The Complexity of Facades and the Risks Involved
In the last 10-15 years the building industry has gone through a multitude of changes which have impacted the role of facades and its growth in the construction industry. Some of these influences are driven by:
- Advances in manufacturing and material technology
- Pressure to reduce project duration by using different construction methods
- Environmental concerns
No longer consisting of simple building elements, modern facades utilise new materials in increasingly complex systems and these are being assembled in untested combinations with other modern methods of construction (MMC) as well as traditional wall types. Untested unique and bespoke building interface arrangements have an increased risk of one or more of their performance parameters failing.
Modern Methods of Construction: Risks
- More components
- More interfaces
- Less historic data / testing / familiarity
- More complexity of design and geometry
Unravelling the complexities of modern facades and ensuring that the facade is considered holistically rather than elementally has become a specialism, and facade consultants are now often required on many projects. The role of the Facade Consultant is to ensure that both the aesthetic and performance requirements of the façade are met during the design and installation stages. It is important that a facade consultant with the appropriate level of expertise and diversity of experience for the project is selected.
Finding a specialist contractor that can complete all elements of a facade is difficult, and in some cases impossible. As a consequence building envelopes are frequently divided up in to smaller packages. However, there comes a point when having too many specialist contractors becomes detrimental. Using a rainscreen wall as an example, we frequently see these packages being broken up into layers of, rainscreen and insulation, cement particle board, structural framing system (SFS), vapour control layer and plasterboard etc. with each layer being installed by different specialist contractors. This creates a multitude of conflicts and split design responsibilities within the 'standard' through wall element alone. Subsequently, these issues are multiplied several fold as soon as this construction hits an interface.
The short term savings generated by the splitting up of facade packages can quickly be eroded by extra management costs, site delays, additional costs from missed interface elements, etc. The risk of longer term (legacy) failures is rarely factored in when savings are tabled during the pre-construction phase; the 'cost to remediate' for legacy issues are many times more expensive than the original installation costs.
There are many reasons a facade can fail, all of which are avoidable, but to have any chance of mitigating failures the way that the specialist contractor packages are divided up needs to be carefully considered and it must be done giving due consideration to the capabilities of the specialist contractors that have been selected for tender.
Modern buildings are required to have much reduced air permeability, greater u-values and better waterproofing. To do this they rely heavily on gaskets, sealants, tapes and membranes. At junctions and interfaces it is critically important that these elements are detailed and installed correctly, and that the different specialist contractors co-ordinate their works.
When properly managed and designed, modern methods of construction can offer economic, rapid and robust solutions that were unobtainable with traditional methods.