Approved Document F Volume 1 vs Volume 2 – Which One Applies to Me?

Ventilation and indoor air quality (IAQ) have become some of the most important and tightly regulated factors impacting the health and comfort of building occupants in the UK. Whether you’re involved in new builds or retrofit projects, understanding the ventilation requirements UK regulations impose is crucial, especially when referencing Approved Document F (ADF) and the Scottish Building Standards.

In this post, I’ll unpack the differences between Approved Document F Volume 1 and Volume 2 — which one applies to your project, how ventilation requirements are structured, and what to watch out for during retrofit schemes, especially in older properties like Edinburgh’s tenements.

What is Approved Document F?

Approved Document F is a part of the UK Government’s suite of building regulations specifically addressing ventilation requirements UK. It focuses on ensuring adequate provision of fresh air across residential and non-residential buildings to safeguard occupant health by controlling moisture, pollutants, and indoor contaminants.

It is published by the UK Government and can be viewed on the gov.uk site, detailing prescribed ventilation rates and design principles.

Image credit: Magnific

Volume 1 vs Volume 2 – What’s the Difference?

Approved Document F is split into two volumes which target different types of buildings:

Volume 1: Applies to dwelling houses — including single-family homes, flats, maisonettes, and generally residential settings where people sleep and spend much of their time. Volume 2: Covers buildings other than dwellings, such as offices, retail, schools, hospitals, and larger non-residential premises.

For most domestic retrofit or new build projects involving homes, Volume 1 is the go-to document for ventilation requirements UK standards.

Volume 1 Highlights

Volume 1 sets minimum airflow rates for rooms to ensure pollutant dilution and moisture control. It provides guidance on different ventilation methods including: ...you get the idea.

Background ventilation (trickle vents or equivalent mechanical supply) Extract ventilation (in kitchens, bathrooms, utility rooms) Whole house mechanical ventilation systems where applicable

Volume 2 Highlights

Volume 2 is broader, covering a wide range of building types, and includes requirements for:

Specific local exhaust rates tailored per building function Whole-building ventilation strategies Considerations for pollutant sources specific to non-domestic uses

Scottish Building Standards and Approved Document F – How Do They Compare?

Since many projects in Edinburgh and elsewhere in Scotland adhere to the Scottish Building Regulations (administered by the Scottish Government’s Technical Handbooks), it’s worth noting the similarities and differences compared to UK Government Approved Document F.

In principle, the ventilation requirements across these regimes align heavily; both aim to maintain healthy indoor air quality by controlling moisture how to design for daylight and reducing pollutants. Where they differ tends to be numerical values of ventilation rates or specific contexts, reflecting regional climate, construction traditions, and regulatory structure.

If you’re working on a project in Scotland, the Scottish technical handbook is your reference point. But the ventilation principles underpinning both documents are congruent enough that the understanding of one informs the other well, especially related to:

Moisture and condensation control Airtightness considerations Use of ventilation strategies

Airtightness vs Accidental Ventilation in Retrofits

One of my persistent concerns in retrofit projects — especially for traditional tenements and pre-war properties — is the disconnect between improving airtightness and ensuring suitable ventilation provision. Increasing airtightness is critical for thermal performance, but it can drastically reduce accidental ventilation (air leakage through cracks, gaps, or poorly detailed openings).

I'll be honest with you: relying on accidental ventilation is a risky strategy. It’s uncontrolled, variable depending on weather and occupant behaviour, and often inadequate to address moisture and pollutant loads. Instead, retrofits need designed ventilation schemes that:

Comply with Volume 1 ventilation rates Consider the direction main rooms face (which impacts solar gains and ventilation needs — something I always ask about on site) Implement either enhanced natural ventilation, passive stack ventilators, or mechanical extraction where necessary

Moisture, Condensation, and Mould – Symptoms of Ventilation Gaps

During post-occupancy evaluations and tenant visits, I often find that mould and condensation issues in homes correlate strongly with gaps in ventilation strategy. Moisture generated by cooking, bathing, drying clothes indoors, and occupant respiration must be actively managed.

Without adequate ventilation, moisture accumulates, resulting in condensation on cold surfaces, which in turn fosters mould condensation in flat causes growth. This is not just an aesthetic or maintenance headache — it directly impacts occupant health.

Cheap indoor air monitors can help detect elevated humidity levels early, but monitoring carbon dioxide (CO2) indoors provides a reliable proxy for ventilation adequacy. High CO2 levels (>1000 ppm) often indicate insufficient fresh air exchange.

As someone who always keeps a pocket CO2 monitor in my site bag, I recommend using these devices both during commissioning and post-occupancy to ensure continuous healthy air quality.

Useful Tools and Resources

To help you manage ventilation effectively, here are some helpful tools and educational resources I rely on and recommend:

Cheap indoor air monitors: Handy for measuring CO2 and humidity levels on-site or at home to verify ventilation effectiveness. Carbon dioxide (CO2) as proxy: Use CO2 monitoring as a practical metric to gauge if ventilation rates meet the standards prescribed. Magnific: Their installation teams offer quality ventilation upgrades and can advise on compliance with Approved Document F. Releaf’s THC oil education page: While unrelated to ventilation regulations, it is a great example of how indoor air quality interplays with occupant wellbeing regimes; remember, buildings do not “treat” illness, but proper ventilation supports health.

Summary Table – Which Volume Applies and What You Need to Know

Aspect Approved Document F Volume 1 Approved Document F Volume 2 Applicable Building Types Dwelling houses: houses, flats, residential units Non-domestic buildings: offices, schools, shops, hospitals, etc. Ventilation Focus Minimum fresh air requirements for homes; background + extract ventilation Local exhaust and whole-building ventilation for varied non-domestic uses Airtightness Considerations Critical to balance with adequate designed ventilation in retrofits Similar principles apply, but often combined with more complex system design Performance Metrics Airflow rates in l/s per room type; CO2 proxy recommended for assessment Airflow rates specified by building use; detailed strategies for pollutant control Regulatory Reference UK Government: gov.uk UK Government: gov.uk

Final Thoughts – Don’t Compromise Ventilation When You Retrofit

It’s tempting on retrofit projects to focus heavily on insulation and airtightness to reduce heat loss, and sometimes this leads to value engineering that removes ventilation basics. As I’ve seen far too often, ignoring ventilation leads to unresolved mould, condensation, and ultimately poor occupant health (despite claims sometimes made about wellbeing enhancements — a pet peeve of mine is when a project incorrectly implies a building “treats” illness).

By knowing which volume of Approved Document F applies to your project and committing to its requirements, you can ensure you deliver buildings that truly safeguard indoor air quality.

And always remember: measuring indoor conditions—both humidity and CO2—is your best ally in confirming ventilation adequacy. If you’re in Scotland, consult the Technical Handbook, but lean on the principles established in Approved Document F as a strong foundation.

For those interested in sustainable and health-aware retrofit, companies like Magnific can provide practical help with ventilation upgrades, and educational resources from organisations like Releaf underline the intersection of indoor environment quality and occupant wellbeing.