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1 Compatibility

It is paramount that the flooring, adhesive and subfloor are considered as one compatible element. Advice should be sought from flooring and adhesive manufacturers on the most suitable products and installation methods. Appropriate underlay for carpet or subfloor preparation for sheet material are essential. In some cases, the finish is part of the floor substrate. For example, raised access floors used in commercial premises may have a vinyl finish bonded to the floor panels or carpet loose-fixed with studs or magnetic pads.

For easy access, the floor finish should be laid to correspond with the grid of floor panels. The substrate must be considered together with the finish for acoustic floors too, as the whole assembly works as one. This can be a problem if developers do not wish to install the finish.

2 Subfloor preparation

The subfloor finish and tolerance must be specified in accordance with BS 5325, 8203 and 8204-1, and is particularly important for resilient flooring, such as thin sheet finishes applied and usually adhered directly to the substrate. Most resilient floors require a surface regularity of at least SR2, with SR1 for thin floor coverings requiring a high surface regularity. Coverings not less than 3 mm thick are recommended in order to minimise the risk of irregularities in the substrate showing through the finish. Ensure that the base has not been chemically hardened or treated with a resinous seal if the intended finish is to be fixed with adhesives, as there may be an adverse interaction. A smooth power float finish may also affect adhesion. Advice on surface preparation should be sought from the adhesive manufacturer.

3 Concrete subfloors

On concrete and screed bases, finishes should not be laid if a base has not dried or will not protect it from water vapour or moisture from the ground. A cementitious base must be sufficiently dry to show a hygrometer reading not greater than 75% RH, as stated in BS 8203. Under good drying conditions, one day of drying per millimetre should be allowed for the first 25 mm of screed and two days per millimetre for the next 25 mm. New concrete slabs can take in excess of a year to dry. If time is not available, then a traditional damp proof membrane or other proprietary product such as an epoxy DPM may be suitable.

4 Timber subfloors

Timber bases should be clean and free of contaminants such as paint or wax, and be smooth and level, sound, rigid and dry. The moisture content of the base must be equivalent to that which will exist in service. Watch out for preservatives and flame-retardant chemicals as these can adversely affect flooring adhesives. Remedial treatments may be required.

Wood blocks may be a suitable base providing they are firmly bonded and protected against moisture. Fully adhered floor coverings may cause blocks to lift. It may be prudent to remove the blocks and prepare the subfloor as a more suitable base.

Solid timber floor boards and tongue-and-groove particleboard can be used. Floorboards should have an underlay. If used, particleboard joints should be glued with a PVA adhesive to class D1 of BS EN 204.

5 Adhesives

The correct choice of adhesive can be found in BS 5442, which tabulates flooring types and appropriate adhesives. Advice should be sought from the manufacturers, both of the floor covering and the adhesive. Health and safety should be considered when using

solvent-borne adhesives as they give off vapour that is flammable and harmful when inhaled and should only be used in well-ventilated areas, with face masks where appropriate. Refer to the Contract Flooring Association’s guide to contract flooring. Double-sided tape of the correct specification may be an alternative to liquid adhesives.

6 PVC

PVC is a popular, reasonably durable material available in semi-flexible tiles or backed-flexible sheet form with printed and embossed patterns. It should be protected against point loading of furniture and other heavy items and has varying susceptibility to cigarette burns. Coverings can have slip-resistant surfaces and anti-static properties. Joints can be welded for a neater, more hygienic finish. When backed with rubber or high-density PVC foam, resilience is improved and impact sound transmission reduced.

Cleaning with water and detergent maintains cleanliness and appearance. Historically, PVC flooring was found to shrink over time and cleaning agents were significant contributors. It is essential that cleaning and maintenance regimes are established with the manufacturers for particular applications.

7 Rubber, cork, linoleum and other finishes

Rubber flooring is available in tile and sheet form, smooth or studded, and made from natural or synthetic rubber or a blend of both. It is installed and jointed in a similar way to PVC, and has good wear and fire resistance characteristics. Properties include oil, grease and chemical resistance, resistance to cigarette burns, antistatic and colourfastness. Cork is suitable for general application and has a warm natural finish. It has good acoustic and wear characteristics, but is not good at resisting heavy industrial wear or alkaline liquids. Effective cleaning is dependent on maintaining the sealed surface finish, often with a layer of clear PVC, wax or urethane.

Linoleum is available in sheet and tile format, in plain colours or patterned effects. It is naturally non-allergenic and resistant to bacterial growth, most chemicals and cigarette burns. Glass, metal, fabrics and plastics will occasionally be considered.

Reference documents

• Contract Flooring Association Guide to contract flooring 2002
• BS EN 8203 Code of practice for resilient floor coverings
• BS EN 14085 Resilient floor coverings specification for floor panels for loose laying
• BS EN 120103 Resilient floor coverings agglomerated cork underlays
• BS 6263 Care and maintenance of floor surfaces code of practice for resilient sheet and tile flooring
• BS 5442-1: 1989 Classification of adhesives for construction: classification of adhesives for use with flooring materials
• BS EN 685: 1996 Resilient and laminate floor coverings – classification
• British Board of Agrément Board MOAT 2: 1970 Directive for the assessment of floorings