SmartFrame Subfloor 2011.pdf - Tilling Timber

GENERAL INFORMATION - ABOUT FLOOR PERFORMANCE
The “feeling” that is identified when a person walks on a floor
is very subjective. Some people want to feel a very stiff floor
and others want some ”give” so that it softens the footing.
When people say the floor “bounces”, it may be vibrating.
This sensation is often caused by lack of dead load such as
furniture, direct applied ceilings or other materials to absorb
or dampen the vibration.
The allowable spans shown in the tables of this manual have
been designed to meet the strength and serviceability
criteria in AS1684.1 .
FACTORS THAT CAN AFFECT FLOOR
DYNAMIC PERFORMANCE.
• The choice of flooring system
• The depth, stiffness and mass of the joists
• Spacing of joists
• Fixing of sheathing to joists
• Stiffness and mass of floor sheathing
• Mass and stiffness of ceiling materials
• Method of installation
• Location and type of internal partitions and furniture
FACTORS THAT CAN IMPROVE FLOOR
DYNAMIC PERFORMANCE
Glue-nailed floors will perform better than floors
secured by nails alone.
Deflection of the sheathing material between joists can
be reduced by decreasing the joist spacing or using a
thicker and/or stiffer sheathing.
Proper installation is essential for dependable
performance. Adequate and level support for the joists
is necessary, as is correct fastening of the joists and
sheathing.
The installation of a ceiling to the bottom flange of the
joists.
Between joist blocking can provide some improvement
to floor dynamic performance. It is emphasised that for
between joist blocking to be effective, it is important
that the blocking is continuous, this being easily
achieved by the addition of a continuous bottom strap
such as hoop iron strapping which is also attached to
the end walls.
If floor dynamic performance is a concern to either the
client, designer or contractor, then the above variables can
be altered to improve dynamic performance. Some stiff
floors with very little dead load may tend to vibrate. This can
generally be dampened by directly attaching the ceiling
below the underside of the joists. Where there is no lining to
the underside of the joists, it is recommended that between
joist blocking be utilised to dampen this lightweight floor.
If between joist blocking is to be used to improve floor
dynamic performance, it is recommended that a blocking
system (at least midspan, 1/3 points for large open rooms)
similar to the one shown below should be adopted:
BETWEEN JOIST BLOCKING FOR SmartJoists
Floor sheeting glued AND nailed
to joists and blocking
SmartJoist between joist blocking,
skew nailed with 2.8 x 60 mm nails.
0.91 x 25 mm galvanised mild steel strap
fastened to joists, blocking panels and END
WALLS with 40 x 2.5 mm galvanised nails.
SmartJoist
floor joists
DEEP JOIST BLOCKING OF SmartLVL
AND TEMPORARY SUPPORT TO PREVENT
JOIST ROLLOVER DURING
CONSTRUCTION
D
W
End trimmer to
all cantilever
joists
Temporary restraint
to link top edge of
joists during
construction
W
Temporary restraint to
link top edge of joists
during construction
D
3.6 metre maximum spacing of blocking
pairs with temporary top edge restraint
Additional temporary restraint
to link top edge of joists and
blocking pairs at a maximum
of 3.6 m centres during
construction for joists
with D/B > 6
SmartFrame Sub-floor Design Guide 3