SPD

34. Other Types

34.1. Conversion and extension

If your site falls under the conversion and extension site type there is advice available in a number of places.#

The first place to look will be if your site falls into another site type. Conversions and extensions will almost always also sit within either the infill or backland category as well.

It is important to consider conversion and extension as part of infill or backland development as retaining existing structures is vital to helping the building industry respond to the climate emergency we are facing.

Alterations and Extensions SPD
When working with existing buildings, extensive advice is available in the Alterations and Extensions SPD that is available from the Lewisham Council website.

This document provides advice on how to extend buildings both vertically and horizontally. The advice in this document focusses on enlarging existing dwellings, but the principles set out will also apply to the extending and converting of existing dwellings in order to create new homes as part of a small site development.

34.2. Garden land

As set out in the Local Plan, the development of garden lands should be avoided as they “make an important contribution to local character and amenity and often have ecological value. Development on garden land should therefore be avoided in favour of development opportunities elsewhere in the borough, particularly on brownfield sites and previously developed land, consistent with the spatial strategy for the borough.”

Infill and backland characteristics
When working with garden land it is important to consider if it can be classified also as an infill or backland site which are more favourable development opportunities. It is therefore key that garden sites have clearly distinct access arrangements, such as a street frontage or mews / lane access, and do not rely upon passing through the demise of another property.

Having at least one street frontage makes a site significantly more favourable.

Mitigating losses
The Local Plan also states that the garden development should only be considered “where appropriate re-provision of garden land is provided to mitigate losses as much as possible.” As such, when developing garden land re-providing, or working around, the important role that existing gardens play is important, including their role in providing biodiversity and habitats.

34.3. Amenity

As with garden sites, amenity land provides an important role in the borough and therefore should be considered carefully before putting it forward for development.

In order to develop these sites applicants will need to prove that the amenity function of the site is either no longer required or is oversupplied in the area and therefore not needed.

If the amenity function can be proven to be redundant then applicants should identify the other characteristics of the site as most amenity sites will have characteristics of either infill or backland sites. Once this has been identified, applicants will be able to find advice from the corresponding site type section in this document.

33. New Mews and Alleys

33.1. General principles

Mews and alleys are a common feature of Lewisham, with many such examples found across the borough.

For the purposes of this document mews and alleys are considered to be continuous narrow passageways which are accessible from the public highway at both ends. Sites which are accessible from only one end generally fall under the definition of “garages and yards” and in this case the guidance for that section applies.

Historically mews and alleys will have been used to provide service access to the rear gardens of properties facing the street, and many feature outbuildings and garages facing directly onto the mews. Consequently they can fall under multiple ownerships or with rights of way, so permanent access for the purposes of development can be difficult to secure.

Piecemeal development along mews and alleys, including the conversion of existing workshops and outbuildings into new dwellings, will not be supported.

Where street-facing sites exist at the entrance to mews and alleys, development may be possible in line with street extension principles (see section 27).

New street-facing dwellings can act as a catalyst for further development along mews and alleys, but this should come forward in an coordinated way. That is not to say that all mews development should appear identical in character – in fact a variety of architectural styles is an attractive characteristic of such development – but that where new homes are proposed the installation of appropriate infrastructure (such as utilities, road surfaces, artificial lighting and so on) should be in place prior to development taking place. The use of pre-commencement planning conditions could be used to ensure that such provisions are in place at the appropriate time.

Any development along mews or alleys should ensure that sufficient space is allowed for the safe movement of pedestrians and vehicles. In most cases mews which are narrower than 6m will not be supported. The use of shared surfaces is required, and proposals which include a separate pavement and roadway will be resisted.

Due to the length of many mews and alleys found in Lewisham, development beyond the first 40m is unlikely to be acceptable due to the limitations of waste collection. This can, in some cases, and if there are sufficient homes to justify it, be extended to 60m where waste collection vehicles are able to reverse safely up to 20m into a site (see figure 184). Where this is being relied upon, applicants will be required to provide evidence (through tracking diagrams, or similar) to demonstrate that waste collection vehicles can undertake safe and efficient manoeuvring without endangering pedestrians.

Where a high-quality road surface, artificial lighting, right of way, and sufficient turning capacity can be secured along the full length of the mews or alleys – from public highway to public highway – coordinated development along its full length may be acceptable where it is of sufficient width to allow access for waste, delivery and emergency vehicles, and for pedestrians to pass safely.

Occasional gaps between buildings are a characteristic of many mews developments, providing long views for homes within them and planning applications for such schemes should demonstrate a thorough understanding of local context and character. Design and Access Statements explaining how mews development responds to local character should accompany any submission.

