In the Go-Between (1953) LP Hartley suggested that, 'The past is a foreign country, they do things differently there'. It is equally true that the future will be a foreign country where things will be done differently. In that sense we are all migrants from an uncertain present to a future that we hope will include answers to our various problems and crises. I hope that both cynics and sceptics will show some patience and give cusping a chance and this is why...
As the idea of custom splitting is discussed, the benefits and challenges both become clearer. This is the latest description - with apologies to those readers who would like to hear something completely different.
All parties with an interest in how the planning system works (from the Chancellor of the Exchequer down to the rough sleeper in the shop doorway) should be looking for ways of sharing out the existing stock of housing before simply adding to the supply. Until ways to re-distribute this scarce resource have been fully explored the need for new housing cannot be objectively assessed or known.
The case for custom splitting
The idea of 'custom splitting' (cusping) has been out there for long enough to know that it can meet individual circumstances and add to the overall housing stock with minimal building works involved. However, there are a growing number of reasons to believe that local planning authorities should be encouraging cusping in order to move it into the mainstream in the provision of ‘new’ housing.
Planners should be addressing the challenge of finding ways to house people in existing urban areas and closer to existing facilities and services than on peripheral estates. Matthew Carmona (Thinking small to think big TCPA August 2017) was arguing for an increase in urban densities by building on small sites and adding storeys in order to meet the need for new housing in London, describing a process of ‘proactive densification’ as a ‘generational challenge’, and one with the co-benefit of helping smaller builders. These are important matters but barely touch on the full range of benefits that could be derived from a concerted attempt to systematize custom splitting.
The Government and opposition parties appear to be equally concerned about the failure to increase the rate of delivery of new housing. In support of the legislation adding the duty to provide serviced plots to the requirement to keep registers of individuals and associations of individuals the Government is making substantial grants available. However, getting from the current 7.7% of the new built homes being completed each year (<15,000) to closer to 20% of 300,000 which are said to be required( ie 60,000), is unlikely to happen without a significant level of cusping. The Bacon Review addressed in a 2021 blog is unlikely to move the dial, and does not refer to sub-divisions.
The level of under-occupation of both bedrooms and living areas in the existing housing stock (even in Inner and Outer London) is far greater ie over 50% than the levels of overcrowding ie less than 10%. The potential of cusping was looked at in 2016 by the Intergenerational Foundation estimating that there could be 4.4million dwellings readily available for sub-division. In 2016 the All Party Parliamentary Group for the Care and Housing of the Elderly received evidence that there could be as many as 8 million households looking to downsize were attractive smaller dwellings made available. This emphasizes the need to increase the supply of housing suitable for the elderly that is unlikely to be met even if all the 200,000 new dwellings that the industry might be capable of providing each year were dedicated to that sector.
The Intergenerational Foundation has revisited the issue of under-occupation in Stockpiling Space https://www.google.com/url?q=https%3A%2F%2Fintergenerationalfoundation.cmail20.com%2Ft%2Fr-l-triikjlk-ukiddlliuh-w%2F&sa=D&sntz=1&usg=AFQjCNHOE45mV4G7w5KkSl1-Eox2Lsp1wQ
By normalising sub-divisions through custom-splitting an important step would be taken to sub-dividing properties into more 'units' in expanding the choice of co-living in other forms. This could be seen as a form of multi-occupation, but would imply all residents having a share or stake in the property and its equity.
Demand for renewable electricity from road transport and manufacturing (including MMC for housing) will increase over the next decade. This will require the space and fabric of existing housing that is being insulated and heated/cooled to also be occupied to meet genuine housing need and, incidentally, reduce the need for new building with the high levels of embodied carbon and loss of biodiversity and soils. In 2022 the Environment Audit Committee complained that the embodied carbon in new housebuilding is being ignored and meeting Government new build targets (recently being softened if not reduced) would consume the whole carbon budget for all sectors.
The benefits of cusping, some of which have already been touched on, would include:
- Reducing unsustainable levels of under-occupation in urban, suburban and rural areas.
- By making energy upgrades a condition of granting planning permissions or Local Development Orders, the existing housing stock (excluding registered providers with generally higher standards) of which 80% is currently at the equivalent of EPC D or below could be upgraded to EPC B and above. This would reduce the possibility of either household falling into fuel poverty. Works involved in subdividing properties would be little or no more disruptive than the necessary deep energy refits.
- Cusping would enable older households to downsize-in-place in what could evolve into a Lifetime (or 15min) Neighbourhoods. This could also involve adaptations of all or part of the property to Lifetime Home standards avoiding the perverse incentive to continue to live in an unnecessarily large home.
