Interior walls, partitions and ceilings

1. Type of specification
Depending upon the form of contract, a decision should be made as to the type of specification required. Descriptive specifications will apply to finishes where the specialist contractor has had some design input to meet the architect's requirements. Prescriptive specifications will apply to elements where the architect has a preference for a material, product or system, and the contractor must comply with the specified materials and workmanship, such as painting or clear finishing.

2. Selection of materials and costs
The selection of materials should be made to meet the specified performance criteria. Careful consideration should be made to the client's requirements, the end use and overall budget for the fit-out elements. Early advice should be sought from the cost consultant to understand what is affordable and to avoid overspecifying.

Consider the following to determine the best choice:

Plasterboard walls/partitions, panel partitions and cubicles, rigid sheet linings (generally timber)

• Installation zone to meet performance criteria
  
• Support system (framing/battening)
  
• Durability grade to meet loading requirements
  
• Sustainability of material (in particular timber linings)
  
• Fire and moisture resistance
  
• Acoustic attenuation
  
• Air pressurisation requirements
  
• Construction and finishes tolerances
  
• Demountability (for cellularisation requirements)
  
• Finish, such as paint, fabric, glass panelling and so on.

Ceilings

• Visual appearance and flatness
  
• Acoustic attenuation
  
• Fire and moisture resistance
  
• Durability (corrosion protection)
  
• Demountability/ease of replacement
  
• Integration of services (lighting, smoke alarms, sprinklers and so on).

Painting/clear finishes

• Visual appearance and method of application
  
• Compatability of finish with substrate
  
• Durability – life expectancy to next maintenance period
  
• Corrosion protection as necessary.

3. Materials and finishes
Ensure that clauses are included in the specification with respect to all materials and finishes specified to the appropriate standards and codes of practice (British or equivalent international standards). Specified elements should include all fixings, adhesives, sealants, gaskets, metalwork and finish requirements.

4. Installation
Ensure that clauses are included in the specification with respect to workmanship and installation of the proposed systems. Specify tolerances for manufacture and installation and insist that the contractor confirms that they are achievable or propose alternative tolerances for agreement with the design team.

5. Testing
Where appropriate, specify tests that should be carried out by an independent laboratory with results fully calibrated and traceable to national standards. Alternatively, request certified and documented evidence that proves that the finishes have been tested to the appropriate standard.

6. Samples, mock-ups, prototypes
The specification should include clauses for samples to be provided with the tender and post-contract award (control samples) to enable the architect to check compliance of products as early in the procurement process as possible.

For more bespoke finishes, it is useful to specify that a mock-up of elements be provided to the architect to check for compliance with the visual design intent. Mock-ups do not necessarily need to be constructed from the final agreed products for the chosen system.

Where required, the specification should call for a prototype, or prototypes as necessary, to be constructed from materials in their final agreed form for testing as specified earlier.

7. Benchmarks
The specification should include a clause that states that the first installed and accepted section of each finish type specified be used as a benchmark for the remainder of the installation – and this shall become a reference point for the quality and standard of the works.