AI-led strategy for a tricky infill site in Harborne
Lapworth Architects were appointed by a private residential client to test the potential of a tight side-garden plot in Harborne. The aim was to use an outline planning application to establish whether a small residential scheme could be accepted in principle, before committing to full design development. For clients searching for architects in Harborne and the wider Birmingham area, the project shows how constrained infill plots can be assessed quickly and defensibly, using clear planning logic and evidence-led massing.
The site reads as an underused strip of land between two existing flat blocks. It sits within a typical suburban street pattern of simple rectangular buildings, shallow front gardens and parking taken directly from the carriageway. Rear gardens are deep, boundaries are close, and neighbouring windows are present on both sides. In this context, any new volume has to sit quietly between its neighbours while respecting daylight, outlook and privacy.
Project at a glance
- Location: Harborne, Birmingham
- Plot type: tight side-garden infill site between existing flats
- Planning route: outline planning application to confirm principle of development
- Scale tested: one and a half storeys
- Approx. internal area tested: 72 sq m
- Private rear garden tested: 45 sq m
Understanding the constraints early
On sites like this, the usual planning risks are predictable. Overbearing mass, loss of light, overlooking and an uncomfortable relationship to boundaries tend to generate objections quickly. The brief here was straightforward: unlock value without provoking those issues, and produce a clear, council-ready argument that the principle of development is sound.
Key design moves followed directly from the site geometry. The massing was kept to one and a half storeys, with the ridge stepping below the adjacent two-storey blocks. This was done to protect outlook from neighbouring windows and to keep the proposal subordinate within the street scene. The plan logic prioritised primary rooms facing the street and the rear garden, rather than side boundaries, to reduce privacy conflicts and make the internal layouts workable on a narrow plot.
The front elevation was developed to pick up the street’s established rhythm, using a simple entrance bay and grouped windows rather than a busy façade. The intention was to produce a calm, familiar form that sits comfortably between the existing blocks, rather than drawing attention to itself.
AI and AskArchi in the option testing
AI and AskArchi were used as part of the early-stage testing, alongside normal architectural judgement. Working from massing studies, we iterated multiple envelope options over the same footprint and compared them against key constraints, including separation distances, overshadowing behaviour and internal layout efficiency. This helped narrow the options quickly and supported a clear decision on the preferred massing shown in the 3D views.
The outcome of this stage was not design by tool. It was a faster way to evidence that a modest, well-proportioned infill building can sit between existing flats without creating unreasonable overlooking or falling outside common daylight expectations, even on a constrained plot.
Outline planning strategy
The planning route was structured around an outline planning application. This approach asks the council to determine the principle of residential development, while reserving detailed matters such as appearance, layout and landscaping for a later stage. For tricky infill sites, that sequencing can be a sensible way to reduce upfront risk and cost, particularly when the first question is whether development is acceptable at all.
Digital submission workflow
Working through UK Planning Gateway, we coordinated drawings, analysis graphics and supporting statements in a single workflow with consistent version control. This is especially useful on infill sites where survey information and consultant input can evolve during the application process, including highways, drainage and daylight considerations. A coordinated package reduces avoidable validation issues and keeps the submission clear to review.
Architects in Harborne and architects in Birmingham
This project is a clear example of our approach to tricky infill sites as architects in Harborne, and as architects in Birmingham more broadly. We focus on scale, neighbour relationships and a planning argument that grows directly from the constraints of the site. The same approach applies across nearby areas such as Edgbaston and Solihull, where modest, carefully scaled schemes can add homes to established streets when the massing is disciplined and the evidence is clear.
FAQs
Can small or awkward plots in Harborne be developed?
Yes, where the proposal respects daylight, privacy, scale and local character. The key is to test massing and neighbour relationships early and support the outline case with clear evidence.
Why use outline planning for a constrained infill site?
Outline planning can confirm whether residential development is acceptable in principle, while reserving detailed design for later. This can reduce cost and risk when the site’s constraints make the outcome uncertain at the start.
How does AI help on tricky infill plots?
AI-supported tools can speed up early option testing, including massing comparisons, daylight-related checks and layout iteration. Used properly, it helps teams reach a defensible preferred option sooner, with clearer supporting material.
