The Interspan flooring system consists of 200mm wide precast
prestressed concrete ribs spaced generally at 900mm centres with
timber infills placed between them. The ribs have variable depth
to suit the projects load/span requirements. This multi piece
system is tied together with a 75mm insitu concrete topping and
mesh reinforcing. This system has the benefit of being suitable
for those tricky sites where access is a problem or poor
foundation conditions dictate the use of a comparatively
Interspan is easily adapted to circular floor plans, where
the use of other suspended flooring systems is difficult. Large
floor openings of up to 700mm between ribs are easily
Timber infill planks are merchant grade rough sawn timber.
Timber infills should be dampened prior to placing the concrete
topping. Alternative timber types can be left with an exposed
underside finish to create an architectural feature, e.g.
polyurethaned macrocarpa or rimu.
One of the major features of a concrete floor is the low
sound transmission. The table below shows sound transmission
ratings achieved by Interspan.
Interspan Ribs must be handled and stacked at two points, at,
or directly beside the lifting eyes.
It is recommended that Interspan ribs be ideally seated 75mm
onto the supporting walls/beams, and bedded on wet mortar, vinyl
or plastic bearing strips to ensure an even bearing at the
correct level. Less than 75mm seating may be used in
consultation with Stresscrete.
FIRE RESISTANCE RATING
Standard Interspan provides a 1 hour fire resistance rating.
An increased fire rating can be achieved with specific design.
ALTERNATIVE FLOORING SYSTEMS
Hollowcore and Double Tee’s, are available for longer spans,
and/or heavier loads.
Rib Strength= 42 MPa at 28 days Topping strength = 20 MPa
minimum at 28 days
Topping thickness =75mm
Propping = from 1-4 props
Rib centres = 900mm
Fire rating 60 minutes
FURTHER TECHNICAL INFORMATION
Specifications for the manufacture, transport and erection of
Interspan, and standard details for typical situations, are
available from your nearest Stresscrete branch. Experienced and
qualified staff will be pleased to discuss design and fixing
details. Refer general notes.