Gates across the entrances to mews and alleys will not be permitted, although rising bollards or other methods of controlling vehicle access which do not inhibit pedestrians are allowed where appropriate.

Acceptable privacy distances can be difficult to achieve when new dwellings face one another across a narrow mews or alley. In these cases flexibility can be applied to the requirement for privacy distances, although steps should be undertaken to ensure that residents’ enjoyment of their homes and their right to privacy are not compromised to an unacceptable degree. Staggered windows, the use of projecting windows, that limit direct overlooking by focussing outlook sideways or upwards, or sloping roof windows can be employed to achieve these objectives and applicants will be expected to demonstrate how adequate privacy is achieved.

Where development is proposed within Conservation Areas, the accompanying character appraisal takes precedence and applications should demonstrate how proposals are in accordance with it.

32. Garages and Yards

32.1. General principles

Disused garages and yards often occupy space between the end of long gardens within urban blocks, and are usually reached via a narrow access from the public highway.

In many cases such garages have fallen into disrepair as they are no longer large enough to accommodate modern cars, and can be a source of anti-social behaviour.

Planning applications which propose the replacement of existing garages or workshops will need to demonstrate these structures are no longer required. A parking survey may also be required.

Where backland sites are occupied by non-residential uses, the change of use to residential will be resisted unless sufficient allowance is made within the scheme for these uses to continue. Where the development itself will involve the temporary disruption of non-residential activities, assurance may be sought that temporary relocation of any businesses occupying the site is secured, and that provision for their return once work is completed has been made.

The development of new homes on such sites can bring benefits to adjoining residents, including increased security.

Where a site has more than one access point from the public highway it is defined as a mews rather than a garage or yard site. See the appropriate section of this document for specific guidance on mews sites.

Where development is proposed within Conservation Areas, the accompanying character appraisal takes precedence and applications should demonstrate how proposals are in accordance with it.

New residential development on sites previously occupied by garages and yards should make adequate provision for safe access for pedestrians, including artificial lighting, even road surfaces, passive surveillance and, where necessary, sufficient width for vehicles and pedestrians to pass one another without pedestrians having to step to one side.

In areas of Lewisham which benefit from a high level of accessibility to the public transport network, car-free developments will be supported; conversely, developments which propose car parking will not generally be supported, with the exception of spaces dedicated to wheelchair parking.

Where new dwellings are located some distance from the public highway it may be necessary to make an allowance for certain vehicles to enter the site, eg. for deliveries and emergency vehicles. In these cases a turning head should be provided, although steps should be taken to ensure that this is not used as a parking space for residents’ own vehicles.

Under no circumstances will gates across the entrance to access routes into backland development be supported. Rising bollards or similar devices which prevent vehicle ingress, but do not inhibit pedestrian access, are acceptable, providing that there exists a strategy for allowing emergency and other service vehicles into the site where necessary.

Access for waste and recycling collection must be considered from the outset in any design. In general terms, operatives are able to drag waste and recycling bins up to 10m from outside the front door of dwellinghouses, or a dedicated collection point, to the highway.

Where dwellings are proposed with front doors more than 10m from the public highway, a dedicated waste and recycling point should be designed into the development. Residents should have to carry their waste no more than 30m from their front doors to this collection point. In most cases this places an effective limit of 40m between the public highway and the front door serving a new dwelling.

In limited circumstances it may be possible for waste collection vehicles to reverse up to 20m into an access way serving a backland development, however, this depends on the geometry and safety of the junction with the public highway and an adequate width to allow both waste collection vehicles and pedestrians to pass safely. Furthermore, given the complexity of this manoeuvre waste collection vehicles cannot be expected to reverse into backland sites serving fewer than 10 dwellings.

Where insufficient provision is made for the storage of waste, this can result in unhygienic conditions and contribute to a cluttered and untidy public realm.

In all cases early engagement with Lewisham’s waste and recycling team is encouraged to ensure that sufficient provision is made within the layout of the site for this purpose.

In any planning application for backland development where access to new dwellings is reliant on a single route from the public highway, the applicant will need to demonstrate that a high-quality, safe and even surface can be secured. The use of planning conditions to ensure that necessary improvements are implemented prior to occupation of new homes may be applied to any planning approvals. Applicants are encouraged to check, and secure where necessary, the right of way or ownership over any area of the site which falls outside the application boundary.

Due to their proximity and relationship to existing homes, backland development sites must take care to respect the privacy enjoyed by neighbouring properties. New development should avoid, where possible, direct overlooking of adjoining rear gardens, and applications that propose new dwellings where the windows of habitable rooms look directly over the first 10m of existing rear gardens will not be supported.

