Approved Document B 2019 – What are the requirements for external walls on high rise buildings?

13 December 2019 Kingspan Insulation UK
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In the summer of 2019, the Ministry of Housing, Communities & Local Government published a revised version of Approved Document B in England (ADB-2019). This is an official technical guidance document which accompanies the Building Regulations and sets out how building work must be completed to achieve compliance with fire safety regulations. 

In this blog, we take a look at what has changed and how this may impact external wall specifications on buildings with a storey 18 metres, or more, above ground level.

Relevant Buildings

Before we get to ADB-2019, it is important to highlight the updates made to the Building Regulations at the close of 2018 and, in particular, Regulation 7(4). This regulation sets out what is considered a “relevant building”. 

In the Regulation, a “relevant building” is described as one which has a storey at least 18 metres from ground level and contains:
•    one or more dwelling;
•    an institution; or
•    a room for residential purposes (excluding any room in hostels, hotels or boarding houses). 

With some exemptions stated in Regulation 7(3), materials installed as part of the external wall, including insulation and specified attachments such as balconies (an attachment to a wall, unheated on both sides, including attached and inset balconies), must now achieve a European Classification (Euroclass) of A1 or A2-s1,d0. 

As we have discussed in our #FireSafetyMatters series, however, there are some notable drawbacks with how the Euroclass system assesses products within this linear route to compliance. The testing used within Euroclass is mostly conducted on small samples of individual products in isolation. The results may therefore not be wholly representative of the fire performance of complete system build-ups. Indeed, systems which meet these requirements have been shown to fail large-scale testing.  

In our opinion, it is best to use configurations which are backed by large-scale testing data. 

Non-relevant buildings

As their name suggests, this category captures all other buildings with storeys 18 meters, or more, above ground level. 

Under the guidance in ADB-2019, products used on these buildings can again be assessed under the Euroclass System where they are required to achieve a classification of at least A2-s3,d2. Cavity wall constructions, including those using Kingspan Kooltherm K106 and K108 do not need to meet this requirement. Their use is permitted on “non-relevant buildings”, providing the cavity is between two leaves of brick/concrete each at least 75 mm thick and the cavity is closed at openings and the top of the wall (see Diagram 9.2 in Section 9 of ADB-2019 Volume 2 for further guidance).

Alternatively, ADB-2019 allows external wall systems for “non-relevant buildings” to be assessed using the large-scale test BS 8414 under the performance criteria given within BR 135.

Performance-based testing – BS 8414

In this test, the complete façade system being assessed is installed on a two-winged min 8 metre tall rig. A large wooden crib is placed at the base of the wall, lit and allowed to burn for 30 minutes exposing the façade to flames (producing a peak heat release of around 4.5 MW). The crib is then extinguished, and the assembly assessed for a further 30 minutes.

This large-scale approach provides a rigorous evaluation of how all of the elements within a façade can be expected to perform when exposed to a fire as a system.

Complete external façade systems which have been tested using BS 8414 and meet the criteria within BR 135 are suitable for use on “non-relevant buildings”. An up-to-date list of all façade systems which have been tested under BS 8414 and meet the BR 135 criteria is available on our latest test results page.

Additional Routes

Two further routes to compliance are available for “non-relevant buildings”:

Assessment-based Route — A report is prepared in lieu of a test where sufficient testing evidence is available from UKAS accredited testing bodies. This should be prepared by organisations with the necessary expertise (for example, organisations listed as `notified bodies' in accordance with the European Construction or laboratories accredited by the United Kingdom Accreditation Service), to the relevant standard for extended application for the test in question.

Fire Safety Engineering Route — This requires a detailed assessment of all aspects of a building from a fire safety engineer. In addition to considering the performance of the construction in a fire event, it also considers human behavioural aspects, fire prevention and active and passive fire protection measures.

Where can Kingspan’s insulation products be used on walls above 18 m?

Kingspan’s insulation solutions do not achieve a European Classification of at least A2-s3,d2 and therefore are not suitable for the linear route to compliance (via Euroclass assessment) for “relevant” and “non-relevant buildings” or the fire safety engineering route for “relevant buildings”.

Kingspan Kooltherm K106 and K108 Cavity Board are acceptable for use within masonry cavity wall constructions on “non-relevant buildings” above 18 metres providing the construction Diagram 9.2 in Section 9 of ADB-2019 Volume 2. This requires two leaves of concrete and brick which are at least 75 mm thick with a closed cavity around the opening and at the top of the wall (unless the cavity is totally filled with insulation). 

Kingspan Kooltherm K5 External Wall Board, Kingspan Kooltherm K15 Rainscreen Board and the Kingspan TEK Cladding Panel have been tested in specific configurations using BS 8414 under the performance criteria within BR 135. These specific configurations, which can be viewed on our BS 8414 test results page, are suitable for use under the performance-based route to compliance for “non-relevant buildings” above 18 m.

The products below can all be used as part of the assessment-based and fire safety engineering routes to compliance for non-relevant buildings above 18 m:
•    Kingspan Kooltherm K106 Cavity Board
•    Kingspan Kooltherm K108 Cavity Board;
•    Kingspan Kooltherm K5 External Wall Board;
•    Kingspan Kooltherm K15 Rainscreen Board; and 
•    Kingspan TEK Cladding Panel

For more information about the new requirements within ADB 2019, download our technical bulletin and keep an eye on our #FireSafetyMatters page
 

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