A suspected drug dealing den on the Meriden estate will remain shut down due to a court order.
The original order was granted in October after the force received numerous complaints from neighbours about nuisance behaviour and suspected drug dealing.
Nikki Simons, Hertfordshire Constabulary Anti-Social Behaviour Officer, said: "We are extremely pleased with the outcome of this hearing. The property has been subject of anti-social behaviour for a long period of time. I’m pleased to say that we have had no reports of anti-social behaviour at the address since the order was granted back in October and the residents’ quality of life has improved tremendously."
Under the original terms, the occupant, Roger Lewis, is ordered not to enter the property for three months. On Thursday magistrates at St Albans Magistrates Court extended that order until April.
Police said no one is allowed into the flat and any attempts to gain access will result in a breach of the closure order and arrest.
Following the decision, Dave Wheatley, Watford’s chief inspector, said: "Clearly the closure has made a big difference to the lives of residents living in Pinetree House and this has been achieved through the hard work and determination of anti-social behaviour officers, from both the constabulary and Watford Community Housing Trust."
Watford Community Housing Trust ASB Officer Denise Cole added: "This crack house closure has shown that working together in partnership, alongside the residents of the block who have suffered ASB for a number of years, we can achieve a positive outcome for all. This sends a clear message to all that we will not put up with this type of behaviour and we will take action against your tenancy."