Within new development itself, privacy and overlooking distances can in some cases be relaxed to ensure the optimum use of a site, although applicants will need to demonstrate how the spirit of the policy is being achieved in other ways.

New development should make efficient use of available space. In most cases terraced or semi-detached dwellings are preferable to detached properties.

The height of new development should generally follow that of the predominant height of the properties surrounding it. In this case, the number of floors is considered to include substantial pitched roofs.

Where development is proposed within Conservation Areas, the accompanying character appraisal takes precedence and applications should demonstrate how proposals are in accordance with it.

32.2. Backland sites and existing employment uses

Many backland sites in Lewisham are occupied by existing commercial uses such as workshops. These premises provide vital accommodation for small businesses, and planning applications for new homes which involve the net loss of employment space will not be supported.

However, where the intensification of an existing site can be achieved without the net loss of employment space, development will usually be supported, provided that all other planning policy requirements are met.

Depending on the nature of the existing employment use, some consolidation may be acceptable, for instance, where single-storey buildings could be replaced by two-storey accommodation without compromising the operational requirements of the incumbent business.

In exceptional circumstances, and where it can be demonstrated that there is no longer a demand for a particular type of employment space, a reduction in floor space may be accepted where the new accommodation is of a superior quality than the premises being replaced. In this case, evidence should be provided that a change in planning use class (for example, from E(g)(i) to E(g)(ii)) will result in not net loss of jobs, and will result in a use which is more in demand in the local area.

The process of redevelopment itself can be disruptive to existing businesses, and where appropriate a guarantee may be sought through legal means to temporarily re-house an existing tenant so that their ongoing business operations are not put in jeopardy by the works.

These sites are often reached by narrow accessways from the public highway. In this case the principles set out on the preceding pages should apply.

There should be a clear separation between the residential areas and the commercial uses. Vehicles serving the commercial buildings should not have to pass through a residential zone. Likewise, access to new homes should not be through the non-residential zone. Shared accessways from the public highway will be accepted. In these circumstances special care should be taken in the design of shared surfaces to ensure that they are safe for pedestrians.

31. Backland

31.1. What is backland development?

Backland development takes place on sites which are largely landlocked by surrounding development.
Such sites might be occupied by existing garages, redundant workshops or unused open space, and generally fall into one of two categories:

• Garages and yards
• Mews and alleys

Garages and yards are defined by backland sites which are accessed via a single passageway from the public highway. Any vehicles entering the site must turn within it and leave via the same way they came in.

Mews and alleys are a common feature across Lewisham, and usually comprise long, narrow passages which can be accessed from both ends. These are typically used to provide access to the end of rear gardens serving houses around the edge of the urban block, but many remain largely undeveloped.

31.2. What to look out for

Permission for new development on backland sites will not usually be granted where this land is designated as open space, where it has an unusually high biodiversity value, or where it supports existing non-residential uses which are still in operation. However, where sufficient space for such activities can be reprovided as part of a wider development which includes new housing, such proposals may be supported provided that other policy requirements are met.

A key constraint for backland development is access for services, including waste and recycling, deliveries, and the emergency services. Applicants should consider these constraints from the outset as they can have a fundamental impact on the viability of a development proposal. Where new homes are proposed with front doors more than 20m from the public highway, access routes should be wide enough to allow larger vehicles, such as ambulances, box vans and delivery vehicles, to traverse them while allowing safe access for pedestrians. In this case there should also be sufficient space for these vehicles to turn around within the site rather than having to reverse.

Piecemeal development of backland sites is not usually acceptable as adequate artificial lighting and safe road surfaces must be provided between the public highway and the front door of every property. Therefore such developments should usually come forward as a single planning application, and built in a single construction phase. The use of planning conditions or Section 106 agreements may be necessary to ensure that no occupation of new homes is allowed until such provisions are put in place.

Backland sites present an opportunity to achieve high-quality placemaking and a sense of identity. As these sites are often some distance from neighbouring properties, they can often allow a good architect to create a high-quality living environment which is visually distinct from its surroundings.

Backland sites can often incorporate complex site ownerships or rights of way which might not be obvious. A full investigation of such restrictions should be carried out prior to preparing a planning application, and applicants will be required to demonstrate that new dwellings can be safely accessed without the risk of future claims from existing landowners.

Where backland sites include existing non-residential employment uses, the loss of space will not be supported unless it can be reprovided within the new development.

