Last edited 17 May 2024

Specifying rendered external wall insulation for fire safety

EWI Render Falling 1000.jpg


[edit] Fire safety: What specifiers need to look for when reviewing render and EWI performance information

The issue of fire safety remains of paramount importance. The Building Safety Act is arguably causing the biggest changes the construction industry has seen since the implementation of the Building Regulations in 1984.

As part of this, there has been a large focus on the performance claims of product manufacturers. This was originally highlighted in Dame Judith Hackitt’s 2018 Independent Review of Building Regulations and Fire Safety, when she pointed out that the system for testing and ‘certifyingproducts for use in construction was “disjointed, confused, unhelpful, and lacks any sort of transparency.”

Since then, the Construction Product Association (CPA) has initiated the Code for Construction Product Information (CCPI), which aims to provide assurance that users of product information have the necessary facts when making decisions about specifying or installing their products.

The government’s Independent Review of the Construction Products Testing Regime: Testing for a Safer Future, further reinforced the need for accurate product information, concluding that manufacturers have a responsibility to develop products that do the job expected of them and to market them honestly, making no false or misleading claims.

With so much information out there, what should specifiers and designers consider when reviewing the fire safety claims being made by any product manufacturer today?

When it comes to renders and related external wall insulation (EWI) systems, specifiers should be encouraged to interrogate the evidence provided and review the following information

[edit] Conduct wind load calculations

The design of any EWI or cladding system is required to resist predicted wind load pressure both in relation to the location and height of the building, and considering its orientation, surroundings and building design/shape along with the weight of the system. The specified fixings and fixing systems need to be designed to deal with these predicted loads in mind and installed accordingly.

Any installed cladding system must be able to resist the effects of predicted wind pressure.

[edit] Ensure a pull out test is completed

Normally performed to establish the load-bearing capacity and strength of fixings specified for a wall, slab or soffit, pull out tests are vital to ensure that anything fixed to the building will stay safely secured under duress. In the case of EWI, the correct length, type and material of fixing are all relevant to ensuring the insulation is reliably fastened to the substrate.

The assessment involves attaching a suitable test rig to the screw, anchor or fixing. This is then put under tension to the designed stress load level to determine how strong and secure the fixing is, enabling potential early diagnosis of underlying problems. It is also advisable to undertake site pull out tests on the product being used while installation is taking place, as data found in manufacturers’ literature may vary and there can be a difference in product batches of the same product.

[edit] Don’t just look for an A1 or A2 reaction to fire classification

Look much deeper into claims around fire safety performance than you may have done in the past. It’s not enough just to look for the required classification; it’s the information that sits behind this grading that matters most, along with a lot of other complementary data.

The Euroclass test relates to reaction to fire. Do you have all the test data and, if so, to what standard was that test carried out? Was the testing done by a UKAS-accredited test centre? Have you seen the actual test data or just gone from claims in the marketing literature?

There is also the possibility that product/system may also need to meet a fire resistance requirement in addition to reaction to fire, which takes into account load-bearing capacity, integrity and insulation.

Product decisions should only be made based on the full suite of documentation, including the complete set of individual test reports to fully appreciate if the proposed solution meets all requirements of Building Regulations.

[edit] Consider how colour impacts performance

Historically, manufacturers have only tested lighter colours such as white or cream for reaction to fire – not just because these are the most popular colours, but also because of the amount of organic (and therefore less combustible) content, so they are more likely to pass a fire test more easily. This is clearly not in the spirit of the Hackitt recommendations, nor the culture of product safety now required.

An appropriate range of colours should be tested separately with the support of a UKAS-accredited testing facility. Weber is one such manufacturer to have this assessment covering its full colour range – including reds, which are most likely to contain the highest level of organic content. Dark colours such as greys and yellows can also throw up interesting test results that need careful checking.

[edit] Ensure that all documentation matches up

The Euroclass certification for a product should align with the individual test reports. The test reports should align with the Declaration of Performance (DoP).

Another thing that needs checking is the date of the test data to ensure it is still valid and hasn’t expired.

Any change to a product’s formulation, no matter how small, means that previous test data may be invalid, and the product should undertake an agreed level of testing working with a notified body.

The biggest hurdle is just becoming better educated and familiar with testing regimes and what different test reports are saying. Once you are familiar with what you’re looking at, it’s not difficult to identify anomalies.

As part of the new building safety regime, all dutyholders - the client, the principal designer and the principal contractor - are required to ensure that there are arrangements and systems in place to plan, manage and monitor design and building work to ensure compliance with Building Regulations.

Architects and specifiers will likely be the principal designer or designer dutyholder. The principal designer is the designer who is in control of the design work and is responsible for ensuring that the design phase complies with Building Regs and building safety. This includes checking the design elements, such as EWI systems, and the associated documentation.

Keep asking questions and complete the necessary research to ensure the product/systems will meet the required performance claims. Any reputable product manufacturer will be happy to share all their test data openly and honestly.

For further advice on the specification of Weber EWI and render systems, go to:

This article was issued via Press Release as 'Fire safety: What specifiers need to look for when reviewing render and EWI performance information' dated May 16, 2024.

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