Continuous extraction is a proactive measure against mould because it removes moist air before condensation occurs. By maintaining steady airflow, it prevents damp from building up on cold surfaces, reducing the risk of mould growth, structural damage, and health problems in UK homes.
Understanding Continuous Extraction #
Continuous extraction means running fans at a low, steady rate 24/7. Instead of relying on intermittent bursts, the system constantly removes humid air from kitchens, bathrooms, and other moisture-prone spaces. This ensures relative humidity remains stable, preventing condensation on cold surfaces.
Why Mould Forms in Homes #
-
Condensation: Warm air holds more moisture. When it hits a cold wall or window, water droplets form.
-
Poor ventilation: Without steady airflow, moisture lingers, soaking into plaster, paint, and fabric.
-
Favourable conditions: Mould spores thrive in damp, stagnant environments—particularly at humidity above 70%.
In the UK, with its damp climate and increasingly airtight homes, mould risk is higher than many people realise.
How Continuous Extraction Works #
-
Constantly draws out humid air.
-
Low-speed background ventilation prevents spikes in moisture.
-
Boost mode activates when needed (e.g. during showers).
-
Works quietly in the background, unlike noisy intermittent fans.
This steady removal makes it proactive—solving the problem before it begins.
Evidence from UK Standards #
-
Part F of the Building Regulations requires adequate means of ventilation, with continuous systems increasingly seen as best practice.
-
Studies show that relative humidity consistently above 70% encourages mould growth, while keeping it between 40–60% reduces risk.
-
BRE (Building Research Establishment) highlights poor ventilation as a key contributor to damp and mould in housing.
Benefits Beyond Mould Prevention #
-
Healthier indoor air: Removes allergens, volatile organic compounds, and pollutants.
-
Reduced heating bills: Prevents moisture from reducing insulation performance.
-
Protects the building fabric: Avoids plaster damage, timber decay, and corrosion.
-
Peace of mind: Operates quietly and reliably without user intervention.
Continuous vs Intermittent Extraction #
| Feature | Continuous Extraction | Intermittent Extraction |
|---|---|---|
| Operation | 24/7 low rate | Short bursts only |
| Moisture control | Prevents build-up | Reacts after moisture appears |
| Noise | Quieter | Louder when activated |
| Energy use | Low, steady | Higher peaks |
| Mould prevention | Proactive | Reactive |
Continuous systems clearly outperform intermittent ones for long-term protection.
Practical Applications in the UK #
-
New builds: Centralised MVHR systems provide whole-house ventilation with heat recovery.
-
Retrofits/refurbishments: Decentralised single-room units are easier to install without ducting.
-
Extensions: Localised systems ensure new spaces are ventilated to modern standards.
VENTI systems such as ARIA (dMEV) for wet rooms or RESPIRO (MVHR) for whole homes are designed precisely for these needs.
Continuous extraction prevents mould by tackling moisture at source—helping UK homes stay healthier, warmer, and structurally sound.