Construction Design & Management Regulations 2007
Installing precast concrete floors is potentially a high risk activity which
usually involves the use of cranes and operatives working at heights.
The purpose of the following information is to highlight some of the points covered in the ‘Code of Practice for Safe Erection of
Precast Concrete Flooring and Associated Components', to assist Engineers, Designers, Contractors and CDM Co-ordinators in
meeting the requirements of the CDM Regulations. More detailed information is provided in the Code of Practice, in particular
Section 4 – Design Stage Considerations. In the text which follows the Precast Designer is not the Building Designer.
1. The Existing Environment
1.1 The sizes and weights of the components will determine the method of offloading and placing the units.
The precast units are usually delivered to site on articulated lorries; narrow roads or restricted access may necessitate
the use of rigid lorries.
1.2 Pedestrian and traffic management measures should be considered, especially if the delivery lorries are offloaded
from the public highway.
1.3 Adequate access to the work area must be provided to safely support the loads imposed by the crane’s outriggers.
Excavations, underground services, drains and basements are a hazard and strengthening may be required.
1.4 The presence of power lines, railway tracks, trees or overhead structural obstructions may hinder the operation of
cranes. On restricted sites it may be necessary for loads to be lifted over adjacent land and buildings. In these
circumstances, permission should be obtained to operate within the airspace of third parties.
2. Design and Planing
2.1 The regulations require that a designer’s competence has to be considered in the light of health and safety.
Members of the Precast Flooring Federation can demonstrate their experience and competence in the design and
manufacture of precast flooring.
2.2 To assist the Precast Designer, the following information should be provided at tender stage:
- Pre-construction information / Construction Phase Health and Safety Plan
- Design loads including finishes and imposed loads
- Drawings showing the supporting structure for the precast units and direction of span
- Phasing or sequencing of the works
- Site and services plan
2.3 Designers must take into account stability of the structure during the installation of precast units:
- The design should allow for the removal, prior to the installation of the units, of overhead obstructions such as
purlins or bracing, that are likely to foul or hinder the crane boom or suspended load.
- Precast units can be heavy. Bearings must be adequate and be robust enough to withstand normal unit fixing
operations including landing and barring.
- Lintels or steel beams must be securely fixed and have adequate safe bearing at each end to avoid overturning,
excessive deflection or collapse when the precast units are placed.
- Consideration must be given to the unequal loading of unrestrained walls, steel beams or lintels when precast units
are being placed.
- The practice of erecting precast units onto temporary bearings should be avoided wherever possible. In cases
where such measures are unavoidable the temporary structure must be designed and erected by a competent
person provided by the Contractor.
2.4 When an order is placed for the precast concrete units, the Contractor should provide the Precast Flooring
Sub-Contractor with the following information:
- Any relevant amendments to the Health and Safety Plan.
- Fully dimensioned ‘Construction Issue’ drawings, detailing the supporting structure for the floors and any other
aspects which may affect the floor design.
- Loadings, including type and location of partitions, types of finish, etc.
- Positions and sizes of all holes, notches or rebates required in the flooring.
- Provisional sequencing and programme dates.
- Where working in the vicinity of rail tracks, underground railway lines, or energy supply structures such as power
cables, all permissions that are required from owners or controllers are to be given in advance, along with any
instructions for the safe working of the Installer.
3. Construction Phase
3.1 The installation of precast concrete units should only be undertaken by specialists. Members of the Precast Flooring
Federation only employ Erectors who are trained competent and experienced in this work.
3.2 The Contractor must ensure that the Precast Flooring Federation Standard Health, Safety and Welfare Attendances
have been provided.
3.3 Installing precast floors is a high risk operation and should not be undertaken without the provision of a job specific
method statement and risk assessments which may address some or all of the following activities:
- Manual Handling
- Working at heights with risk of personnel/objects falling
- Working with cranes
- Handling or cutting concrete products, working with wet concrete or mortar
3.4 The Principal Contractor must ensure that other trades and the public are kept out of the working area covered by
cranes used for installing the precast units.
3.5 A major consideration for the Building Designer and Contractor should be the stability of the structure during the
installation of the precast concrete units:
- Sufficient time must be allowed for masonry mortar to mature enough to achieve adequate strength and stiffness.
- The designer should give consideration to the provision of adequate wall thickness, particularly where shared
bearings occur on lightweight masonry blocks.
- Consideration should be given to the proposed sequence of construction and the effects of any temporary removal
of parts of the structure to facilitate the safe installation of the precast units.
- Sufficient time must be allowed for a grouted floor to mature prior to loading out with materials, which should not exceed
the load for which the floor has been designed. Advice should be sought prior to the storage of unfixed materials on the
floors by following trades.
4. The Health and Safety File
4.1 The Precast Flooring Sub-Contractor will provide ‘as installed’ drawings at completion of the installation, showing any
changes from the original floor layout. Thereafter, the Contractor will be responsible for recording departures from
the ‘as installed’ drawings.
4.2 The flooring layout drawings will detail the loads for which the floors have been designed.
4.3 Care should be exercised to ensure that during the Construction Phase and during the life of the building, the design
loads are not exceeded and that further holes or chases are not made in the flooring without reference to the flooring
manufacturer or a competent person.
Most precast floors are constructed from prestressed units and advice on demolition should be sought from a competent
person, with access to the Health and Safety File.