Colorcoat® Column: Gauges

What impact does the ordered gauge have on the structural performance of profiled pre-finished steel cladding?

The structural performance of a pre-finished steel profiled sheet is dependant upon 3 factors:
1.shape/geometry of the profile
2.gauge of the steel substrate
3.mechanical properties of the steel grade used.

Gauges and tolerances

EN10143:2006 specifies the maximum and minimum actual gauge, which is permissible for a nominal ordered gauge.
For example a 1250 mm wide 0.7 mm coil must be supplied within the gauge range 0.64 mm to 0.76 mm.
It should be noted that the tolerances quoted in the current 2006 version of this document are slightly tighter than those quoted in the previous document, so the specifier should ensure that material is supplied to the correct standard.
Ordering material with a lighter nominal gauge than 0.7 mm, but within the apparent tolerance range, may result in material actually produced being less than 0.64mm. The structural performance of the profile will consequently be reduced.
All Colorcoat® pre-finished steel meets the requirements of EN10143:2006.

Mechanical properties of the steel substrate

All Colorcoat® pre-finished steel for wall and roof cladding is supplied with a specified minimum yield strength. This figure is used to calculate the structural performance of the profiled pre-finished steel sheet. In practice, the actual yield point will generally be significantly greater than the minimum value, resulting in a profiled pre-finished steel sheet with a greater resistance to stress failure.

 “How do I ensure the correct structural performance of the pre-finished steel sheeting?”

Load span tablesLoad span tables are used to calculate the maximum permissible purlin spacing at which the profiled sheeting will meet the structural requirements for the building location and application.
All Corus Colors supply chain partners have load span tables that have been calculated according to EC3 and have been independently assessed and approved by the Steel Construction Institute. (SCI Assessed)
The load/spans quoted in these tables are specific to the exact profiles and material specifications supplied by these profilers and cannot be applied to different profiles or material grades/gauges.

 

CE marking

CE-marking is a European product information label that indicates that the properties of the product have been tested according to European standards. The European Commission has determined which properties for which building products in the EU are relevant and should be tested and what external verification is appropriate.  The values of the tested properties have to be stated/printed by the producer on the product, the packaging or the accompanying coupon. Country supervisors inspect randomly if CE-marks on products are complete and correct.
All Corus Colors supply chain partners are able to supply CE marked pre-finished steel profiled sheeting, which meets the requirements of EN 14782.

Eye-catching façade for Milan Design Week

Qbiss by trimo using Corus Colorcoat Prisma® was instrumental in the successful delivery of The Dolls House – a striking architectural installation created by Slovenian designer Nika Zupanc that greeted visitors as they entered the Superstudio Piu at Milan Design Week.

Forming part of the exhibition, I Will Buy the Flowers Myself, the concept behind The Dolls House innovative design, with its chimney and pearlescent smoke, was to represent the difference between the world of objects and the world of forms encapsulated in the image of a house.  Key to the successful delivery of Nika Zupanc’s design was the need to achieve a finished structure whose ‘chic and elegant surface [used] deep colour [to create an] almost 3D effect.’

The design demonstrates Qbiss by trimo’s new modular façade system which defines the standard for the modern building envelope; a complete modular facade system combining all the very highest aesthetics together with the form and function demanded by today’s architects and designers. This makes it a perfect system to use Corus Colorcoat Prisma® pre-finished steel.

Erhan Ozdemir from Corus Colors comments:  “Corus Colors is committed to enabling cutting-edge contemporary architecture through enhanced understanding of materials, so we were delighted to be involved in The Dolls House which is a fantastic showcase for how the innovative use of steel can play a fundamental role in the delivery of innovative modern design.”

Erhan continues:  “The use of colour and form were key to the success of this conceptual architectural installation due to the dramatic impact required for the final appearance of the building. Colorcoat Prisma® is a high-performance pre-finished steel with superior aesthetic appeal and, as such, was the ideal choice for the eye-catching architectural installation as it enabled the designer to deliver a colour solution that would realise the minimalistic and avant-garde specifications of the design brief whilst also ensuring the structure’s visual appeal. In addition, it provides optimised Galvalloy® metallic substrate for ultimate corrosion resistance

Colorcoat Prisma® is available in wide range of colours and specifiers can also take advantage of a bespoke colour matching service to create a tailored look for any building. A robust and durable product that provides excellent durability. Furthermore it provides outstanding colour and gloss retention fully backed up with the comprehensive Confidex® Guarantee of up to 25 years to provide total peace of mind.

Click here to view the case study and gallery on colorcoat-online.

Colorcoat® Column: Overpainting

With the onset of summer many building owners may decide that there is a need to refurbish their building and one method they may wish to undertake is to over-paint. Here are a few queries we often get with regards to over-painting.

 

What is the preparation required prior to over-painting ?

This will depend on the condition of the existing cladding, which there are three main types:

1. Colour change e.g. change of ownership of building and a requirement for new colour scheme.

This in many cases will mean only thoroughly washing down with a suitable detergent/water solution to remove all dirt, grease and deleterious matter and fresh water rinse. New Plastisol surfaces may need to be wiped with white spirits before washing

2. Paint weathered but still sound to substrate.

Areas of algae growth should be treated with a proprietary fungicidal solution (use as per manufacturers instructions) to sterilise surfaces. This must be done prior to washing which must be thorough to remove all dirt, chalk deposits, oil, grease, residues from sterilisation and any other deleterious matter. Fresh water rinse and allow to dry. If there are any areas that have corroded remove corrosion with abrasive tools back to bright metal and feathering to sound paint

3. The original coating is very old and delaminating.

All existing coating removed back to the metallic substrate by a suitable means. These can include Chemical Stripper – use as per manufacturers instructions Abrasive Blast Cleaning – wet or dry blast clean in accordance with equipment manufacturer’s recommendations High Pressure Water Equipment With all methods you must ensure all surfaces are thoroughly clean before application of any paint. I would point out that before commencing with removing of coating and over-painting you may which to price a re-cladding of building, which often proves to be a cheaper alternative.

