A decision should be made as to whether a descriptive or prescriptive specification is required. Descriptive specifications apply to finishes or elements that require a specialist contractor to meet the architect's visual intent and structural performance criteria; prescriptive specifications apply to elements where the architect has a preference for a particular material, product or system with which the contractor must comply.
Careful consideration should be made to client/employer requirements for the building, its end use and overall budget for the fit-out. Early advice should be sought from a cost consultant to understand what is affordable and to avoid overspecifying.
3. Selection of materials
There are many types of interior floor finishes classified under the Common Arrangement of Work Sections for Building Works:
- K21 – timber strip/board fine flooring/linings
- K41 – raised access floors
- M10 – screeds
- M12 – trowelled bitumen/resin/rubber-latex flooring
- M40 – stone/concrete/quarry/ceramic tiling/mosaic
- M41 – terrazzo tiling/insitu terrazzo
- M50 – rubber/plastics/cork/lino/carpet tiling/sheeting
- M60 – painting/clear finishing.
The selection of materials should meet the specified performance criteria. Consider the following to determine the possible choice of materials to satisfy the design:
Hard floor finishes<
- Sustainability of materials
- Quality of stone to ensure freedom from vents, fissures, cracks, discolouration or other defects
- Dimensional composition of flooring finishes, particularly thickness to accommodate dead and live loads
- Floor services, including floor boxes
- Reinforcement requirements
- Construction tolerances
- Type of joints, such as bay and relief joints
- Structural slab finish
- Full adhesion
- Absence of cracking to grouted joints
- Grade of material to accommodate floor loading
- Slip resistance
Soft floor finishes
- Wear resistance and durability
- Fire resistance
- Dead and live loads
- Dimensional stability
- Light, wetness, shampoo and rubbing fastness
- Static properties and slip resistance
- Compatibility with substrate materials.
4. Meeting the standards
Ensure that clauses are included in the specification to ensure all materials and finishes specified meet British or international standards and codes of practice. Specified elements should include all fixings, bedding, adhesives, sealants, gaskets, metalwork and finishes.
5. Installation requirements
Ensure the specification includes clauses on workmanship and installation of the proposed floor finishes. Specify tolerances for manufacture and installation and insist the contractor confirms they are achievable or proposes alternative tolerances.
6. Testing requirements
Where appropriate, specify tests. These should be carried out by an independent testing lab and the results should be fully calibrated and traceable to national standards. Alternatively, request documentary evidence that floor finishes have been tested.
7. Samples, mock-ups, prototypes and benchmarks
The specification should include clauses for samples to be provided at the tender stage and after the contract has been awarded to enable the architect to check compliance of the products. Samples should be provided early in the procurement process and agreed as a contractual matter for the completed installation.