Preventing floor collapse

Background

Incidents involving the collapse of existing or partially built floors during construction, refurbishment or demolition works can result in death or serious injury.

Floor collapse is often due to one or more of the following:

• overloading with construction materials, plant, demolition material and rubble
• the new floor is not structurally adequate or complete
• the floor is not built to design requirements, or
• structural support elements are inadequate or have been altered or removed.

The load bearing capacity (LBC) of the floor is normally designed for the intended end use of the building, not for construction live loads (ie the weight of persons,
plant and materials involved in the construction work).

Note: a floor’s LBC has two load ratings that have to be considered, the uniformly distributed load, and point load (concentrated load).

Control measures

Existing floors

Builders and demolition contractors should:

• know the floor’s LBC
• monitor the work as necessary to ensure the floor is not being overloaded, and
• inform workers and contractors (including delivery drivers) who will load the materials, plant etc, of the LBC limitations (eg site induction, prominent signage).

Where the floor’s LBC is unknown or the floor or its support structure is damaged, a competent person (eg structural engineer) should be consulted to determine its LBC.

Floors under construction

Before loading a new or incomplete floor with floor sheets, packs of timber, beams etc, builders and demolition contractors should ensure:

• floor support members are installed and fixed as per the floor design
• a competent person has determined the LBC of the floor or support members
• the weight of materials to be loaded is known, and
• persons who are loading materials are aware of the floor’s LBC limitations, including loading sequence or positioning requirements.

This is particularly important when builders or contractors use available load shifting equipment (eg cranes, telehandlers) to place bulk materials onto the floor or its support members.

Safe work method statement (SWMS)

A safe work method statement (SWMS) must be developed and followed if the loading work:

• is part of demolition
• has a risk of a person falling 2m or more, or
• is on a floor with temporary supports to prevent collapse (eg builder’s props).