How is paint applied and when?

There are paint systems available that can be spray, roller or brush applied. Application technique should ensure that an even wet film is applied to surface at a thickness as recommended by paint manufacturer. If brush applied an appropriate brush size for cladding profile should be chosen. When spraying, ensure all site restrictions are considered and areas not to be treated should be protected or adequately masked up. Application should be carried out in weather conducive to painting, obviously not in heavy rain or strong winds if spraying. Otherwise problems such as rain spotting, pinholing, blisters or blooming etc. can occur.

What paint system should I use?

There are many manufacturers systems that are compatible with our coating systems and choosing the right coating for over-painting is important. Using a high performance, water-based paint can reduce the amount of Volatile Organic Compounds (VOCs) liberated during the over-painting operation compared with conventional solvent based paint. However, water-based systems can sometimes be restricted by weather conditions i.e. rain

Colorcoat® Column: Marine Environments

Question When specifying cladding systems for the construction of a building envelope in a marine environment what material would be best? Would it be aluminium?

Answer  Firstly we should define what we class as a marine environment. Under the Corus Confidex® Guarantee (available only with Corus Colorcoat Prisma® and Colorcoat HPS200® Ultra) it is classed as a building that is within 1 km from any coast. Generally aluminium is tolerant of PH values between 4.0 and 8.5 at room temperatures forming a film of hydrated aluminium oxide on the surface. A saline environment could mean a risky environment for the use of mill finished aluminium. A marine environment can cause pitting to the aluminium surface. The severity of this pitting obviously is dependant on how aggressive the environment it is subjected to. Therefore it is often recommended that painted aluminium be specified. The most common paint employed to coat aluminium is PVDF.

We at Corus do not recommend the use of PVDF on zinc coated steel substrate in marine environments as they offer markedly inferior performance. This is due to inherent coating permeability, which can lead to under film corrosion of the zinc and causes paint blistering particularly in stressed areas such as profiled bends.

Corus recommends that in saline environments a high build protective system such that is offered by Colorcoat HPS200® Ultra. The 200 microns thickness provides a more effective barrier against the permeation by salt polluted moisture than thinner coatings such as PVDF (27 microns thick). Furthermore, the excellent damage resistance of Colorcoat HPS200® Ultra is of particular advantage where a potentially aggressive atmosphere can readily attack steel substrate exposed due to physical damage.

Usually performance figures for PVDF coated aluminium when used in marine environments are in the range of 15 years. Corus offers a Confidex® Guarantee of up to 30 years for roof and wall on Colorcoat HPS200® Ultra. Euronorm 10169-2 outlines requirements for the corrosion resistance of pre-finished steels. The most onerous category, RC5, requires products to resist blistering, coating damage and edge delamination <2mm when exposed to aggressive industrial and marine environments. The unique Galvalloy® metallic substrate from Corus and step change in paint formulation that has been developed for Colorcoat HPS200® Ultra mean that it can easily meet this very high standard.

New BREEAM Technical Paper

Corus has announced the publication of a new technical paper – ‘An Introduction to BREEAM for pre-finished steel industrial buildings’ – which takes an in-depth look at this environmental assessment method, and provides specifiers, building owners and clients with a comprehensive understanding of the benefits of having industrial buildings assessed within the BREEAM scheme.

BREEAM (Building Research Establishment’s Environmental Assessment Method) is the UK’s leading and most widely used environmental assessment for buildings. Developed in the early 1990s, it is based on many years of construction and environmental research and is validated by input from the construction and property industries, the government and building regulators.

The BREEAM scheme is used to assess the environmental impacts arising as a result of an individual development at the design and post-construction stages.  The post-construction review serves to confirm the interim assessment (done at the design stage) and, most importantly, that the ‘as built’ performance matches that envisaged at the design stage.

Corus’ technical paper focuses on how to achieve BREEAM ratings for industrial buildings. It also demonstrates how the incorporation of Colorcoat® pre-finished steel into the specification for both roof and wall cladding systems can maximise the credits assessed under the energy, materials and waste categories.

The sustainable attributes of pre-finished steel  roof and wall cladding systems can contribute to achieving a good overall BREEAM score, and given the synergy of pre-finished steel building envelopes with a structural steel frame  (which is also highly regarded under BREEAM) the case for steel is clear.

Carlton Jones, Technical Development Manager of UK Construction at Corus Colors, comments: “The purpose of this paper is to give a clear overview of what BREEAM is and how it is assessed as well as providing guidance on how to achieve its ratings. Corus has a well-established reputation for providing specifiers with comprehensive advice and guidance to support the design and construction of the pre-finished steel building envelope. Working together with the Steel Construction Institute (SCI) we have endeavoured to explain BREEAM and how the specification of the building envelope forms an important part of the key issues that can contribute to a good BREEAM score.”

Click here to download the paper