How building with wood can be safe and sustainable

Ian King, COO, Zeroignition, discusses the benefits of timber construction – both environmental and safety

Looking ahead to what awaits construction in the UK in 2022, innovation, sustainability and safety are recurring themes we would all do well to embrace.

I think 2022 will put more emphasis on timber construction, not least because it will tick each of the topical boxes above. We all know, or are increasingly aware of, the advantages of timber frame construction over “traditional” materials in terms of environmental impact, as well as reduced waste on site. Not only does this allow for faster, lower carbon builds, but it also increases the amount of offsite construction.

One of the biggest advantages of modular construction is the enforced quality control. In an offsite “factory” type environment, more extensive safety checks can be performed and monitored. This will help ensure that each component meets industry standards and performance levels, including fire. In turn, this can help improve the integrity of the manufacturing quality of the finished product.

Woodburns – this creates a psychological “problem”

However, a barrier remains when it comes to using wood in construction. How can we expect to build safe homes, following disasters like Grenfell, using a material that we know how to burn? Surely, should we go for stone, concrete and the old brick and mortar approach? This is what the UK construction industry is used to. So, this fits the narrative of “let’s not change what we do – we already work with safe materials”, and begs the question: why would anyone switch to materials that are apparently flammable?

But what about fire hazards?

If we think of solid timber framing – as this International Timber article suggests – timber actually outperforms concrete or steel at high temperatures. The chemical and physical structure of concrete changes completely and steel turns into “spaghetti”. The rate of charring of the wood, which slows the progress of the fire, is predictable, which means that it would be incorrect to assume that wood does burn and that steel and concrete do not.

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

With the correct legislation being followed, good design, and a healthy dose of common sense, there is no reason that wood cannot be as safe in a fire as these other materials. Wood even has the potential to be safer than other construction methods with an optimal choice of fire treatment, profiles and species.

Safe and durable

Safety can be further improved if you use wood that has been treated with a specialized 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 does each one perform in terms of fire safety and the environment?

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

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

  1. Nitrogen flame retardants: Commonly used for melamine-based products, the advantage of nitrogen flame retardants is the absence of dioxins and halogen acids as well as low smoke development.

Publish: For adequate flame retardant performance, large amounts of this flame retardant must be added. This can potentially alter the structural integrity of some materials.

  1. Intumescent coatings: when fire strikes, these coatings expand considerably to create a fire resistant and insulating layer on the surface of the material. This can prevent or slow down structural damage by heat deformation.

Publish: These coatings can only be used for specific applications. They are flame retardant but do not offer thermal protection at room temperature or insulating properties.

  1. Inorganic flame retardants: It is found in paints, adhesives, wires and cables, and fabric coverings.

Publish: In this case, many inorganic compounds are used. These have the potential to cause environmental and health problems as they have to be combined with other types of flame retardants such as halogenated flame retardants.

  1. Phosphorus flame retardants: science has proven that this is the most environmentally friendly grade and forms the basis of Zeroignition’s flame retardant additive product portfolio.

When exposed to fire, these flame retardants promote charcoal formation and generate less smoke compared to other categories of flame retardants.

Ongoing innovation continues to propel the use of fire retardant treated lumber in construction. Add to that a strict systematic approach to fire safety from the start of construction and you have the best of both worlds.

This should not be seen as a trade-off between environmental benefits and reduced safety – both are very achievable.

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