ROOFING & CLADDING
SR Timber’s trading director, Shaun Revill, looks at the impact of BS5534:2014 on timber roofing batten.
When it was launched, British
Standard BS5534:2014 – which
set out a new code of practice on
slating and tiling for pitched roofs
and vertical tiling – was welcomed with open arms
by some, accepted by most and begrudged by a
few. There’s one thing nobody can deny – it was,
and remains, a game-changer for the industry.
Before we look specifically at the impact it’s had
on batten, it’s worth reminding ourselves of the
key areas that the standard covers:
1. Fixing specifications
The introduction of the Structural Eurocodes has
seen greater emphasis placed on the calculation of
wind speeds as part of pitched roof construction.
All single-lap tiles should be mechanically fixed
using a clip, a nail or a combination of both. And
double-lap plain tiles and slates used in exposed
areas may require enhanced mechanical fixings in
the form of stainless steel nails or screws.
Vapour resistance and resistance to wind uplift
are the two key factors when selecting underlay,
as stricter recommendations for the securement
42 BUILDING PRODUCTS | APRIL 2018
of the laps of the underlay and a new labelling
system have been introduced. Only underlays
suitably labelled and meeting the new standard
should be installed. Fixing penetrations through
the underlay should not be subject to enlargement
caused by shrinkage or nail tear as a result of wind
uplift loading and they should be sealed where
required, to prevent water ingress.
Mortar is now deemed to have no tensile strength,
so any tensile bond strength offered by the mortar
bedding of concrete or clay ridge, ridged hip, verge
and valley tiles should not be taken into account
when determining the mechanical resistance
required to resist wind uplift. All mortar-bedded
components should be supplemented by
mechanical fixings to secure them to the roof
structure where the wind uplift load exceeds the
dead load resistance.
4. Timber roofing battens
The standard clarified the rules around the
quality of materials, the grading of batten and
the documentation that accompanies it. During
production, roofing battens are piece stamped