Laying timber floor coverings

Timber flooring is generally supplied in two forms: solid wood planks available in various widths and types of timber, and engineered board which includes everything from a thin veneered panel available from most DIY stores, to specialised solid wood laminates. Because wood is a natural product it reacts to the surrounding atmosphere and this should be borne in mind when selecting the correct timber flooring for your home. Engineered board, made up of layers laminated together often with the wood grain running in opposite directions in each layer, is an inherently stable product. Solid timber is also suitable for use with underfloor heating, although narrower boards are recommended (no more than 150mm) as they expand and contract less with atmospheric changes.



Timber floors: Check with the flooring supplier that the material to be supplied is suitable for use with underfloor heating. Care should always be taken to make sure conditions on site are suitable for both acclimatising and laying any timber floor.



Moisture content: Moisture levels in a building prior to laying a wood floor are critical. To avoid excessive movement in the finished wood floor the tradesmen laying the floor must be satisfied that the screed, timber flooring and internal construction meet the following criteria:



• Screed: Where timber floors are to be laid over screed the moisture content of the screed should not exceed 2 – 3%, which can be checked with a moisture meter. Alternatively tape several clear polythene sheets, each 1 sq.m in area, in various places across the floor and leave for 24 hours. If there is no moisture present under them then wood flooring can be laid.



• Timber flooring: This should be kiln dried to have a moisture content of 6 – 9%. It should not be brought onto site until all excess moisture has been removed from the building as this moisture may be absorbed causing the timber to expand.



Walls and ceilings: All walls and ceilings must be dry ready for decoration. The use of dehumidification units can speed up this process.



Always leave an expansion gap around the edge of the room; typically 15mm. This will allow the floor to expand and contract with atmospheric changes and will usually be hidden by skirting.
Fixing timber and laminate floors: Use a single component trowel adhesive designed to bond timber floors to concrete screeds. This type of adhesive is suitable for use with solid or engineered strips, parquet blocks and laminate floorings.



Alternatively timber battens can be fixed across the floor prior to screeding. When the screed is fully dry the timber can be attached to the battens. Care must be taken not to damage the floor heating pipe when nailing or screwing into the battens. It is important to advise your Nu-Heat system designer if you intend to fit battens into the screed, as this will affect pipe layouts and tube quantities.