Technical News

Our technical news section describes the conclusions of technical issues that have been discussed within the CWCT Technical Committee. Note: The conclusions reached were made based on the best available knowledge at the time. We welcome your comments and feedback on these issues. If you would like to get in touch, please email us.

The use of magnesium oxide (MgO) boards

In high humidity conditions MgO boards can suffer from sweating/leaching releasing chloride which can cause corrosion of metal components, particularly fixings, in contact with the board. There have also been reports of timber in contact with the board being adversely affected.

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Clarification of TU21 requirement for dynamic watertightness testing

TU21 states that a dynamic watertightness test is required when the wind load exceeds 1800Pa. A query has been raised whether this is the positive wind load or the greater of the negative and positive pressures. 

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Pretreatments for powder coating on architectural aluminium

This note summarises the current changes affecting the specification of powder coatings on architectural aluminium and provides interim information for specifiers.

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Following the tragic events at Grenfell Tower last month, focus is now turning to how the industry responds to the challenges ahead. This includes short term concerns such as ensuring that current buildings are safe, and longer term issues such as revisions to the Building Regulations.

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Revised method of heat soaking toughened glass

A revision of BS EN 14179 Glass in building - Heat soaked thermally toughened soda lime silicate safety glass Part 1 Definition and description was issued in August 2016. The most significant change is to the temperature regime for the heat soaking process.

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Revised European curtain wall product standard BS EN 13830:2015

Although this Standard has been published by BSI, it has not been approved by all the relevant European committees and therefore is not currently valid for CE marking.

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CE marking of curtain wall brackets

CWCT has received enquiries about the need to CE mark curtain wall brackets in accordance with EN 1090 as they can be considered structural products.

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Deflection of glazing in windows and curtain walls

There are no established limits on the deflection of glass used in windows and curtain walls.

The only clear requirement to limit deflection of glass in British Standards is given in BS 6180, which limits the displacement of glass in barriers to 25mm. This displacement would include any movement of the support to the glass.

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