Self-build home: Prepare production information

Introduction.

In this stage, we attribute design activities to ‘designers’. These may be architects and engineers, a design and build contractor, or a kit house supplier. If a kit house supplier is only supplying the house itself, additional design consultants may be required.

Production information is '...the information prepared by designers, which is passed to a construction team to enable a project to be constructed'.

Procedure.

The designer should develop a schedule of production information, responsibilities for its preparation, a programme for its preparation and a document control system for version control.

Production information may include:

• Drawings (location drawings, component drawings and dimensioned diagrams).
  
• Specifications, calculations and design criteria. Specifications provide descriptions of the materials and workmanship required. Design criteria might include; environmental conditions, acoustic requirements, critical dimensions, accessibility requirements, loadings and so on.
  
• Bills of quantities or schedules of work. Bills of quantities are measured quantities of the work identified on the drawings and specifications that can be used to cost the works. Schedules of work are 'without quantities' instructional specifications often produced on smaller projects, or for items such as builders work or fixing schedules.

There should be a particular emphasis on equipment with long lead time times that could delay the project, such as:

• Bespoke cladding systems.
• Service diversions.
• Demolition.
• Underground drainage.
• Piling and groundworks.

Preliminary contracts might be considered for some of these works to allow them to begin early. Long-lead items such as piling rigs might also be ordered in advance of other works.

The quality of production information is extremely important. Unless it is prepared and co-ordinated properly, there will be disputes and delays on site, and costs will be incurred.

Many elements of production information will be produced by suppliers or contractors. The designer should check drawings and specifications provided by suppliers and contractors to ensure they are properly co-ordinated.

Increasingly, software is used to prepare elements of production information, such as; computer aided design (CAD) to prepare drawings, and proprietary systems for the preparation of specifications. The recent emergence of building information modelling (BIM) can allow the automatic generation of production information from a single co-ordinated model, which should result in a reduction in errors and so costs.

NB During this stage, the lead designer should also co-ordinate any outstanding information needed for remaining building regulations or other statutory approvals which must be submitted before works start on site. It is also important to ensure that any necessary party wall notices have been served.

► Next stage:

• Appoint a contractor to construct the home, or;
• Appoint a range of contractors and suppliers to construct the home, or;
• Confirm appointment of the design and build contractor to construct the home, or;
• Confirm appointment of the supplier to fabricate and install the kit house.

▲ List of all stages.