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How has the cladding crisis happened?

19 June 2023

This article explains how the cladding crisis began and delves into the industry point of view in 2010 which led to the building regulations being mis-used. 

Imagine you are the owner of a high rise residential building in 2010. The building was built in the 1970's using precast concrete floors and walls, with metal frame windows, perhaps even with a single pane of glass. The thermal performance of the building was terrible, using excessive energy to keep warm in winter, with condensation causing damp and mould. 

Your tenants are unhappy, your fuel bills are destroying profits and the only solution seems to be to relocate tenants, knock it down and rebuild, which would require enormous investment.

Then you learn of another option; construction workers are able to enclose the building in new, high-performance materials such as rigid foam insulation and weatherproof, colourful and durable cladding panels. New, thermally efficient double glazed windows can also be set within the new cladding overcoat, resulting in a building that looks brand new. Yes, this will cost a significant amount, but much less than a full rebuild. Tenants can stay in the building throughout, continuing to pay rent, with the promise of increased comfort. 

You assemble a design team who are able to produce construction information and advise you on how to procure the work. The sage advice is to use a form of contract that allocates the responsibility for the design and delivery onto one main contractor. This main contractor will then recruit designers and specialist subcontractors, including a consultant to ensure the project complies with the Building Regulations known as the approved inspector (AI). This is much better than the traditional type of contract where, as the employer, you would share the risk of project problems. 

The project is tendered to the market and the sensible thing to do is to appoint the lowest price contractor, it may even be a fixed-price, providing you and your financiers with a minimal risk, lowest cost solution. 

The first thing your new main contractor will want to do is to value engineer the project. In theory, value engineering is a way of rethinking the design to optimise the ratio of function to cost. Ideally, this cost would be over the whole-life of the asset. In practice, the contractor will only be involved for the construction phase and will not benefit from any whole-life benefits, some of which may require an increased construction cost to obtain. 

The contractor has already committed to a fixed cost, so is incentivised to cut cost from the original design to maximise contingency, or profit. How much cost can the contractor trim? That depends on the designers accepting a reduced performance, quality, or aesthetic. You as the employer may not have much say in this process, as when you off-loaded your risk on to the contractor, you also allowed them to alter the quality of your project. 

In the value engineering meeting, each item is referred to the AI to check it will still comply with the regulations. If it complies, the costs can be saved. The process has become a bit of a game, to see how much cost can be saved while still achieving minimal compliance. 

Reading this now, it is clear that this practice is not how the regulations were intended to be used, but (almost) everyone was doing it in 2010. The AI wanted to win more work with the main contractor, so they would look for ways to further reduce cost while still complying. A common theme arose regarding the compliance of cladding materials. For the proposed building to use a non-traditional walling type, it was known that these new lightweight materials would not be as robust in a fire as traditional bricks and concrete would be. So to assess their fire performance, they would be built in a test facility and set on fire, hoping to resist fire spread for the required period of time to allow safe evacuation. The results from this empirical testing could then be used to demonstrate compliance on an equivalent building. This means that every refurbishment project did not have to incur the cost of a cladding fire test. 

Another way to save cost was to only have one escape stair within the building. Normally two stairs would ensure safe evacuation if one stair was blocked by fire. However, a stair occupied potential lettable area from each floor and if each apartment had sufficient fire protection, the occupants could remail safe in their apartment while the fire was fought. Therefore, one escape stair became the norm.

Design information for the 'value engineered' design would then be produced for the construction teams. Given that the design used new materials and techniques, the subtleties of the compliance requirements were not clearly passed on to the respective installers. The designers involved in the value engineering may not have been retained during the construction phase, in order to explain how the design was supposed to work. This resulted in cladding contractors, working at height and exposed to the changeable British weather, not installing items correctly. Over-cladding a building, involved fixing a metal or timber frame to the original wall, to hang the cladding panels on. The gap (cavity) created by the frame needed to be closed, so that if a fire in one apartment broke out of a window, it couldn't use the cavity to travel to the window of the apartment above. 

Cavity barriers were required around openings, such as windows, vents and on the compartment lines between apartments. However, if the cladding cavity was fully closed, it would prevent the escape of moisture, leading to damp and mould. So active cavity barriers were installed in a compressed state, allowing the cavity to ventilate, but in the heat of a fire they would expand and close the cavity, preventing the spread of fire. 

The placement of active cavity barriers against the cladding was critical. They must be fixed so that the fixing does not prevent expansion and be the correct distance from the cladding, or they would not close the cavity. 

We now know from inspecting hundreds of buildings that installers did not know how to use the products correctly. AI's did not check every cavity barrier and often, did not check at all. 

Post Grenfell, lenders needed a way of understanding the building's fire safety so the RICS developed the EWS1 form that would apply a risk rating to the building. The form required an inspection and the inspections revealed significant problems. We are now seeing an abundance of warranty claims and legal actions that seek to test new provisions within the Building Safety Act 2022. 

Much will be written about where this journey leads, but hopefully the above explains part of how it started. 

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