Fire retardant wood: How it's made

Published Thursday 18th September 2014

Wood's cost-effectiveness, versatility and excellent green credentials have made it a perennially popular product for builders. 

However, the fight against its arch nemesis – fire – is never-ending and the quest to vanquish or at least fend off this fiendish foe has led to some exciting developments in timber technology. 

In this guide, we'll take a look at some of the options available for those looking to protect their wood from fire and why, in some cases, wood can even outperform concrete and steel when it comes to handling heat.

Why does wood catch fire?

We all know that untreated wood can catch fire easily, which has made it a staple source of fuel throughout human history. But how does this process work?

Fire occurs when a material becomes hot enough to reach ignition temperature (around 150 degrees C) in the presence of sufficient oxygen. As wood is a very poor conductor of heat (when compared to metals for instance), the heat will decompose some of its cellulose material, creating smoke.

Once this reaches prime temperature (around 260 degrees C), the molecules themselves will break apart and the constituent atoms will recombine with the oxygen, commencing the burning process.

Wood fires are largely self-sustaining in the presence of sufficient amounts of fuel and oxygen as the chemical reaction generates a great deal of heat in itself. However, the consistency of the wood will also play a role – with thinner pieces burning faster due to greater exposure to oxygen.

The Need for Fire Retardant Wood

As wood is such a vital and commonplace construction fixture, when being used en masse in a building, there's obvious safety advantages to be had from fire-proofing your timber.

Correctly treated wood can slow the spread of flames, allowing more time for personnel to escape in the event of a fire, as well as reducing damage to the structure and giving greater time to extinguish the blaze.

There's also a range of legislation governing the safety aspects of timber usage, as well as specific building regulations on fire protection, which treated timber can help construction companies comply with.

Making wood fire retardant

Bringing wood up to fire retardant specification will typically involve the application of a chemical formula that will protect the timber and is suited to its end use.

While there's a wealth of branded formulas out there, the vast majority work by altering the way the combustible elements of wood work when exposed to high temperatures.

By preventing the build-up of flammable gases and tars generated in untreated wood and converting them into less reactive elements, the combustion process can be impeded – reducing the amount of ignition, hampering the spread of flames and the amount of heat released.

How we do it

We work together with Lonza Wood Protection, which offers our customers a choice of tried and tested treatments to suit a wide range of construction projects.

For timber and sheet material that'll be used in internal or weather-protected situations we utilise DRICON, while NON-COM Exterior is used for wood that'll be exposed to the elements or face severe dampness.

DRICON is a water-based formulation that is resistant to humidity and typically applied in a vacuum pressure impregnation plant before being kiln-dried to ensure the moisture content of the timber returns to the specified level.

NON-COM Exterior is applied in much the same way, but is polymer-based and the treated wood subjected to high-temperature curing to level out the moisture content.

These are designed to meet Euroclass B or C requirements of the Fire Classification of Construction Products and Building Elements and are carried out at Lonza's own treatment plant, which is fully ISO90001 accredited and guarantees the quality of application.

And You?

Hopefully the above has given you an introduction to the basics of fire retardant wood, but if you've got any more questions or simply want to find out the best treatment options for your project, don't hesitate to give us a shout on Twitter or get in touch directly today.

Image used courtesy of Aimee on Pixabay