendations for safe systems of work for short-term work on roofs.

DEFINITIONS

For the purposes of this code of practice, the following definitions apply:

Short-term work

Work lasting for no longer than 30 minutes in any one work area.

Throwing (a line)

Action of passing a line from one side of a roof to the other.

Light work

Work that does not require any significant physical exertion.

Note: removing roof light is not light work (TBD).

GENERAL REQUIREMENTS FOR ALL SYSTEMS OF WORK

  1. The methods set out in this guidance note presume the following:

a)All operatives entrusted with using the methods are competent to the level of supervisor in accordance with ACR [CP] 006 (the Black Book);

b)All operatives entrusted with using the methods are trained and demonstrably disciplined;

c)All operatives are independently audited (unannounced) at least once a year while carrying out work using these methods.

Note: Operatives who are found to be not following the methods exactly are prevented from working using the methods set out in this guide.

  1. All work equipment used is demonstrably in good order.
  2. The roof is surveyed before work starts to ascertain whether the methods set out below are applicable. The form in appendix 1 (or similar) should be used to verify that the method chosen is applicable.

SAFE SYSTEMS OF WORK

METHOD 1: LINE OVER THE RIDGE

  1. This system of work is intended for work on duo-pitch roofs and for work where the operative:

a)requires mobility across the roof to complete the work in hand; and

b)never enters into to a fall arrest situation.

The method is also suitable for short-duration work on fragile roofs but see 9.

General requirements (all roofs)

  1. In accordance with the ACR’s advice about walking on roofs [Orange Book], whether they are fragile or non-fragile, the area of roof walked on must be restricted onlyto the area required to carry out the work.
  2. The line must not be damaged or weakened by passing over the edges (eaves and ridge) of the roof. Rope protection methods used in the rope access industry may be applicable.
  3. The method of throwing the line over the roof must not expose the operative to the risks of falling. In addition, the act of throwing the line must not endanger people not involved in the work on the roof.
  4. Before work starts, a rescue plan must be drawn up. Where this rescue plan depends on outside agencies, such outside agencies must have their role in the rescue explained to them and demonstrable proof that they understand this role.
  5. The swept area of the work to be carried out must be restricted to an area that ensures that the operative never gets closer than 2 (two) m to any unprotected edge – see Figure 1.


Note: The requirement of 9 may be ensured by tying a knot in the rope to prevent the ascender/descender device passing beyond the limits A and B.

Figure 1: Schematic of the swept area restrictions for the line over the roof method

Work on a non-fragile roof

  1. The line over the ridge method provides a safety line for the operative to anchor to while walking on a n on-fragile roof. It relies on an anchor on the opposite side of the roof to the one being worked on. The line prevents the operative from falling off the roof. The system is illustrated in Figure 2.


Figure 2: Schematic of the over the ridge method of fall protection

  1. The anchor must be able to develop 5 kN of resistance in any direction.
  2. Anchors that will generate 5 kN of resistance include:

a)0.5 m3 of water or 0.3 m3 of sand;

Note: where water or other materials that can flow from the anchor, the container should be compartmentalised to prevent a catastrophic loss of anchorage strength in the case of a puncture.

b)a 1 Te (or heavier) demonstrably immobilised motor vehicle;

Note: demonstrable immobilisation may be by, for example, the use of a wheel clamp.

c)a stake driven into the ground (not recommended for fall arrest anchors), see Figure 2 below.


Note: Advice on ground anchor verification is given in Appendix 2.

Figure 2: Illustrating the ground anchor

Work on a fragile roof

  1. On a fragile roof the anchor resistance must be increased to 15 kN.
  2. Anchors that will generate 15 kN of resistance include:

d)1.5 m3 of water or 1 m3 of sand;

Note: where water or other materials that can flow form the anchor, the container should be compartmentalised to prevent a catastrophic loss of anchorage strength in the case of a puncture.

e)a 2 Te (or heavier) demonstrably immobilised motor vehicle;

Note: demonstrable immobilisation may be by, for example, the use of a wheel clamp.

  1. On a fragile roof, this method must be used in conjunction with crawling boards to provide a designated walkway up the roof. Therefore, it is likely that this method is only applicable where the work area is restricted to a small area of the roof that can be covered by crawling boards.

METHOD 2: ROOF LADDER METHOD

  1. Roof ladders are widely available work equipment for work on roofs and are recognised by the HSE as appropriate for work on roofs. In this safe system of work, a roof ladder is used to as the anchor for the operative.
  2. This system of work is for use where mobility across the roof is not required to carry the work in hand. It is recommended only for work on roofs where the ladder can be installed while working safely. Such roofs include:

a)Duo-pitch roofs – see figure 1;

b)Mutli-pitched roofs where the valley gutter provides a safe work place.

  1. Before work starts, a rescue plan must be drawn up. Where this rescue plan depends on outside agencies, such outside agencies must have their role in the rescue explained to them and demonstrable proof that they understand this role.
  2. A line (the line) is attached to the top rung and the bottom rung of the ladder and tied off to keep it in tension. The operative installs the roof ladder in the normal way, hooking it over the ridge (HSG 33 Figure 17).
  3. The line shall be of the type used in the rope access industry.
  4. The operative shall be supplied with two lanyards; one fitted to the front of his/her harness and one to the back of his/her harness. The front fixed lanyard shall be attached to a rope access ascending/descending device.

  5. The operative shall attach the front lanyard to the line and ascend to the place of work. When at the place of work, he/she shall attach the back-fixed lanyard to the line and then release the front fixed lanyard, strictly in that order.

Figure 2: Use of a roof ladder as a work anchor

  1. On completion of the work, the process set out in 22 is reversed and the operative descends the roof.
  2. For example, when replacing a rooflight that requires two people, two ladders set up as above each side of the rooflight will be required.

METHOD 3: ROOF VALLEY WALKER

  1. Valley walkers are recognised by the HSE as appropriate work equipment for traversing fragile roofs while walking in the valley gutters.
  2. This method is recommended only for roofs where the work area is restricted to an area that is as wide as the valley walker. The valley walker is modified by attaching effective anchor points to the bottom horizontal member – see figure 4.


Figure 4(a): Schematic of anchor points on valley walkers

  1. This method is unlikely to be practical for work on:

a)fragile roofs unless there is some way of delivering crawling boards to the point of the work; and

b)roofs with a slope in excess of 10 degrees.

  1. This method is intended for multi-bay roofs where the area of roof to be worked on is between two valleys, away from the external edges of the roof. The following equipment is required:

a)A valley walker;

b)Two lanyards, one 2.0 m long;

c)An anchor line – dynamic rope.

  1. By using the roof valley walker and walking in the non-fragile gutter, walk to a position under the area to be worked on.

Non fragile roofs

  1. A person competent to do so must advise that the roof is non-fragile.
  2. Walk along the valley gutter to the point below here the short duration work is to be carried out. Place the valley walker on the roof. Make sure that the outriggers are spanning across two lines of purlins. Attach an anchor line to the designatedanchor point. The anchor line must be of sufficient length to go over the ridge of the roof in question.

  3. Attach a rope access descender/ascender device to the anchor line and walk up the roof slope to the ridge. Drop the anchor line over the ridge.The designated route up the slope shall keep the operative at least 1.5 away from any rooflight. The method is illustrated in Figure 5.

Figure 5: Schematic of method 3

  1. Carry out the work in accordance with the swept area constraints set out in Figure 3.