Floor Facts

Expansion gaps in floors all floors, are only in place to protect the floors for normal internal seasonal changers.

If expansion gaps in the floor close up and the floor continues to grow with visible sings of cupping, buckled or wrapped, then there is a definite problem with the  moisture level of the environment where it has been installed.

As water moves to the lowest point, the floor is usually the first indicator of the larger problems to come. In reality the product & installation account for less than 5% for all flooring issues, but are blamed incorrectly 95% of the time.

New South Wales

Generally, variations in the surface colour, texture and finish of walls, ceilings, floors and roofs, and variations in glass and similar transparent materials are to be viewed where possible from a normal viewing position. A normal viewing position is looking at a distance of 1.5 m or greater (600 mm for appliances and fixtures) with the surface or material being illuminated by ‘non-critical light’. Non-critical light means the light that strikes the surface is diffused and is not glancing or parallel to that surface.



Flooring section from the NSW fair trading Guide to standards & tolerances

Please note that only structural timber flooring is referred to in this guide.

15.1 Timber flooring – shrinkage and swelling

Timber flooring will shrink or swell according to its internal moisture content, timber species used and the installation environment. The internal moisture content will adjust to the surrounding atmosphere after the timber is installed and this may lead to permanent or seasonal swelling, splitting or shrinkage creating gaps at board edges. Exposure to sunlight, cooling, heating or other heat generating appliances is likely to cause localised shrinkage of timber that cannot be allowed for at the time of construction. This is to be taken into consideration when determining if there is defective workmanship. The assessment of the appearance of a floor is is to be carried out from a normal viewing position.

15.2 Timber flooring generally

Flooring, including tongue and groove strip flooring; structural plywood and particleboard sheet flooring, is defective if it is not installed according to AS 1684 and the manufacturer’s installation requirements. Colour variations due to natural causes such as sunlight are not defective. Ghosting, where blemishes appear beneath the finish coat, is defective when visible from a normal viewing position. Due to necessary machining tolerances, a step (lipping) of up to 0.5 mm or slight movement may exist between adjacent floor boards. This step (lippage) should not be evident at handover if the floorboards are also sanded and polished by the builder.

15.3 Gaps in exposed timber flooring

Except where affected by exposure to sunlight, cooling, heating or other heat generating appliances, flooring is defective if it has gaps of more than 2 mm
between adjacent boards that extend for more than 1 m, or more than 5 mm in total of three gaps between four consecutive boards.

15.4 Joint swelling in timber, plywood and particleboard flooring

Joints in plywood and particleboard floors are defective if they can be detected through normal floor coverings. Swelling in tongue and groove strip timber flooring is defective if it causes tenting, buckling or crowning of the boards and can be seen from a normal viewing position. Cupping in boards of more than 1 mm per 100 mm is a defect (Table C3 of AS2796.1).
Flooring with gaps that exceed the allowances stated above is not defective when the builder has made the owners aware in writing that the flooring system installed could suffer significant shrinkage and has obtained this acknowledgement from the owner in writing.

15.5 Nail popping in timber, plywood and particleboard floors.

Nail heads that can be detected through floor coverings or nail popping that is
clearly visible in exposed flooring are defective if they occur within 24 months
from handover.

15.6 Squeaking floors

Floors that consistently squeak by a person walking normally in a trafficable area within the first 24 months from handover are defective.

15.7 Springy floors

Floors that bounce in a way that can be detected by a person walking normally in a trafficable area are defective if the substructure has not been constructed in accordance with the Building Code of Australia and AS 1684.

15.8 Levelness of timber flooring

New floors are defective if within the first 24 months of handover they differ in level by more than 10 mm in any room or area, or more than 4 mm in any 2 m length. Also, the overall deviation of floor level to the entire building footprint shall not
exceed 20 mm within 24 months of handover. Refer to Item I of this Guide where the new floor is to adjoin an existing floor.

15.9 Splitting of timber decking

Splits in timber decking that extend to the end or side edge of the timber are defective if they are due to the fixing method. Owners who undertake their own floor polishing of exposed flooring or who lay floor coverings after
completion of the builder’s works are responsible to ensure that all nails and other fixings are properly punched or countersunk and stopped.

19.10 Floor Coverings

Carpets, vinyl and floating floor coverings are not prescribed under the HomeBuilding legislation in NSW but are subject to implied ACL (Australian Consumer Law) statutory warranties provisions. However, they often form part of the residential building contract and would be considered to be defective if not installed to the manufacturer’s installation instructions and a breach of implied statutory warranty provisions of ACL. Floating floors which rest on the structural floor are defective if not installed in accordance with the manufacturer’s installation requirements. Movement noises are an inherent characteristic of this type of flooring.


 full link  available at http://www.fairtrading.nsw.gov.au/biz_res/ftweb/pdfs/Tenants_and_home_owners/NSW_Guide_to_Standards_and_Tolerances.pdf


The subfloor dictates the long term performance of a floor covering. Even though the client often doesn’t see this stage of the job, it’s the part that most often causes problems.

Planeness: When a 2 metre long straightedge is placed on a concrete floor, resting on two points that are 2 metres apart, the maximum deviation from planeness (or ‘flatness’) is 4 mm.

Smoothness: When a 150 mm long straightedge is placed on a concrete floor, resting on two points, the maximum deviation is 1 mm.