- In the choosing of partners and the designing the accommodation, the process of cusping could include the respective households seeking to meet their current and foreseeable needs in terms of caring for children, the sick, disabled or elderly (obviously on the understanding that personal circumstances are subject to change).
- The choice or partners would involve matching financial needs, but also the other resources and skills that could be shared and acquired and contribute to the efficient and cost effective implementation of the sub-division. As with custom-building the principle is in the customised design and...
- However proficient the parties, many projects are likely to create some work for smaller tradesmen and builders (some laid off from the reduced need for new building).
- The parties could negotiate and choose how the garden could be subdivided in the short and longer term (without building on it) allowing ageing households to maintain a larger garden that is normally available with smaller properties and those designed for the elderly. This form of ‘downsizing-in-place’, overcomes the under-estimated problem/excuse of clearing the loft of stuff that can be concentrated at one end.
- Both parties would be able to negotiate and choose between renting and buying all or part of the respective parts, some being intentionally shared (eg accesses, garden areas, garages or sheds). Rent-to-buy could be popular model.
- The original owners could release equity without re-mortgaging or taking out high interest loans – renting out the separated dwelling could provide an income, possibly through rent-to-buy. This might make custom building (through splitting) accessible to the younger generations which are currently being excluded due to the high upfront costs.
- The density of people (potential custom for local services and facilities) would be increased without building on open land (some brownfield land has become very bio-diverse), including gardens.
- The issues surrounding the non-implementation of planning permissions being experienced in the new-build sector would be avoided as custom building of all types effectively conflates supply and demand.
- The works involved in sub-dividing properties represent a very efficient use of materials and labour that are both increasingly scarce and expensive, especially following Brexit. It would be more expensive to buy part of an existing plot but should be much cheaper to complete a conversion to self-contained dwellings than to start on a bare site,
- By matching those with spare space that they are willing (and keen) to share with those on the Registers, LPAs would have a reasonable chance of meeting their legal duty to provide serviced plots,
- Cusping at scale would provide a 'realistic alternative' to supply housing that should be fully explored before permitting new building in Green Belts.
- Residential sub-divisions would also reduce the pressure to develop peripheral estates in the open countryside.
- Sub-divisions providing self-contained accommodation would be consistent with the proposal to change the General Permitted Development Order to allow upward extensions without express permission so long as a separate/additional dwelling would be created.
- The works of sub-dividing a property into two or more self-contained dwellings is subject to a reduced rate of 5% VAT even if not the zero rate applicable to new build.(the Chancellors 2022 Spring Statement reduced the VAT rate on most insulation products).
Some of these 17 potential benefits of cusping at scale; addressing the shortage and/or distribution of housing, increasing energy efficiency of buildings and addressing fuel poverty, potentially providing social care (even if just through good neighbourliness), are non-trivial and represent a form of 'sustainable development', and more so than probably all forms of residential new build. In the current jargon, custom-splitting should be seen as the ultimate in "co-production" that implies extra challenges but, hopefully, even more benefits and rewards.
Helping it happen
The central government grants available for custom-building should be made available for cusping. LPAs persuaded of the benefits of cusping should be prepared to make grants available to cover the upfront costs associated with the feasibility, design and/or conversion that could be recovered either on completion of the works or as a charge on the property that would be repaid on its later sale. Policies in local plans should set out the circumstances when cusping would be supported (or opposed?). This could be greatly simplified through the making of Local Development Orders (eg specifying energy standards and minimum room sizes). Registers should be kept of property owners wanting to be introduced to those on the custom building registers who should also be asked to include their willingness to engage in the sub-division of an existing property rather than wait for up to three years if they are lucky enough to even receive an offer of a serviced plot at an acceptable location and price.
Those engaged in selling/renting houses should introduce a 'new' service by selling/renting parts of properties.
Councils and housing associations could designate/reserve houses to act as safe havens while a property was being sub-divided and given a deep retrofit and mobility upgrade.
 This article is not about HMOs which are probably the most common type of sharing but with less privacy and independence than provided by cusping.
 Now Self and Custom Housebuilding Act 2015 (as amended)
 It will not help in practice to call a peripheral estate a “sustainable urban extension”
 A nod towards the co-housing movement which is also needing help from the planning system
 Unlocking England’s Hidden Homes (http://www.if.org.uk/wp-content/uploads/2016/03/Unlocking-Englands-Hidden-Homes_Final.pdf)
 Local Planning Authorities can adopt Local Development Orders in order to make residential sub-divisions ‘permitted development’ subject to conditions or prior notification including energy standards and minimum space standards
 The ‘consequential improvements’ proposed and then withdrawn (when branded a conservatory tax) by the 2010 Coalition Government was the last attempt at maintaining if not upgrading the housing stock