31.3. Backland trees and biodiversity

Trees within backland sites make a significant contribution to both biodiversity and the quality of the public realm. Views of trees glimpsed through gaps between buildings provide important visual interest and depth to otherwise built-up urban areas.

Previously undeveloped backland sites are important for sustaining birds, insects, plants and animals. The development of such sites can have a detrimental effect on local wildlife, so planning applications should demonstrate how a net biodiversity gain will be achieved.

The loss of trees within backland plots to make way for development will be resisted, and planning applications for new homes will need to demonstrate how existing trees will be protected during construction works and how the layout of accommodation responds positively to existing trees. All planning applications for sites with, or close to, existing trees must be accompanied by an arboricultural survey and method statement.

New external surfaces should be permeable wherever possible, and the use of Sustainable Drainage Systems (Toolkit) should be considered where appropriate.

Green or brown roofs can help mitigate the loss of green space and their use is encouraged wherever possible.

31.4. Waste and recycling

Provision must be made for the storage of household waste, and adequate access provided for collection.

Where refuse vehicle access and turning cannot be provided, refuse should be stored no further than 10m from the adopted highway, and no more than 30m from a proposed dwelling. On sites of this type, this means that dwellings can be located up to 40m from the highway.

In some cases it may be possible for refuse vehicles to reverse a maximum of 20m into a development on the basis that turning access can be provided from the highway, and the design of the road junction allows. This increases the distance of the furthest dwelling from the highway to 60m.

This approach will only be accepted where there are a sufficient number of homes within the development to justify it. Early engagement with the Lewisham’s waste and recycling team is advised to ensure that proposals are acceptable.

Where these distances are not achievable, it may be possible to implement a management strategy where waste and recycling is moved from outside the entrance to dwellings to a collection point. Because this will likely result in additional service charges, and is heavily reliant on ongoing management, such an approach will only be allowed in exceptional circumstances. It may be necessary to secure this service through a Section 106 agreement.

All developments with on-site refuse collection will require the road surface to be sufficiently robust to withstand the weight of vehicles. Key dimensions are also required to show that the movement of collection vehicles does not compromise the safety of pedestrians.

31.5. Privacy and overlooking

By their very nature backland sites are usually located in close proximity to the gardens of existing homes. The design of new development should limit, where possible, direct overlooking of existing neighbouring gardens, particularly within the first 10m of the rear of the existing dwelling.

31.6. Access for cars, emergency vehicles and deliveries

Car-free developments will be encouraged in areas with good access to public transport or close to town centres. In most backland developments it will not be necessary for private vehicles to enter, and access only needs to be provided for emergency vehicles, deliveries and, in some circumstances, waste collection vehicles.

Where there is limited access to the public transport network and where sites are some distance from town centres, car parking may be provided within developments. In this case car parks serving new development should be located close to the entrance to the site with the public realm outside new homes restricted to pedestrians only. Proposals which provide excessive quantities spaces, or space for parking within the curtilege of individual homes, will be resisted, except for spaces reserved for those with disabilities.

The fire brigade requires access for a pumping appliance to be within 45m of all points inside the dwellinghouse, or within 18m of a dry fire main inlet. Dead-end access routes longer than 20m require turning facilities. Refer for Building Regulations Part B for more details of the requirements for access for the purposes of fire-fighting.

30. Vertical Intensification

30.1. Introduction

Adding additional floors to existing buildings can provide much-needed new homes in sustainable locations close to public transport, high streets and places of work.

Adding new floors to existing homes can enable new dwellings to be created through a combination of the reconfiguration of internal layouts together with the creation of new floor space.

Note that extentions which provide additional floor space without creating a new dwelling fall into the category of Alterations and Extensions, and are subject to a different Supplementary Planning Document. Please refer to the Council website for the Residential Alterations and Extensions SPD.

Adding new floors to existing buildings can be particularly complex and have a significant impact on neighbouring properties and the character of the street. To this end, the Council advises any applicant wishing to proceed with vertical intensification to contact the Council and seek advice through the pre-application process. Please consult the Council’s website for further details.

The following sections therefore offer general principles and key considerations but should not be read as prescriptive guidance.

Note also that in most cases vertical intensification within Conservation Areas will be resisted.

30.2. General principles

Proposals for vertical intensification must be accompanied by a robust analysis of local context and street frontage to successfully demonstrate that individual intensification will not be harmful to local character.

Consideration must also be given to the impact of new extensions on daylight and sunlight reaching neighbouring properties, particularly those to the rear. The general guidance outlined in section 12.3 should be applied. Where this cannot be achieved, a daylight and sunlight report should accompany any planning application to demonstrate that neighbouring properties are not affected to an unacceptable degree.