Acoustic Ratings Summary

The National Construction Code (previously Building Code of Australia) requires floors between sole-occupancy units or a sole-occupancy unit from a plant room, lift shaft, stairway, public corridor, public lobby or the like, or parts of a difference classification, to have an impact sound insulation rating of not more Ln,w + CI = 62.
The floor systems that included the 2 mm polyethylene foam underlay were tested and the results are presented in Table 1 below.
Measured Floor Impact Insulation
Floor Systemmeasured Ln,Tw + CI NCC/BCA Requirement  NCC/BCA Compliance
Base Floor 66 + (-10) = 56 62Yes
8.3 mm timber floorboards*                     50 + ( 0 ) = 50                62           Yes
12.3 mm timber floorboards*                   53 + ( -2 ) = 51                62           Yes
14 mm bamboo floorboards*                    52 + ( 0 ) = 52                62            Yes
15 mm engineered timber                         52 + ( -1 ) = 51                62            Yes
veneer floorboards*
*Floating floorboards and underlay setup on top of base floor.
If the identical systems were installed in a Class 2, 3 or 9c building, they would comply with the NCC requirements. It should be noted that compliance was achieved by the floor/ceiling system as a whole. Varying any part of the system may result in a different impact sound insulation rating.



Slip rating


The moisture content (MC) of wood is expressed as a percentage.

This represents the weight of the water contained in the wood, compared with the weight of the whole body.

Moisture Content (MC) % =           weight of water           x 100
weight of wood substance

The fraction part gives you the proportion of water to wood fibre, and multiplying it by 100 converts the fraction into a percentage.

Coating systems explained

Over the last couple of decades, there has been a great deal of research into the coating products used as surface finishes on timber and cork floors.

Manufacturers have developed a wide range of products to cater for different types of floors and different performance requirements.

Each product has its own chemical composition and its own set of advantages and disadvantages.

Floor coating systems categories, are easily grouped by there composition;

  • oil-based finishes
  • composites
  • solvent-borne polyurethanes
  • water-borne polyurethanes.

Each category has products with surface finishes ranging from matt (or low sheen) up to gloss, and in the case of some polyurethanes, very high gloss.

There are varying Volatile Organic Compound (VOC) levels among the products within each category.


Oil-based finishes

Clients choose oils and waxes when they want a 'natural' look.

Curing oils are dissolved in mineral turpentine or white spirits and contain added curing agents called 'metal driers'.

Products include tung oil and linseed oil, which are generally cheaper than other coating systems.

These oils produce a rich timber colour, although they will darken with age, and in some areas may develop a yellowish hue.

They also require frequent maintenance with polishes.

Alkyds are based on curing oils, but are combined with a synthetic resin to improve their durability.

As a result, they require less maintenance than the curing oils.


The most common composite solutions are oil modified urethanes (OMUs), which combine an oil with urethane.

Products that have higher proportions of urethane have higher levels of durability.

The downside is that urethane also reduces the product's flexibility, which makes it prone to edge-bonding.

Most OMUs are solvent-borne and have high VOC emissions.

All OMUs tend to yellow with age. They also cure slowly in cold weather. But they are still quite popular because of their reasonable cost, good edge bonding resistance and intermediate durability.

Solvent-borne polyurethanes

If your client is looking for maximum durability and a high gloss sheen, solvent-borne polyurethanes will provide the best results of all coating products.

The main trade-off for their excellent performance is that they have a strong solvent smell and high toxicity levels while they're curing.

Two-pack systems tend to have higher isocyanate levels than one-pack products.

However, as long as the area is properly ventilated and you use an appropriate face mask, the health risks can be minimised.

Solvent-borne polyurethanes also have poorer edge-bonding resistance than other floor coating products, so you need to assess the floor before you start and advise the client if you think the boards might continue to shrink.

Water-borne polyurethanes

Water-borne polyurethanes come in a wide range of sub-categories, including acrylic and resin blends.

Products that don't contain acrylic provide a better wear resistance.

They come in two-pack or one-pack options and are available in matt through to gloss finishes.

The preferred choice of contractors and clients because they don't give off the strong smell.

They also provide a much better resistance to edge bonding.

The truth about acclimatising timber flooring.

If timber is acclimaties when it it not required it could have a departmental effect.

Firstly one needs to understand, what is moisture content, what is the relative humidity, and what part it plays in the overall stability of your floors.

The moisture content (MC%) is to the percentage of water contained within the timber to the over all mass.

The relative humidity (RH%) is the amount of water in the air as a percentage.

The other part of the equation is temperature. The temperature dictates the effect of moisture contained within the timber.

Most timber flooring in NSW are kiln dried to specific moisture contents according to species, and climate zone. The moisture content of the timber is determined by the average “relative humidity” and “temperature” of the in-service environment.

The RH% and average temperatures vary greatly around Australia, therefore the correct MC% in the timber will also need to vary to suit the different conditions in each area.

In a new construction there is no way to can control the environment inside, since generally there is no heating or cooling, no window coverings, doors are left open all day with tradesmen moving in and out of the house, etc. Basically you would be acclimatising to whatever the current weather conditions were at the time.

In a new build, most suppliers, installers & sales staff get confused on what's the right procedure, add to the mix, internet educated customers. In reality there is no way of knowing what the normal living conditions are going to be once the house is finished and occupied?

A Professional who have been in the trade for a long time will always do the right thing. The last thing they want is the job to return to a job.

In most cases if there is a problem with the floor it is due to a water leak or a major change in house in-service living environment from the time the floor was installed.

Taking readings of the MC of the timber and the RH and temperature until the correct equilibrium has been achieved, then and only then can the floor be installed.

So when to acclimatise the timber floor?  First, contrary to what you may have been told, it is bad practice to simply place the timber in the house for 2 to 4 weeks or to stack the timber in a room.

Timber floors in the right conditions do NOT grow in size or shrink; there must be a contributing factor and it always is related to moisture, either ingress into the timber or loss. Having a complete understanding of this will help you make the right decision when it comes to having your floors correctly installed.