How building with timber can be safe and sustainable?

Ian King, COO, Zeroignition, discusses the benefits of building with timber – both in terms of the environment and also safety

Looking ahead to what’s in store for UK construction in 2022, innovation, sustainability and safety are recurring themes we’d all do well to embrace.

I believe 2022 will bring greater focus on building with wood, not least because doing so will tick each of the topical boxes above. We all know, or are becoming increasingly aware, of the benefits of building with timber frame construction over ‘traditional’ materials when it comes to the environmental impact, as well as reduced waste on site. Not only does it allow faster and lower carbon builds but it also increases the amount of off-site construction.

One of the greatest benefits of modular construction is the enforced quality control. Within an off-site ‘factory’ type environment, greater safety checks can be made and monitored. This will help ensure each component meets industry standards and performance levels, including fire. In turn, this can help improve the integrity of the build quality in the finished product.

Timber burns – this creates a psychological ‘problem’

However, a barrier still remains when it comes to using timber in construction. How can we hope to build safe homes, following disasters like Grenfell, using a material that we know burns? Surely, we should be heading towards stone, concrete and the old bricks and mortar approach? That’s what the construction industry in the UK is accustomed to. So, it fits with the narrative of ‘let’s not change what we do – we already work with safe materials’, and begs the question: why would anyone swap to materials that are seemingly flammable?

But what of the fire risks?

If we think about mass timber frame – as this article from International Timber suggests – wood actually surpasses the performance of concrete or steel at high temperatures. The chemical and physical structure of concrete totally changes and Steel turns to ‘spaghetti’. The rate of char in wood, which slows the progression of the fire, is predictable, meaning it would be incorrect to assume that wood burns and steel and concrete do not.

Now’s the time to rethink our perceptions of wood. It’s an environmental saviour that’s quick to construct and structurally sound. Regulating temperature inside, it reduces waste overall and it provides the fire protection required.

With the correct legislation adhered to, good design, and a hefty helping of common sense, there is no why reason timber cannot be as safe in a fire as these other materials. Wood even has the potential to be safer than other methods of construction with the optimum choice of fire treatment, profiles and species.

Safe and sustainable

Safety can be further enhanced if you use timber that has been treated with a specialist flame retardant, which will provide the material with an invisible shield to help protect against fire.

There are five categories of Flame Retardants, so how well does each perform in terms of fire safety, and ecologically?

1. Halogenated flame retardants: frequently used in the electronics, construction products, textiles and coatings industries.

Issue: This category should be avoided, as the release of chemicals in a fire can be very toxic and detrimental to people and the environment.

2. Nitrogen Flame Retardants: Commonly used for Melamine-based products, the advantage of Nitrogen flame retardants is the absence of dioxin and halogen acids as well as the low evolution of smoke.

Issue: For adequate fire retardant performance high quantities of this flame retardant needs to be added. This has the potential to alter the structural integrity of certain materials.

3. Intumescent Coatings: when fire hits, these coatings expand significantly to create a fire-resistant and insulating layer on the material surface. This can prevent or slow structural damage by deformation from the heat.

Issue: These coatings can only be used for specific applications. They provide fire retardancy but offer no room-temperature thermal protection or insulating properties.

4. Inorganic Flame Retardants: This is found in paints, adhesives, wires and cables, and fabric coatings.

Issue: In this case numerous inorganic compounds are used. These have the potential to cause environmental and health issues as they need to be combined with other types of flame retardants such as Halogenated fire retardants.

5. Phosphorus Flame Retardants: science has proved this is the most environmentally friendly category and forms the basis of Zeroignition’s product portfolio of fire retardant additives.

When exposed to fire these flame retardants promote a char formation, and generate less smoke compared to other fire retardant categories.

Ongoing innovation is continuing to propel the use of fire-retardant treated timber in construction. Couple this with a strict systematic approach to fire safety from the start of a build and it will deliver the best of both worlds.

This shouldn’t be viewed as a case of setting off environmental benefits against reduced safety – both are fully achievable.