There are two ways to calculate if rented accommodation is overcrowded (section 234 of the Housing Act 1985), one is by the number of rooms for people to sleep in, this is called the room standard. The other is by the amount of space in the home and the number of people living in it, this is called the space standard.
Statutory overcrowding is when there are too many people living in the property using either of these calculations. The Shelter website gives further information on calculating whether or not the property is overcrowded. A tenant of a property may be committing a summary offence if they cause or permit a property to become overcrowded.