Bowens - The Builders Choice

A Guide to Achieving a Successful Timber Floor

Building Advice
Jeff Harvey

Prevention is better than cure

Historically, flooring is the product that causes the most post installation problems. So, continuing the theme of prevention is better than cure, I write with some experience of many of the issues I have come across. 

Many a sale has been made from a flawless sample or glossy print showing no gaps or other features that can appear when the flooring is supplied or in the case of gaps, appearing after installation. Flooring samples, displays or images can only ever be indicative of the finished floor. Flooring is available in many varying grades and being an organic product will inherit characteristic variations that are considered normal. 

Pre-supply comments

Our customers and more importantly the homeowner need to understand the basic material that makes the flooring product is wood and wood is hygroscopic. My dictionary defines hygroscopic; “absorbing or attracting moisture from the air”. Accordingly, this means there may be some minimal post installation movement in the flooring, shrinkage in summer months or expansion in the winter. 

Installation aims 

  • The dwelling/extension must be at lockup stage and have all external doors and windows installed. 
  • Do not lay the flooring before the plaster is installed. This is a wet trade and will affect the humidity in the home. 
  • The sub-floor space for a timber cavity must be dry. All storm water points must be connected to external drainage. 
  • Sub-floor vents must have drawing capacity to regulations. 
  • The vents should be positioned below the level of the bearers, free from obstruction. The regulations mandate vents should be positioned for every lineal meter of the external walls. Opposite positioning of the vents will help achieve crossflow ventilation. 
  • Any sub-floor air/heating ducts must be tied to the bearers and off the ground. 
  • All sub-floor structural members should be dry/stable. 
  • Today, most floors have a Particleboard substrate, it should be rough sanded and level to industry standards. 
  • If the flooring is to be laid over a concrete substrate, a moisture barrier/seal is required. 200um black plastic is an economical barrier you can use under a plywood substrate. 
  • For solid flooring, a minimum 12mm plywood substrate must be fixed to the slab. 15mm thick plywood is preferrable. 
  • If Engineered flooring is going to be directly glued to concrete, then an appropriate adhesive with a moisture control layer must be used. Do not directly stick solid timber flooring to concrete. 
  • Use an appropriate adhesive that is ‘full troweled’ over the entire substrate using the recommended trowel. 
  • Understand the requirement for acclimatization of flooring is relevant to the environment the flooring will experience when lived in. 

Post installation care

  • Avoid building garden beds against the home that are higher than the concrete slab. In conventional sub-floors avoid storing any material that can restrict air flow to vents. 
  • North/West facing windows should have curtains/drapes to avoid excessive exposure and subsequent gapping from the sun.
  • Do not seal the house over extended periods of time, particularly in the summer, the house can become a hot box causing excessive shrinkage. 
  • To protect the floor, finish pads should be fixed to chair and table legs. 
  • Move matts and rugs regularly to avoid colour changes compared to boards always exposed to light. 
  • Clean up any liquid spillages quickly, repair any leakages from a dish washer or washing machine. 
  • Never use a dripping wet mop to clean the floor, it should be well wrung of water. 
  • Never leave air conditioners for long periods of time, the flooring may adjust to that micro-climate causing unwanted timber movement. 

If you have any questions regarding flooring installation, please don’t hesitate to contact me at [email protected] 

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