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Natural Timber is hygroscopic; that is, it continually takes up
and gives off moisture to keep in balance with its surroundings.
This results in a process of natural shrinkage and expansion.
Because of this, a 'perfect' (continuous mirror finish) is not
practically achievable and gaps between boards are inevitable as
they accommodate the seasonal change.
Depending on the timber species chosen, visible shrinkage and / or
expansion may take a day, a week or even months, resulting in the
gaps between floor boards opening and closing depending upon the
weather, the season and local influences.
To reduce the degree of shrinkage and expansion, today's Timber
Flooring should be seasoned for stabilization and kiln dried to
average moisture content between 9% and 14%.
This is considered to be a good starting point for the majority of
installations, but as you will read later, many other factors
influence the atmospheric content around and in your home and
therefore affect your floor.
Which Timber to Choose
Choosing the right floor for your home will probably be the most
difficult step, only because of the huge selection from which you
can choose.
The following information will assist you to understand the
alternatives and help you ask the right questions when discussing
the various options with your supplier.
Timber Colour
This is purely a personal and aesthetic choice. The timber species
will determine the general color, however, even within one species
there will be natural variations. Some species exhibit only small
variations while others vary greatly in color and feature.
Remember timber is a natural product and no matter how big a
sample you have seen your floor will be different from the sample
and completely unique. The true colour of the floor will only
become evident after it has been sanded and coated with your
chosen finish.
Darker timber could make the room appear darker, and may therefore
require more available daylight and/or artificial light sources.
Appearance of coated floors will mature with age.
Timber Hardness
You may also consider the hardness of the timber if you expect
exceptionally heavy traffic or stiletto heels. Australian species
vary from 3.5 to 14 on the scale.
Timber
characteristics and density vary. Refer to Australian Hardwoods
table.
Remember the durability of your surface coating will determine the
wear expectancy of your floor.
Timber Features and Grades
Depending upon the species chosen, various grades may be
available. You may prefer a grade which exhibits the maximum
variety of natural features including colour, knots, gum vein
(generally dark lines) and insect markings to provide a unique
visual impact. In our kiln dried species this is Standard, Feature
or Rustic Grade, or you may prefer a mix, which offers maximum
achievable consistency, this is described as "Select” grade.
Be sure to discuss the natural feature variation encountered in
your chosen species and also the available options with your
supplier.
The Australian Standard refers to grades as Select – Standard –
Cover. Clarification must be sought when purchasing timber from a
supplier that uses marketing names for various mixing of grades.
There can be considerable price variation between the grades.
Board Width and Length
Tongue and Groove flooring is generally supplied in random lengths
from about 1m to 5.4m. Universal profile of 60mm, 80mm, 85mm or
130mm (actual cover width). The width of boards and the direction
they are laid will affect the look of a room. Generally boards
laid along a room will make the room look longer while the boards
laid across a room will make it look wider.
Other factors such as the sub-floor materials may control the
direction the boards must be laid. The wider the floor board the
greater the natural shrinkage / expansion across the face.
Therefore, during dry periods, wider boards may exhibit slightly
wider gaps between the boards and cupping may also be more
apparent. Both of these conditions may generally disappear after a
reasonable period of normal humidity / weather conditions.
Top (face) Nail or Secret Nail
Some species and board widths are offered in a choice of top nail
or secret nail profiles. As the name describes, top nail profiles
are installed with nails through the top surface, while secret
nail profiles are installed with nails through the tongue, and are
thus hidden by the adjoining board. Face nails at the start and
finish points complement secret nailing. If attempting secret
nailing direct to joists, advice should be sought. 85mm is the
maximum to secret nail, wider boards must be top nailed.
System
Development
NSTF has developed a flooring system that can be successfully
glued direct to concrete and is available in 80mm, and 85mm widths
with thickness of 19mm. The species available are Tasmanian Oak,
Southern Oak, Blackbutt, Spotted Gum and Grey Gum.
Home Design Considerations
Shrinkage and expansion of timber board floors is natural and
cyclical process. The degree of movement depends on the
surrounding changes in atmospheric moisture content and therefore
is generally controlled by the seasonal weather conditions.