The vertical extension of existing properties can set a precedent for wider intensification within a street, although this needs to be managed in a coordinated way to ensure that the intermediate condition does not create a disjointed and inconsistent streetscape.

New homes created through upward intensification must meet the space standards set out in the London Plan, as well as providing adequate external private amenity space – although this can be formed via a subdivision of the existing external private amenity space (such as rear gardens) at ground floor level.

The net effect of incremental intensification can have unforeseen consequences on local services. Planning applications for upward extensions to existing homes will need to show how bicycle storage and waste and recycling collection have been accommodated within the design.

In most cases the net loss of family homes (defined as those with three or more bedrooms) will not be accepted.

Generally, houses that do not benefit from in-curtilege storage for waste and recycling cannot be upwardly extended where this will result in bins cluttering the pavement.

In most cases vertical intensification is inappropriate in Conservation Areas and will generally be resisted. The Council offers a range of pre-application services including advice on infill development appropriate in Conservation Areas.

For any proposed vertical intensification the onus is on the applicant to ensure that development responds positively to the character of the existing property and its surroundings, and is of an exceptional design quality.

30.3. Streets with varied character

Where streets have a varied character and inconsistent height, existing properties may be extended to match that of the tallest property in the street, excluding corner buildings (those which sit on the junction of two public roads).

In certain cases it may be acceptable to extend beyond the tallest property providing the extension is of exceptional design quality and meets all other relevant aspects of planning policy.

30.4. Corner buildings

Generally, corner plots present an opportunity for slightly taller buildings than might be possible within the middle of the street. Vertical intensification may be acceptable on corner buildings to help provide orientation and identity to existing streets. The increased scale should be appropriate to its context and fully justified.

30.5. Apartments and/or detached residential blocks

Existing residential blocks can often provide an opportunity for upward extension to create new homes, providing that access to sunlight, natural daylight and privacy are not compromised to an unacceptable degree within existing dwellings, either in the building below, or those in close proximity.

Planning applications for the vertical intensification of residential blocks should be accompanied by a daylight assessment which demonstrates that adequate natural light reaches all existing and proposed dwellings.

Where new vertical circulation is required outside of the building footprint to meet fire safety or accessibility requirements, these are subject to the same requirements in terms of daylight and sunlight, and justification should be provided to demonstrate how these elements are consistent with the overall design approach.

30.6. Streets that have a consistent height

Where streets have a consistent height and character, vertical intensification to provide additional homes will generally not be supported. The council advises any applicant wishing to proceed with vertical intensification to contact the Council and seek advice through the pre-application process. Please consult the Council’s website for further details.

30.7. Vertical intensification above other uses

Creating new accommodation on top of existing non-residential uses, such as shops, which make a poor use of the available land, area or are significantly lower than neighbouring buildings will generally be supported provided that all other planning policy issues are met.

Note that adding residential uses to non residential buildings can present challenges in terms of access, fire safety and so on, which – while outside the planning process – can have a significant impact on a scheme’s layout and design.

The space above non-residential uses, such as parades of shops, can help deliver new homes in sustainable locations such as high streets and district centres which are usually close to public transport and local amenities.

Sites such as this which are suitable for vertical intensification are often occupied by single-storey buildings. The addition of new floors which create new homes will usually be supported where there is limited impact on neighbouring dwellings.

Where individual commercial units exist within a wider, inconsistent street, the general guidance on vertical intensification will usually apply. However, where adjacent properties can be extended together a greater quantity of new accommodation can often be provided compared to individual owners acting alone.

When new homes are created in the space above existing non-residential uses, care must be given to the design of circulation space, both inside and outside the new development. Single-aspect homes will usually be resisted, and ground floor entrance lobbies should usually be located within a primary elevation rather than concealed along side elevations, unless it can be demonstrated that access is safe, secure and attractive for residents and visitors.

The height of new vertical intensification will be determined by a number of factors including local context, overshadowing, structural bearing capabilities of the host building, and so on. All planning applications for extensive vertical intensification will need to demonstrate how development can be achieved safely and effectively, and how it will provide high-quality accommodation for residents.

Other than to make way for adequate means of access to the new dwellings for residents, emergency services and so on, the loss of employment space at ground floor will be resisted.

Special consideration must be given to the safety of new development in respect of fire: including access for fire-fighting, escape routes for residents and adequate fire separation between different uses. The fire brigade should be consulted as part of any planning application and significant weight will be applied to their analysis in this regard. It is recommended that a specialist fire consultant be engaged at an early stage in the design process to ensure that compliance with the relevant legislation can be achieved.