Details
 

Researcher:	Alan Keiller  Richard Harris
Funded:	DETR PIT programme / industry
Total value:	£28,000
Lead partner:	CWCT
Status:	Completed

Background/justification:

As the principal barrier to weathering of the building the facade is subjected to the widest range of environmental variation. As the principal aesthetic element of the building the facade uses the widest range of dissimilar materials. For these reasons the durability of the facade is the most difficult to define, and the whole life cost of the facade the most difficult to assess.

Many of the materials used in facades interact chemically, both with each other and with the local environment. Standards for assessing the so-called 'long-term' behaviour of materials usually examine the effect of a single parameter upon one property of the material, and are usually based on simple specimens rather than the complex components that will be formed from the materials, and on readily achievable standardised test regimes rather than real-world conditions. Thus a piece of stainless steel may prove satisfactory in an accelerated corrosion test but will rapidly corrode when installed in a way that prevents regular cleaning of dirt from the surface, or a coating sample may pass a 1000 hour QUV test but give the designer no information about its expected life on a building in Birmingham.

There is a need to define a framework for assessing the durability of facades, as a function of the local environment, materials used, design methodology and installation practices. This framework can then be used to identify the need for new methods of assessment, and to give designers guidance on interpreting the results of so-called 'long term' behaviour tests. Although many of the factors affecting durability of facades and facade materials are already known they are widely spread throughout specialist literature. The approach taken in this scoping study will be to draw together this information into a single source, and to provide a single framework document for assessing the durability of facades. Reference will be made to relevant existing standards, and recommendations will be made for the preparation of new standards -standards directed at the needs of the designer and client, rather than the needs of the manufacturing industries as has previously been the case.
 

Objectives:

• Classify the range of environments achievable at the facade surface (e.g. UV, temperature range, pollutants)
• Classify materials used in facades (e.g. ferrous metals, non-ferrous metals, plastics, ceramics)
• Correlate known interactions between materials and environment (e.g. UV attack on polymers, alkali attack on ceramics)
• Summarise existing standards for testing material/material and material/environment interactions
• Cross-correlate known interactions with existing standards
• Identify need for new standards
• Generate framework for assessing durability of complex facades

Outputs:

One day workshop, 24 November 1998