Changes are most evident during long periods of dry or wet weather
conditions however, local conditions also have considerable
influence.
Good ventilation under your floor is a very significant factor in
a successful installation. Minimum ventilation recommendations may
not be adequate for your site. Excessive humidity in the
under-floor area can be caused by the lack of sufficient
cross-ventilation or from damp soil conditions arising from poor
drainage. Ensure the water from gardens or storm water does not
drain under the floor area and that no water lies in the under-the
house.
Air conditioning and heating systems dramatically reduce the
general moisture content within a house. Your flooring specialist
should be made aware that these systems are to be used. It may be
necessary or advisable during laying / coating to operate these
systems and to acclimatise the flooring to the average conditions
in these circumstances.
Shutting up a house when away on holiday for long periods can also
create abnormal conditions. Full-length windows, large glass areas
and skylights, which admit direct sunlight, can create sunroom
conditions and with high temperatures and low moisture conditions,
cause floors to shrink. Direct sunlight will also cause colour
changes to the timber, so moving rugs occasionally, and the use of
curtains and blinds is a good idea.
If your home is located close to the body of the water such as the
ocean, a river, large dam or wet lands, or if it will experience
prevailing winds which may direct particularly moist or dry air
towards your home, special moisture control measures may be
required. Expert advice should be sought.
Transport and On-site Storage
It is most important to ensure a suitable on-site storage location
is available before delivery is arranged as incorrect storage will
damage the timber and / or delay laying. All flooring timbers
should be protected from the elements during loading,
transportation and unloading.
The optimum storage location is under cover, protected from the
elements and direct sun and where the atmospheric content is
similar to the level expected in your home.
In all locations a timber pack should be stored at least 200mm off
the ground / concrete, with even supports to maintain straight
boards and to allow good ventilation to all pack faces. A moisture
barrier like poly sheet between the ground / concrete floor and
the underside of the timber is essential.
Do not store timber
in it’s plastic wrapping exposed to direct sun as this limits air
circulation and exposes the timber to extremely high temperatures
which causes sweating.
Do not store timber on a fresh concrete floor or in a recently
rendered room, as the timber will absorb moisture from the drying
concrete.
Installation and Acclimatisation
Depending upon the situation it may be necessary or advisable to
acclimatise the flooring to its proposed location prior to fixing.
It is not advisable to fix acclimatised timber flooring during or
just after extended periods of wet or dry weather. In this case,
allow a period of normal weather conditions before commencement.
It is preferable to lay flooring only after all "wet trades" such
as brick cleaning, rendering, plastering and tiling have finished.
Plastic laid over the floor to protect it from the wet trades
often raises the moisture content of the flooring timber and can
be counter productive. Close monitoring is required in this
situation. Ensure expansion gaps of 10mm to 12mm are left between
boards and the wall. These are usually covered by skirting boards
or filled with cork strip or by small bead of timber. Before
fixing, ensure that your contractor has checked the flooring
moisture content.
The need for on site acclimatisation will be minimal if correct
production, handling and storage procedures are followed prior to
the flooring arriving on site.
Installation procedures and recommendations in regard to "cut in"
floors and platform construction are well described in Timber
Queensland Technical Data Sheet 11. Platform floors are not
recommended but if this process is used, the timber flooring
should be coated with an appropriate sealer, which is compatible
for the floor finisher's products.
For Further
Considerations Click Here For Timber Flooring Data Sheets
Compiled by Robert Clague of Northern Suburbs Timber Flooring Pty
Ltd from literature available from Flooring Manufacturers TQ,
the appropriate Australian Standards and our own Quality Assurance
presentation for Installation and Supply specifications to assist
intending purchasers of timber flooring.
Disclaimer: The information in these procedures is distributed on
an “as is” basis, without warranty. While every effort has been
made to ensure that the information is free from errors and
omissions neither the principals of Northern Suburbs Timber
Flooring Pty Ltd or their respective employees and agents shall
have any liability to any person or entity with respect to any
liability, loss or damage caused or alleged to have been caused
directly or indirectly by advice or instructions contained in this
information described herein. Readers are urged to seek prior
advice before making decisions based on information as to colours
of timbers, floor finishes and their expected life.
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