Page 18 - Caswell Firesafe Manual 2018

TECHNICAL MANUAL

FFRDL / TM / BS / 01 / 2018

Fixings

The selection of the correct type of fixing is as critical as selecting the correct size of bearer and / or drop rod
for the support. Ultimately, failure of the fixings would lead to the collapse of the entire system.

Assistance can be obtained in the selection of fixings from reputable suppliers and, if required, pull tests can
be performed to verify the loads the fixings are capable of supporting.

As a general principle the following guidelines should be followed:

a) Fixings should be ALL steel. Plastic and Aluminium are NOT be used due to their low melting points

b) Minimum depth of penetration for anchors is 50mm for 2 hour systems and 60mm for 4 hour systems
c) Friction type fixings should NOT be used due to the risk of expansion

d) Spring Nut / Washer type fixings - as used in slotted channels - should NOT be used

e) Chemical type fixings ARE permitted provided they are fire rated for the same duration as the system

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A Schedule of approved fixings for use with CASWELL FIRESAFE ductwork systems is available on request.

It is necessary to establish the construction of the substrate to which the duct supports are to be attached prior
to specifying the fixings.

On new projects this information will be readily available from the Contractor. For existing building
refurbishments, what may appear to be solid concrete or block can in fact be hollow and as such it is critical
to establish this before installation commences. If there is any doubt whatsoever, it is strongly recommended
that test holes are drilled and “pull tests” undertaken to confirm suitability of a specific fixing type.

It should also be recognised that the element of building fabric (substrate) to which the support system is
attached must have a fire rating of at least that specified for the duct.

18 www.firesafeductwork.co.uk