- Ventilation flues should be led from chimney entry to its exit. Escape holes should be made on the sides of the chimney. Upper escape holes are acceptable, provided that chimney pot is placed above the exit.
- Ventilation flues should be made of uninflammable materials. All inflammable thermal or acoustic isolations of the flues can be used only on the external surface in a way not allowing fire to spread.
- Cross-sectional area of flues for gravity ventilation should be at least 0,016 m2, and the smaller dimension of the cross-section – at least 0,1 m.
- Distance between bare ventilation flues and inflammable surfaces should be at least 0,5 m.
- Doors used in ventilation flues and channels should be made of uninflammable materials.
- In kitchens and kitchen cavities exhaust ventilation flues can be made of flash-resistant materials.
- No other installations can be led in ventilation flues.
