Upvote:1
It is not a requirement, but is among the options, according to the UKVI* guide to supporting documents
Accommodation details
You may wish to submit any of the following documents to provide us with evidence of your accommodation. We advise that you do not make any payments for accommodation, travel and so on until you have received your visa.
Details of the accommodation that you and your sponsor intend to live in and permission for you to stay there along with evidence of any other occupants
This could include:
- Land Registry documents
- mortgage statements
- rent book or tenancy agreement
- council tax statements
- property inspection report
- utilities bills
- accommodation details with a supporting letter from the occupant/ landlord confirming that you are able to stay there
The Housing Act 1985 Part II covers provision of housing accommodation. It gives overcrowding rules and defines what exactly is a bedroom and how many people can occupy it. The overcrowding analysis can be done by a licensed surveyor. In most instances, ECO's take the applicant's word for it.
And while the question is not applicable, this response by @GayotFow has quite a bit of valuable feedback that can help guide you..
*While the linked pdf bears UK Border Agency logo, now UK Visa & Immigration, the content originally published in 2013 has been maintained and updated, most recently in October 2017.