The rental sector is still being caught out by unauthorised sub-letting by tenants, which can create financial headaches for those working within this sector.

The Association of Independent Inventory Clerks (AIIC) has warned that unauthorised sub-letting is a significant problem in the United Kingdom, with damage to properties running into thousands of pounds for the property owners. If done without permission, it may be against the terms of any mortgage on the property and may invalidate the insurance.

The AIIC warning comes after the National Landlords Association (NLA) said that almost half of tenants who are sub-letting property do not have the landlord’s or property manager’s authority to do so. Approximately one-third of tenants have asked about sub-letting the property with only one-fifth of them being given the go-ahead. So although sub-letting is not necessarily rife, it is often carried out without permission.

AIIC chairperson Pat Barber spoke of some of the horror stories that she has encountered in the private rented sector. She said she knew of one case where a three-bedroom furnished flat had been let to a restaurant. It emerged that 27 people were living there, all of whom worked shifts in the restaurant trade.

The Government is trying to crack down on unauthorised sub-letting by proposing minimum sizes of rooms. It is hoped that this proposal will reduce unauthorised sub-letting which can be an extremely expensive proposition for owners because of the amount of damage caused. It can also lead to overcrowded, cramped and even dangerous living conditions.

In the meantime, landlords, property management companies and inventory clerks can also keep an eye out for signs that a property is being sub-let without permission, advises Ms Barber.

There may be reports of numerous people coming and going or excessive signs of wear and tear where there are a large number of occupants. The bills may also be higher because 20 people are using the hot water and cooker, for example, instead of three or four.

If the tenant has broken his or her agreement through sub-letting, you can take action to evict them.

If a thorough inventory was carried out during check-in, there is also the chance of recuperating some of the costs incurred through any damage to the property, the owner’s belongings or as a result of excess wear and tear.

As the tenant would have signed the inventory stating the condition of the property and the items therein, it would be difficult for them to make a case as to why they are not responsible for any subsequent damage.