COP:site-practice; walking-roofs

12.6 Walking On Roofs 

It must not be assumed that it is safe or permissible to stand on any roof structure or roof cladding.

All roof cladding has access restrictions that are described in 3.6.2 Roof Traffic.

The manufacturer of the roof sheeting must provide technical literature stating the point load limitations of the profile. Information must indicate the positions on the sheet where persons may safely walk or stand without causing damage or alternatively indicate the necessity to provide temporary walkways.

Where free access or heavy walking traffic is expected on the roof cladding, using 0.55 mm coated steel or 0.9 mm aluminium cladding should be considered.

Roof cladding on roofs with a pitch of less than 10° is particularly susceptible to traffic damage. Low pitched roofs using 0.4 mm thickness steel or 0.7 mm aluminium are considered unsuitable for foot traffic and should be provided with walkways.

The people employed for maintenance work on air conditioning plant, chimneys, painting, or fitting television aerials often don't know where to stand and consequently cause permanent deformation that can lead to ponding and eventual failure.

When access to the roof is necessary after construction, workers must walk in the pan of trough-type profiles or within 300 mm of the purlin fastenings.

 

 

If ribs are close together so that a workman cannot place his foot in the pan, his weight must be spread evenly over at least two ribs when walking up the roof, and when walking across the roof he should step close to, but not on, the fastener.

 

 

Translucent sheeting must not be walked on unless it is designed specifically for that purpose.
Where it is necessary to use the roof as a regular access way, specifically constructed walkways must be provided. Permanent walkways must be compatible with the cladding, securely fixed to the roof structure and supported clear of the roof sheeting.
Permanent walkways must not be made from timber, produce an unwashed area beneath them or allow the buildup of debris.

If permanent walkways are not provided, cat ladders should be available for use at any time when inspection or repairs to the roof are necessary. They should be designed to be at least 375 mm wide, and the battens or steps should not project beyond the edges of the board or stringers.

It is the responsibility of the main contractor to inform the owner of any restrictions concerning roof accessibility.

 

 

 

 

12.6.1 Roof Access During Construction 

It is not safe or permitted for other trades to access the roof while the metal roof cladding is being installed. Before any person seeks or gains access to the roof, safety precautions must be taken. See 12.1 Safety
Safety information must be kept on site during construction and it is the responsibility of the main contractor to inform all trades that they must adhere to these requirements.
The main contractor must provide a prominent notice stating any limitations and the safety requirements for access. The roof must not be used as a storage area, a work platform or as support for scaffolding without total protection and planking out onto adjacent purlins.

When other building work is required to take place adjacent to, or above a roof area such as a podium roof, no work should proceed until safety and damage precautions are in place. To prevent damage occurring from above, where plastering, concreting, welding or grinding are likely, the whole area should be protected by a temporary structure or tarpaulins.

 

12.6.2 Roof Cladding Damage 

Damage occurs more easily by standing on ribs with obtuse or flatter angles.
Any permanent deformation or damage to the ribs of profiled sheeting or metal roof tiles will reduce their performance to the extent that they may leak or not meet the design load requirement. See 3.6.2 Roof Traffic.
Damaged roof or wall cladding sheets must either be repaired or replaced. To restore a damaged rib load capability to the original to comply with the NZBC, all damage must be repaired within prescribed limits.
For aesthetic reasons, any damage may be unacceptable. However, if the roof cladding is not visible, ribs can be repaired by using a saddle sealed and riveted.
 
It is technically acceptable to have two dings or creases on one sheet within one purlin spacing, providing two adjacent ribs are not damaged. Any greater level of damage requires the sheets to be replaced, and the person who causes the damage must report it and be responsible for its repair.