The report - Crowded houses - calls for a re-balancing of policy priorities to help more people out of overcrowded conditions, and cut the health and social costs linked to one of the most hidden elements of London's housing crisis.
Led by Andrew Boff AM, on behalf of the Planning and Housing Committee, the investigation tested the hypothesis that building more large homes is a better way to tackle overcrowded social housing - which affects more than 100,000 households in London - and makes a series of recommendations.
Instead of focusing on the number of houses built - an approach which tends to encourage smaller units - the Mayor should base his headline target on the number of new bedrooms provided and measure his success on the number of people taken out of housing need.
Crowded houses illustrates how building one new larger home can result in around 36 people taken out of housing need, while one new smaller home solves the housing problems of only two or three Londoners.
Grant rates need to change to make building larger homes worthwhile. The current flat rates of grant offer little incentive to build larger homes and the report urges the Mayor to lobby for changes to HCA grant rates so they are based on per person housed, rather than a per unit basis.
Boroughs should also give people applying for social housing more "points" for overcrowding, and give under-occupiers greater priority to encourage downsizing. At the moment around 64,000 homes in the social rented sector are under-occupied, which contributes to overcrowding elsewhere in the system.
Andrew Boff AM, said:
"I set out to test the idea that building more family-sized homes would tackle overcrowding more effectively and found that while this is not the only answer, it is without doubt part of the solution.
"Overcrowding is a largely hidden problem but there are literally tens of thousands of families in London suffering the serious consequences of living in cramped conditions behind closed doors.
"Even in a climate of policy reform and limited funding, prioritizing overcrowding and building a larger proportion of bigger homes is the best way to cut costs in the long run, and improve Londoners' lives."
The report acknowledges the need for some smaller homes to help tackle homelessness and take people out of temporary accommodation, which costs London boroughs hundreds of millions of pounds a year. Dealing with temporary accommodation cost the City of Westminster nearly £69 million alone.
But it is a matter of balance, and tackling overcrowding not only cuts the associated costs, but frees up more homes for all size households. Boroughs are urged to amend their allocations policies to give housing associations the flexibility to move existing under-occupied or overcrowded households when vacancies become available, instead of always filling voids with a single household from the waiting list.
The Mayor should also include a specific requirement for 4+ bedroom homes in his targets - instead of his current 3+ target - for new social rented housing, to reflect the fact that around 40 per cent of households in need require this size home.
The report calls also calls on the Government to use its forthcoming social housing reform legislation to make the more 'human' bedroom standard the statutory requirement for measuring overcrowding. Current statutory overcrowding standards - which deem kitchens suitable sleeping accommodation in some cases - were introduced in 1935 and have not changed since.
The main body of the work for the report was undertaken before details of the Government's housing and benefit reforms were known. While the proposals do not detract from the report's conclusions, the challenges and opportunities presented by them in terms of delivering more large homes remain to be seen. The Committee will conduct follow-up work as the policy changes play out.
The Committee's report is based on 49 written submissions and 9 meetings with 12 stakeholder organizations.
Health implications include increased risk of ill health and disability. Children in overcrowded housing are up to ten times more likely to contract meningitis than children in general; there is a direct link between childhood tuberculosis and overcrowding. Delayed cognitive development and mental health issues such as anxiety and depression have also been linked to overcrowded and unfit housing. Overcrowding also imposes a number of financial costs on local and central government. These include providing additional health services, the cost of welfare support resulting from poor educational achievement and the resulting impact on employability and even the costs of anti-social behavior that are linked with overcrowded housing.
Overcrowding is worse in social rented housing than other tenures and London has 44 per cent of England's overcrowded households in this sector. One in three children in social rented housing is living in overcrowded conditions. 102,000 social rented households were considered overcrowded in 2008. Between 1998 and 2008 the number of people living in overcrowded conditions has increased by a third.
Boroughs, under pressure from the costs of providing temporary accommodation tend to quickly nominate any vacancies to households on their waiting lists. Figures from the Chartered Institute for Public Finance and Accountancy ( CIPFA ) show that in 2009/10, 24 London boroughs spent £417 million on providing temporary accommodation - an average of more than £17 million per borough. Dealing with temporary accommodation cost the City of Westminster nearly £69 million alone.
The bedroom standard is an alternative way of defining the size of property a household needs that is commonly used by RSLs which takes into account the age, sex, marital status and relationship of household members.