CWFT Timber Cladding Rules Have Changed.
Here's What Specifiers Need to Know Now.
The rules around BS/EN14915 fire classification for timber cladding have changed, and the shift is significant. The long-standing assumption that timber products could rely on CWFT (Classified Without Further Testing) status is no longer safe ground. Recent regulatory updates mean only untreated solid timber qualifies for CWFT. Anything treated, modified, coated or enhanced now falls outside the automatic Euro class D-s2,d0 bracket and requires full documentation for the claimed fire class according to BS/EN13501-1:2018.
What Has Changed?
Under the EU Commission Delegated Regulation C(2023) 7486, the CWFT framework has narrowed. It now dictates precisely how BS/EN14915 must be applied to fire reaction characteristics, and it closes the loophole that previously allowed treated or modified wood to slide through without being individually tested.
What No Longer Qualifies?
Starting August 2024, the CWFT table applies only to untreated wood with a minimum density of 390 kg/m3. Treated, modified, thermally altered, impregnated and coated products are no longer automatically classified. These now require EN 13501-1 fire testing by an accredited third party.
Under European fire safety regulations, untreated solid timber can still quality for CWFT when it meets strict criteria for density, thickness, installation method and substrate performance. But the industry line is now unambiguous: This pathway applies only to untreated timber. Any product that undergoes a modification or treatment process, including Thermo wood, is no longer eligible for CWFT and must be individually tested to verify its reaction-to-fire performance. With CWFT reserved for predictable, stable materials that meet specific parameters, HALT’s position is clear: if it’s treated, it’s out. Thermo wood is treated. And the days of assuming it qualifies under Euroclass D-s2,d0 without testing are over.
Why This Matters
• No more assumptions. “Wood is D” is no longer a valid stance for modified products
• Surface coatings count. Even aesthetic or durability coatings reclassify timber as “modified”, removing CWFT eligibility.
• Minimum performance still mandatory. All wood products, treated or untreated, must meet D-s2,d0 (or D-s2,d2 in some cases) through proven testing.
• Legally binding. This update is now EU law under the Construction Products Regulation, and applies across all member states and Northern Ireland. It also includes most of countries and territories that are have accepted the CPR in their national legislation, e.g. Norway and Switzerland.
The Bottom Line for Specifiers
If your timber cladding isn’t untreated, it cannot be assumed to meet minimum Euro class D without proper and valid documentation. And if it doesn’t have a verified Euroclass classification, it doesn’t meet the bar. This update isn’t a small tweak, it’s a reset. The industry must now treat fire testing as essential, not optional.
And there’s another critical point that can’t be ignored: there is no blanket classification for all timber species. No shortcuts, and no “one-size-fits-all” approach to testing. Each species behaves differently under exposure to heat and flame, meaning each one must be individually tested to determine its reaction-to-fire performance. If a product is being sold, specified or installed, its fire performance needs real data behind it. That’s the only way to guarantee accuracy, safety and integrity across the supply chain.
Work With HALT to Stay Compliant, Credible and Competitive
HALT specialises in helping timber suppliers navigate the new regulatory landscape with zero ambiguity. We ensure every product is tested, classified, documented and ready for specification under the tightened CWFT rules.
Working with HALT means:
• Full compliance, no guesswork. We guide you through EN 13501-1 requirements, so every product meets the bar.
• Independent, accredited fire testing coordination. Avoid delays and costly missteps, HALT manages the process end-to-end
• Clear, specifier-ready documentation. The new rules demand transparency, especially now that modified timbers no longer qualify for automatic Euro class D-s2,d0 classification.
• Confidence in every project. Specifiers are under increasing scrutiny. HALT helps you become the supplier they trust.
The industry is moving. Don't get left behind.
Work with HALT today to ensure every timber product you supply is compliant, test-proven and future-proof.
What Has Changed?
Under the EU Commission Delegated Regulation C(2023) 7486, the CWFT framework has narrowed. It now dictates precisely how BS/EN14915 must be applied to fire reaction characteristics, and it closes the loophole that previously allowed treated or modified wood to slide through without being individually tested.
What No Longer Qualifies?
Starting August 2024, the CWFT table applies only to untreated wood with a minimum density of 390 kg/m3. Treated, modified, thermally altered, impregnated and coated products are no longer automatically classified. These now require EN 13501-1 fire testing by an accredited third party.
Under European fire safety regulations, untreated solid timber can still quality for CWFT when it meets strict criteria for density, thickness, installation method and substrate performance. But the industry line is now unambiguous: This pathway applies only to untreated timber. Any product that undergoes a modification or treatment process, including Thermo wood, is no longer eligible for CWFT and must be individually tested to verify its reaction-to-fire performance. With CWFT reserved for predictable, stable materials that meet specific parameters, HALT’s position is clear: if it’s treated, it’s out. Thermo wood is treated. And the days of assuming it qualifies under Euroclass D-s2,d0 without testing are over.
Why This Matters
• No more assumptions. “Wood is D” is no longer a valid stance for modified products
• Surface coatings count. Even aesthetic or durability coatings reclassify timber as “modified”, removing CWFT eligibility.
• Minimum performance still mandatory. All wood products, treated or untreated, must meet D-s2,d0 (or D-s2,d2 in some cases) through proven testing.
• Legally binding. This update is now EU law under the Construction Products Regulation, and applies across all member states and Northern Ireland. It also includes most of countries and territories that are have accepted the CPR in their national legislation, e.g. Norway and Switzerland.
The Bottom Line for Specifiers
If your timber cladding isn’t untreated, it cannot be assumed to meet minimum Euro class D without proper and valid documentation. And if it doesn’t have a verified Euroclass classification, it doesn’t meet the bar. This update isn’t a small tweak, it’s a reset. The industry must now treat fire testing as essential, not optional.
And there’s another critical point that can’t be ignored: there is no blanket classification for all timber species. No shortcuts, and no “one-size-fits-all” approach to testing. Each species behaves differently under exposure to heat and flame, meaning each one must be individually tested to determine its reaction-to-fire performance. If a product is being sold, specified or installed, its fire performance needs real data behind it. That’s the only way to guarantee accuracy, safety and integrity across the supply chain.
Work With HALT to Stay Compliant, Credible and Competitive
HALT specialises in helping timber suppliers navigate the new regulatory landscape with zero ambiguity. We ensure every product is tested, classified, documented and ready for specification under the tightened CWFT rules.
Working with HALT means:
• Full compliance, no guesswork. We guide you through EN 13501-1 requirements, so every product meets the bar.
• Independent, accredited fire testing coordination. Avoid delays and costly missteps, HALT manages the process end-to-end
• Clear, specifier-ready documentation. The new rules demand transparency, especially now that modified timbers no longer qualify for automatic Euro class D-s2,d0 classification.
• Confidence in every project. Specifiers are under increasing scrutiny. HALT helps you become the supplier they trust.
The industry is moving. Don't get left behind.
Work with HALT today to ensure every timber product you supply is compliant, test-proven and future-proof.