Approved Document F, Volume 1, the UK building regulations that govern ventilation in residential homes, has just been reissued for 2026. For most people, it's a rather dry read, so here's the short version: in 2027, new homes will need more mechanical ventilation, which means a lot more ductwork. If you're specifying, fitting, or buying ducting for residential properties, this is worth five minutes of your time.
See our standards and legislation page for the wider picture.
Approved Document F is the government guidance that tells builders how to ventilate a home properly — enough fresh air in, enough stale air and moisture out. It sits alongside Approved Document L (energy efficiency) as part of the Future Homes and Buildings Standards. The 2026 edition is the biggest shake-up it's had in years.
Three changes stand out.
Ventilation rates for the whole house have gone up. It's no longer just about a decent extractor fan in the bathroom and kitchen — the entire dwelling needs to hit a higher minimum air change target.
There are now three system types instead of four. The old four-category system is gone. The 2026 edition works with:
Natural ventilation: trickle vents and extract fans, only suitable for less airtight homes
Continuous mechanical extract ventilation (MEV): a system that quietly extracts stale air around the clock
Mechanical ventilation with heat recovery (MVHR): extracts stale air and supplies fresh air, recovering the heat from the outgoing air on the way
The big shift: MEV and MVHR are now written into the guidance as suitable for every dwelling, not just the very airtight ones. As homes keep getting built tighter and better insulated, natural ventilation on its own is falling out of favour. Continuous mechanical ventilation is fast becoming the default, not the exception.
Flexible ducting cannot be used in runs longer than 200mm. That means that semi-rigid ducting, like Elephant Duct, is now the easiest way to connect medium-length to long stretches of ductwork for MVHR, MEV, FCU, etc. In the previous version (Part F 2021) , flexi-duct could be up to 1.5m long, so this 2026 update essentially crushes the number of useful applications for flexible ducts.
Yes, MVHR needs two separate duct runs instead of one. An MVHR system has to bring filtered fresh air in as well as extract stale air out, so a home needs a supply duct run and an extract duct run, both threaded through the same joists, voids, and stud walls. Compare that to MEV or a simple extract fan, which only need one run for extraction. For anyone fitting ductwork, that's a real jump in the volume of duct going into every new-build loft and wall cavity.
That's exactly where semi-rigid ducting earns its keep. Two duct runs through the same tight void space means more bends, more awkward junctions, and less room for anything that sags, kinks, or needs boxing in on-site. Our Asian Elephant (4mm), African Elephant (8mm), and Woolly Mammoth (25mm) products are all built to hold their shape through tight bends without the on-site lagging or careful coordination that rigid ductwork demands. That's useful when you're fitting double the duct in the same roof space.
All three Elephant Duct ranges are Class B-s2, d0 rated to EN 13501-1:2019, meaning average smoke output and no flaming droplets in a fire. This rating is much higher than your typical cheap flexi-duct brand currently getting shoved into residential loft spaces, which can soften and melt very quickly in the event of a fire. Our fire-resistant ducting is built to prevent fire spread as effectively as possible.
With more ductwork now running through more of the building fabric on a typical new-build, that fire performance matters on more linear metres of duct than it used to.
Proving the system works is now taken more seriously too. MVHR systems need to be properly commissioned, with a certificate to show for it. MEV systems need to be checked against their design airflow rates, not just switched on and left. And homeowners are meant to get a plain-English explanation of how their ventilation works when they move in — a direct response to the well-known problem of people switching systems off or blocking vents because nobody told them what they were for.
None of that changes what goes in the wall. But it does mean a kinked, undersized, or leaky duct run is far more likely to get caught before sign-off than it was before.
The 2026 edition of Approved Document F takes effect on 24 March 2027 for standard building work, and 24 September 2027 for higher-risk buildings, with transitional arrangements for projects already under way. That sounds a long way off, but ventilation design for new builds happening right now should already be working towards these requirements — specification and procurement run well ahead of the compliance date. Always check the current published edition of Approved Document F on gov.uk before treating any figure here as final, as guidance gets amended.
Specifying ductwork for a project moving to MVHR or MEV under the updated Part F? We can talk you through which Elephant Duct range fits the run. Get in touch or browse the full product range.