1.39 The massing of a development must be the outcome of a comprehensive design process that takes account of sustainability early in the design process. This is typically demonstrated through the Design and Access Statement. Applicants should use the site analysis gathered for D01 to determine an appropriate design response.

1.40 Building form should reflect the form factor for appropriate typologies set out in the LETI Climate Emergency Design Guide.

1.41 Designs with excessive stepping forms to maximise development area will likely not be supported as they will have a higher form factor and appear overly complicated and incoherent in appearance (see Fig.16).

1.42 The massing of development should form a gradual transition between different scales or character areas. Changes of scale can be managed across streets and open spaces. Sudden changes in scale and massing between adjoining plots of land are discouraged as they do not contribute towards creating a cohesive place.

1.43 Policy DP12 Tall Building and building heights in the Bexley Local Plan states that the proposed height of buildings should respond to the context of the area and have regard to other design factors including scale, form, proportion and its relation to other existing, consented and proposed structures. Further guidance on the design of tall buildings will be provided in the emerging Area Types document that will form Part 2 of the Design Guide SPD.

1.44 Maximum acceptable building heights are defined in Policy DP12 in the Local Plan (see Fig.15). Fig.18 sets out how to measure building heights. Applicants must indicate the overall height of proposals on submitted drawings.

1.45 The building form should respond to analysis gathered for D01. Close referencing of roof forms, roof pitches, datums and massing proportions within new developments can mediate and enhance visual relationships between new and existing buildings.

1.46 Existing pitched roofs can be considered as a single storey when compared with the heights of flat roof typologies (see Fig.19).

1.47 Corner plots may be suitable to accommodate additional height in some locations. This could be in the form of one additional storey above the established datum of building heights of the immediate context, provided that it does not exceed maximum building heights and it is demonstrated how the design contributes to placemaking and wayfinding in the area and this additional height does not affect the amenity of neighbours.

1.48 On large sites of over 50 dwellings it is possible to create new character areas. Proposals should provide a suitably wide variety of dwelling types and streetscapes to form a successful place. The choice and placement of these building types should respond to the site constraints and opportunities.

1.49 Development should optimise the use of land through a design-led approach. The capacity of a site should be tested using the methodology outlined in Optimising Site Capacity: A Design-Led Approach LPG.

1.50 Optimising does not mean maximising development. New buildings must respond to their physical context and consider the capacity of local infrastructure necessary for new homes and other uses.

1.51 This is as relevant to the conversion of existing buildings as it is to proposals for new development. For example, the conversion of existing single family homes to multiple occupancy can impact the character and amenity of that area, its services and facilities and must be fully considered. This means that in different areas physically identical sites might require a wholly different design response.

1.52 Applicants must also consider how the capacity for growth will be influenced by improvements to supporting infrastructure.

1.53 The guidance in this document sets out how development can come forward depending on whether it will Maintain, Enhance or Transform the area it is in. This advice is however, general and is based on the most common conditions found in the borough. The applicant must ensure the surrounding context is considered in all development proposals.

1.54 Applicants submitting development proposals that go against the advice set out in this document must provide sound justification for their design approach.

Applicants should identify which principle of growth applies:

1.55 Proposals should have a positive relationship to the form, function and quality of surrounding streets, spaces and buildings. This should be achieved through the placement and orientation of buildings and the design of building elevations

1.56 The size of spaces around buildings should be proportionate to the height and massing of surrounding buildings. This should be informed by potential effects upon the microclimate of these spaces

1.57 Consideration should be given to addressing isolation and loneliness through the design of the streetscape. Developments should shape spaces that encourage social interaction

1.58 Applicants should assess the character and function of the streets and spaces within and around the selected site using the tools outlined in D01

1.59 The Design and Access Statement must demonstrate how the design responds to site conditions and/or forms appropriate new streets where required as part of the development.

1.60 Established building lines should be respected and followed to create a consistent street scene if such exists unless there is convincing justification for an alternative approach. Where gaps exist in the rhythm of frontages, new development should look to address these gaps.

1.61 Where a strong rhythm of windows and doors exists within a street, new development proposals should attempt to follow established proportions and dimensions.

1.62 The width of the setback of a building frontage from the street should reflect the predominately suburban character of Bexley. In many parts of the Borough outside of Town Centres this will mean that building frontages up to the street boundary are generally inappropriate unless it is continuing an established building line.

