Ventilation Rate Calculator — Extract Rates per Document F

This calculator determines the required ventilation rates for individual rooms based on UK Building Regulations Approved Document F (2021 edition). It covers both intermittent extract rates and whole-dwelling continuous ventilation.

Intermittent extract rates (ADF 2021 Table 1.1)

• Kitchen: 30 l/s with a cooker hood extracting to the outside, 60 l/s otherwise (no hood, or a recirculating hood) — continuous-extract high rate is 13 l/s (Table 1.2)
• Bathroom / shower room: 15 l/s (8 l/s continuous high rate, Table 1.2)
• WC / sanitary accommodation: 6 l/s
• Utility room: 30 l/s (8 l/s continuous high rate, Table 1.2)
• Habitable rooms: No extract required (background ventilation only)

Whole dwelling continuous rates (ADF 2021 Table 1.3)

• 1 bedroom: 19 l/s
• 2 bedrooms: 25 l/s
• 3 bedrooms: 31 l/s
• 4 bedrooms: 37 l/s
• 5+ bedrooms: 43 l/s
• Must also be at least 0.3 l/s per m² of total internal floor area, all floors added together (para 1.24) — use whichever is greater

Background ventilator (trickle vent) equivalent areas (ADF 2021 Table 1.7, natural ventilation)

• Habitable rooms and kitchens: 8000 mm² (10,000 mm² in single-storey dwellings)
• Bathroom: 4000 mm²
• Utility room and WC / sanitary accommodation: no minimum equivalent area
• With continuous mechanical extract instead, para 1.64 requires 4000 mm² per habitable room and no ventilators in wet rooms