Page 5 - Metal-Matters-issue-11

The case for metal roofs

Metal roofing systems contribute significantly to Both steel and aluminium can be reused or recycled Sheet metal systems coated with highly reflective Environmental challenges to reduce our carbon
the sustainable design concept thanks to their high repeatedly without losing their qualities as a building surfaces and designed with insulation and ventilation footprint have resulted in the need for integrated triple
recycled content, energy efficiency, low maintenance, material. The recovery infrastructure for metal can provide considerable cost savings for heating and skin rooflights and the requirement to specify highly
durability and recyclability which have all helped to recycling is highly developed and highly efficient, and cooling. Innovative cool roof coatings are now available thermal efficient insulation. These elements together
establish metal as the material of choice for both new has been in place for decades. Current recovery which have moderate to highly reflective surfaces over with the internal and external skin of the cladding must
and refurbishment roof construction. rates from demolition sites in the UK are 99 per cent a range of colours and some engineered coatings can be designed as an integrated assembly to achieve
for structural steelwork and 94 per cent for all metal increase the emissivity of the metal roof surface to the thermal requirements as set out in the Building
Steel and aluminium offer a better life cycle return construction products – figures that far exceed those allow solar energy and heat to dissipate quickly. Regulations. The design must also recognise the need
on investment than other materials. Today’s metal for any other construction material. for thermal isolation between the inner and outer skins
construction products are protected by highly Metal roofing has been used successfully for many plus thermal continuity at junctions and intersections.
durable paints and coatings that ensure a service life When metal is specified for a building, it is unlikely to years on industrial and commercial buildings but
in excess of 40 years. Steel construction is efficient become waste. Steel and aluminium always have a the demands put on it by modern architecture and The design phase calculations for thermal performance
and competitive; buildings can be rapidly constructed value and are only ever sent to landfill as a last resort. sustainability requirements have set new challenges. using the National Calculation Methodology which
using steel-based primary and secondary Waste generation is one of the least sustainable The roof profile, whether it is made from steel or uses the SBEM software provides the designer with
components that are efficiently manufactured off- aspects of construction. Choosing a metal-framed aluminium, not only has to provide a weatherproof an opportunity to accept general psi and alpha values
site and therefore are dimensionally accurate and of building is the simplest and most effective way skin but it also has to provide structural strength to for the construction detail or enhanced values which
known quality. to reduce waste. Even during manufacture and accommodate imposed and service loads throughout are system specific. These system specific values
fabrication, any swarf or offcuts are recovered and the construction phase and operational phase. are available from the individual profiler or system
Steel framing and metal cladding systems provide the recycled back through the primary Increasingly it has to serve as a working platform supplier but the on-site construction must reflect the
scope, in association with other materials, to design production process. or access way for maintenance of photovoltaic (PV) design assumptions. Design detailing is also important
buildings with low overall environmental impacts. arrays. The aesthetic service life of the profiled metal to minimise air permeability at junctions between
Steel-based construction systems provide flexible Metal has much to offer in the areas of green sheeting has also got to be considered at the design elevations and intersection with other materials or
spaces which have the potential to be easily modified technology and sustainability and MCRMA members phase because it can have a strategic effect on systems. This should form part of the overall design
and adapted so that the life of the building can be are at the forefront of developing innovative solutions the in-service life of the system and the long term philosophy and should not be subject to compromise
extended by accommodating changes in use, layout for example, green roofing systems that can improve sustainable solutions. at the design, installation or commissioning phase.
and size. the thermal performance of a building by providing
protection against heat loss in the winter and heat
gain in the summer.

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