Fire-Treated Timber: Ensuring Fire Safety and Building Compliance
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Fire-Treated Timber: Ensuring Fire Safety and Building Compliance

Timber is one of the most sustainable and visually appealing materials in construction, but when it comes to fire safety, understanding how fire-treated timber performs is essential. Whether you’re working on residential cladding or interior finishes in commercial spaces, choosing the right timber treatment can make the difference between full compliance and costly setbacks.


In this guide, we break down how fire-treated timber works, when it's required under UK law, and how to choose the right product for your project.


Fire-Treated Timber

Understanding Fire Ratings and UK Regulations


In the UK, fire resistance is rated by how long a building component can withstand fire, typically 30, 60, or 90 minutes.


These ratings consider:

  • Load-bearing capacity

  • Integrity (resistance to flames)

  • Insulation (resistance to heat transfer)


Fire performance is defined under BS EN 13501-2, with tests based on BS 476-20 to 476-24 or equivalent European standards.


Key applications include:

  • Internal walls/floors (often require 60-minute fire resistance)

  • External cladding on buildings over 11m (must pass BS 8414)


❗Why It Matters: Failing to use fire-treated timber where required can result in non-compliance, failed inspections, or serious safety risks.


What Is Fire-Treated Timber?


Fire-treated timber (FTT) undergoes chemical treatments to slow down combustion, reduce smoke, and improve performance under heat. This allows it to be used safely in locations where untreated timber would otherwise be unsuitable.


✅ Key Benefits of Fire-Treated Timber:


  • Reduces flame spread and ignition risk

  • Forms a protective char layer

  • Lowers smoke toxicity and increases evacuation time


Note: ThermoWood® has some natural fire resistance due to its modified structure, but additional treatment may still be required depending on building use and regulation.


When Is Fire-Treated Timber Required?


Use of fire-treated timber is often mandatory based on:


  • Building height

  • Building use (residential, commercial, healthcare)

  • Location of use (interior, exterior, escape routes)


📋 Regulations to Know:


  • Approved Document B: Main fire safety guidance for England and Wales.

  • Requirement B3: Internal fire spread resistance.

  • Requirement B4: External fire spread — applies especially to cladding.

  • The Building (Amendment) Regulations 2018: Prohibits combustible materials in external walls over 11m in height (previously 18m).


How to Specify the Right Fire-Treated Timber


Choosing the right fire-treated timber means more than selecting a treated product — it means verifying performance, certification, and installation standards.


🧾 What to Look For:


  • Performance Rating: Aim for Euroclass B-s1,d0 (or better), compliant with BS EN 13501-1.

  • Third-Party Certification: Always check for certification by BM TRADA, Warringtonfire, or BRE Global.

  • Correct Installation: Improper handling (e.g. cutting or drilling) can void fire ratings.


🔎 Pro tip: Consult a building control officer or fire engineer when specifying fire-rated timber for high-risk applications.


Why Fire-Treated Timber Ensures Safety and Compliance


Using certified fire-treated timber provides:


  • ✅ Occupant Protection: Slows fire progression and allows more time for evacuation.

  • ✅ Regulatory Compliance: Meets UK building regulations and avoids legal pitfalls.

  • ✅ Reduced Liability: Prevents costly project delays or retrofits due to non-compliance.


Whether you're designing a high-rise residential building or a timber-framed commercial unit, fire-treated timber plays a vital role in keeping people safe and buildings compliant.




Build Beautiful, Build Safe with Fire-Treated Timber


Timber doesn’t have to be a fire risk — with the right treatment and planning, it becomes a fully compliant, beautiful, and sustainable solution. At QTD Ltd, we supply certified fire-treated timber suitable for cladding, decking, and internal applications, all fully tested to meet the UK’s strictest standards.


Need Help Choosing the Right Fire-Treated Timber?


Get in touch with our team for expert guidance on specification, certification, and suitability for your project.

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