Supporting documents for a single house on a garden plot

One house on a garden plot is a minor application, and the document pack is still longer than most people expect. The backland development documents that decide these schemes are the access drawing, the tree survey and the drainage statement. Policy principle is rarely the fight. The fight is whether a car can get in and out safely, whether the trees survive, and whether the two neighbours either side keep their outlook.

Residential gardens are not previously developed land in national policy terms, so there is no brownfield presumption to lean on. The application has to succeed on the character of the plot and the effect on neighbours.

What the council assesses on a garden or backland plot

Start with the local plan. Most authorities have a design or housing policy dealing with infill and backland sites, usually asking whether the plot respects the prevailing pattern of development, whether the new house has a usable garden and parking, and whether the existing house is left with enough amenity space.

Plot depth is the usual sticking point. A tandem plot behind an existing house creates a driveway running past habitable windows, and officers look hard at noise from car movements and headlight sweep late at night.

Build a short site appraisal into the Planning Statement covering the character of the street, the plot widths either side, the building line and the garden depths. That appraisal is what turns a bare application into an argument.

Access, visibility and highway evidence

The highway authority is a consultee, not the decision maker, and its response usually decides the outcome anyway.

You need a drawing showing the access width, the visibility splays in both directions measured from a set-back point, the turning area inside the site so a car can leave in forward gear, and the bin presentation point within the distance the waste service will accept. Manual for Streets sets out the approach to visibility on lower speed residential roads and is the document to cite.

Where the access crosses a footway you will also need a dropped kerb, which is a separate consent from the highway authority and is not granted by the planning permission.

For a single dwelling a full Transport Assessment is disproportionate. A short access and parking statement inside the Planning Statement is normally enough, with a formal Transport Statement only if the council's validation list asks for one or the access is unusual.

Trees on and adjoining the plot

Garden plots have trees, and often the best ones sit on the boundary in someone else's ownership.

Commission a survey to BS 5837:2012 early. It records each tree by number, species, height, stem diameter, category and root protection area, and it produces the constraints plan the house is then designed around. For a single stem, the root protection area is calculated from the stem diameter and drawn as a circle, which can be modified in shape but not reduced in area without justification.

If any tree is protected by a Tree Preservation Order or stands in a conservation area, the survey becomes load bearing. An Arboricultural Impact Assessment and tree survey then has to show the effect of the new footprint, the driveway construction and the service runs on those root protection areas, with a tree protection plan and an arboricultural method statement for anything within them. The detail of that position is set out in the guide to which reports a site with a Tree Preservation Order needs.

No-dig construction for driveways inside a root protection area is normal on these plots. Design it in rather than promising it as a condition.

Ecology and the biodiversity gain position

A garden plot usually holds hedges, lawn, shrubs and sometimes a shed or garage with bat potential. That is enough to need a Preliminary Ecological Appraisal on most sites, and a bat survey if any building with roosting potential is being demolished or reroofed.

Biodiversity net gain applies to small sites, with a de minimis exemption where the development affects less than a small stated area of on-site habitat and no length of hedgerow above the stated threshold. Check the current figures on the GOV.UK guidance before assuming an exemption applies, and note that self-build and custom build schemes have their own exemption with conditions attached.

Where net gain does apply, the statutory metric has to be completed by a competent person and the biodiversity gain plan approved by the council after permission. A Biodiversity Net Gain Assessment drafted in PlanScope gives the structure and the policy framing, and the metric calculation itself is work for a qualified ecologist under the Environment Act 2021 regime.

Drainage on a plot with no obvious outfall

Backland plots often sit behind the house with no frontage, no gully and no obvious connection. The drainage hierarchy still applies: infiltration first, then a watercourse, then a surface water sewer, then a combined sewer as a last resort.

Infiltration means percolation testing, and the results either support a soakaway or they do not. Clay subsoils and high groundwater rule it out on plenty of sites, at which point you are negotiating a connection with the sewerage undertaker.

Foul drainage needs its own answer. A long private run to the public sewer across a shared driveway raises maintenance questions that the neighbours will raise for you.

A short Drainage Strategy covering both flows, with the percolation results appended, deals with this cleanly.

Amenity evidence for the neighbours either side

Two houses look directly at a garden plot, and their objections will be about overlooking, loss of light and the driveway.

Deal with each on the drawings. Show the separation distances to facing windows. Show which windows are obscure glazed and non-opening below a stated height, and put that in the proposed elevations rather than offering it as a condition. Where a boundary is tight, a 45-degree line drawn in plan and section from the nearest neighbouring habitable window is a useful illustrative check that officers recognise, and it should be drawn before the design is fixed rather than afterwards.

The driveway needs the same treatment. Draw a section through it showing the boundary treatment, and say what the surface is. A gravel drive alongside a bedroom window at two in the morning sounds different from a bonded surface, and an officer who has read an objection about noise will look for that detail.

Garden size is the quiet refusal reason on these plots. Check what the existing house is left with once the plot is carved off, and check the new house against whatever amenity space standard the local plan sets. A scheme that leaves the original dwelling with a strip of garden it cannot use is refused on the effect on the existing occupiers, and the applicant rarely sees it coming because they are thinking about the new house.

Bin and cycle storage belong on the block plan too. Both get conditioned if they are missing, which delays the start on site.

The document pack for one dwelling

For a typical garden plot with trees, no flood risk and a shared access, expect to submit:

• Application form, ownership certificate and, where the access or garden is in other ownership, the notice served under the form requirements
• Location plan at 1:1250 with the site edged red, and a block plan showing the access
• Existing and proposed floor plans, elevations and at least one site section through the tightest boundary
• A Planning Statement covering policy, character, amenity, access and drainage
• Tree survey, arboricultural impact assessment and tree protection plan to BS 5837:2012
• Preliminary Ecological Appraisal, with bat survey results if a building is affected
• Biodiversity net gain metric and statement, or a written case for the exemption relied on
• Drainage statement with percolation test results
• The council's own additional validation items, which is where local lists differ most

A Design and Access Statement is not required for every minor application. It becomes mandatory for development in a conservation area involving one or more dwellings, and for listed building consent, so check the site first.

Commission in this order: tree survey, then percolation tests, then ecology, then the design. Doing the design first and the surveys second is how garden plots end up redrawn twice.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.