1.63 Greater variation in built form and scale is more appropriate within designated Town Centres where minimal setbacks of building frontages to the street are also likely to be more appropriate.

1.64 Consideration should be give into established historical streetscapes in the Borough. The design of elevations and views from each direction along these streets should be assessed in relation to their historical status.

1.65 Larger setbacks are required along rivers and culverts and next to sites of high natural value - refer to D35.

1.66 Further information specific to Town Centre development, historical streetscapes and development next to water bodies will be provided in the Area Types document that will form Part 2 of the Design Guide SPD

Figure 22 - The form and massing of new buildings must respond to the scale of existing and proposed streets

Figure 23 - Development should follow the established rhythm of the streetscape and address gaps in the building frontage and, where appropriate, create prominent corners within a Town Centre

1.67 A view is composed of the viewpoint; the foreground and middle ground, the focal point, and the background. Development must not intrude upon the foreground or middle ground and must not harm the view composition if in the background.

1.68 Proposals should maintain and/or help to establish views of prominent buildings and features, including those that have not been officially designated. The Character Appraisal in D01, townscape assessments and visual impact assessments should identify locations in the wider urban context where the site will be visible from.

1.69 Applicants must provide visual documentation to justify the effect of proposals upon locally significant views including those identified as significant through the planning process.

1.70 Townscape assessments must include visualisations of the proposal in the context, in both winter and warmer months. VuCity compatible models should be provided for schemes that will have a significant impact on the townscape.

1.71 A relationship with the Borough’s rivers and open spaces is one of the defining characteristics of Bexley. Developments that maximise opportunities to provide and maintain long views, enhance views of vegetation, open spaces and rivers, and provide visual connections to heritage assets from both new and existing homes and public spaces will be encouraged. Applicants can demonstrate this by providing visualisations supporting the design.

1.72 A blank frontage is a wall with no openings or defining features that does not provide any visual interest or passive surveillance to the street.

1.73 The placement of openings should not prevent development coming forward in future to complete an established urban block. If a proposal is adjacent to a site that is suitable for development, designs must avoid placing windows looking over the boundary as this may result in gaps between buildings.

1.74 Where blank frontages are proposed, it must be demonstrated that this is a proportionate, positive and typical feature in the surrounding urban context.

1.75 Blank walls may therefore be appropriate if they form a flank wall that will be covered by a later phase of development. If the future development is speculative, the material treatment of the wall should be of suitable quality as set out below.

1.76 Where blank frontage is justified, applicants must demonstrate that the material treatment of the wall provides suitable visual interest to adjacent streetscapes or public spaces. Blank frontage consisting of the same material and/or colour in the same plane with no detailing will likely not be supported unless the materials are of a high specification.

1.77 Blank walls that are created due to changes in level or steep topography should be avoided. Applicants must consider from the initial stages of the design how to arrange the site to minimise large blank walls. Where retaining walls are needed, these should be designed to be harmonious with the landscape character.

1.78 In some cases, blank walls are a positive feature in the streetscape, such as brick flank walls at the end of a terrace. In these cases, it should be demonstrated through the Character Appraisal that this is a positive, typical feature that can be replicated in the development.

1.79 Where necessary, planting may be used to mitigate against the negative visual effect of blank frontages if the area would be able to support plant life.

1.80 Within Town Centres, blank frontages must be minimised and continuous active frontage must be provided at ground and first floor levels adjacent to high streets and important routes through the Town Centre - see D36.

1.81 Where raised flood defences are required, applicants should refer to the Riverside Strategy Approach set out by the Environment Agency to consider how to address potential blank frontages. Further information specific to riverside development will be provided in the emerging Area Types document that will form Part 2 of the Design Guide SPD.

1.82 The parameters outlined in these principles do not generally apply to Locally Significant Industrial Sites or Strategic Industrial Locations within reason unless the proposed building is not industrial in use. Further information specific to industrial development will be provided in the emerging Area Types document.

1.83 Private amenity space should generally be placed to the rear of buildings rather than along the street to avoid fencing being installed by residents for privacy reasons.

1.84 If fences are provided, these should be permeable for small mammals such as hedgehogs. Gaps should be 13x13cm to allow wildlife through but maintain security in gardens for pets.

Figure 28 - Applicants must ensure development does not create excessive areas of blank frontage