Report bundle for a single dwelling on an infill plot

One new dwelling on an infill plot is a minor application, and the documents it needs are the national validation list plus whatever your council's local list adds plus whatever the site's constraints trigger. In practice that is usually six to nine documents, and the two that most often hold up validation are the biodiversity information and the drainage information.

Start with the council's own local validation list. It is published, it is specific to that authority, and it is the only document that tells you what will actually be checked on the day your application lands.

What every application carries

The national requirements are the same everywhere in England: the completed application form, the correct fee, a location plan showing the site edged red with any other land in your control edged blue, a site plan at an appropriate scale, the ownership certificate and agricultural holdings certificate, and the community infrastructure levy additional information form.

Add existing and proposed plans, elevations and sections, a block plan showing the relationship to neighbouring buildings, and a street scene elevation where the plot sits in a continuous frontage. That last drawing does more work than any written statement on an infill plot, because the objection you are answering is almost always about rhythm and spacing in the street.

A Design and Access Statement is not required for every minor application, but it is required where the site is in a conservation area or a World Heritage Site and the development involves one or more dwellings. Even where it is not required, on a contested infill plot it is the document that lets you set out the design reasoning rather than leaving the officer to infer it.

Biodiversity net gain on a small site

Mandatory biodiversity net gain has applied to small sites since 2 April 2024, following its introduction for major development on 12 February 2024. The obligation is a minimum 10 per cent gain, secured for at least 30 years, measured with the statutory metric and delivered through a biodiversity gain plan approved by the authority before development may lawfully begin.

Three exemptions matter on a single plot.

The self-build and custom build exemption covers development consisting exclusively of self-build or custom build dwellings, where there are no more than nine dwellings on a site of no more than 0.5 hectares. If you are actually building for yourself, check whether you qualify before commissioning anything.

The de minimis exemption applies where the development does not affect a priority habitat and affects less than 25 square metres of on-site habitat and less than five metres of on-site linear habitat such as hedgerow. A plot carved from a mown lawn with no hedge often falls within it. A plot with a hedgerow along one boundary usually does not, because five metres is a short length.

Householder applications are exempt, but a new dwelling is not a householder application however small the plot.

Where none of those applies, you need a habitat baseline surveyed by someone competent to identify habitats to the standard the metric requires, the metric calculation itself, and a Biodiversity Net Gain Assessment explaining the approach. The Environment Act 2021 regime expects a competent person to complete the statutory metric, so treat any AI-drafted document as the framework a competent person works within rather than as the assessment itself.

Drainage evidence for one plot

Councils increasingly refuse or hold minor applications on drainage, and on an infill plot the issue is usually that the existing garden absorbed rainwater and the new roof and driveway will not.

Answer three questions in a short drainage statement:

1. Where does surface water go, working down the hierarchy from infiltration to a watercourse to a surface water sewer, with a combined sewer as the last resort?
2. If infiltration is proposed, what does the ground actually do? A soakaway test to the standard method, or at minimum a trial pit record and the British Geological Survey mapping for the area.
3. Where does foul drainage connect, and has the sewerage undertaker confirmed the connection point?

On sites of less than one hectare outside flood zones 2 and 3, a full flood risk assessment is not usually required, but the surface water question still has to be answered. A statement of half a page with a soakaway calculation attached will clear it. An application silent on drainage will not.

Trees on and next to the plot

Infill plots are carved out of gardens, and gardens have trees. The question is whether any of them are protected and whether the construction footprint touches their root protection areas.

Check for a tree preservation order and for conservation area status, which brings a six-week notification requirement for works to trees over a certain size. Then commission a survey to BS 5837:2012 where any tree of reasonable size stands on or adjoining the plot. The survey categorises trees A to U, plots root protection areas, and feeds an arboricultural impact assessment and a tree protection plan.

Trees belonging to a neighbour matter as much as your own. A root protection area does not stop at the boundary, and a foundation design that encroaches into next door's mature oak will be conditioned or refused. The tree survey should be done before the footprint is fixed, not after, because moving a house by two metres on a drawing is free and redesigning foundations is not.

Access, visibility and parking

The highway authority looks at three things on a single dwelling: whether the access can achieve visibility splays appropriate to the road speed, whether a vehicle can enter and leave in forward gear where the road warrants it, and whether parking meets the local standard.

Supply a drawing showing the splays with dimensions, the surfacing for the first few metres from the carriageway, gate positions set back far enough that a car can pull off the road before opening them, and the turning area. Where the plot shares an access with the host dwelling, show both parking provisions.

Where the plot fronts a classified road or an access onto a fast rural road is proposed, expect a request for speed survey data. That is a small cost that removes an argument about assumed speeds.

Where heritage or flood risk adds a report

Two constraints change the pack materially.

In a conservation area or within the setting of a listed building, add a heritage statement assessing significance, then effect, then justification. Photographs from the viewpoints where the new dwelling would be seen alongside the heritage asset do more than paragraphs of description.

In flood zone 2 or 3, or on a site with surface water flood risk shown on the Environment Agency mapping, add a Flood Risk Assessment with finished floor levels, access and egress and, where the zone requires it, the sequential test. A single dwelling in flood zone 3 is a hard case, and the sequential test is where most of them fail.

Contamination is worth a thought where the plot was previously a workshop, filling station, orchard sprayed for decades, or made ground. A short desk study costs less than a condition requiring a full investigation before you can start.

Sequencing surveys against the design

The seasons decide the programme, not the design work.

Bat emergence surveys run from May to September where a building is being demolished or a roof altered. Great crested newt eDNA sampling runs from mid-April to the end of June. Botanical survey for a biodiversity baseline needs the growing season, and a February habitat survey will be challenged. Tree surveys can happen year-round but canopy assessment is better in leaf.

So the order that works is: check constraints and the local validation list in month one, commission ecology and trees as soon as the season allows, fix the footprint around the root protection areas and the drainage solution, then draw the scheme properly, then write the statements. Reversing that produces a beautiful design that has to move three metres.

If you are replacing an existing house rather than building on open land, the pack differs in several respects, and the reports needed to demolish and rebuild a single house sets those out.

Enter your postcode to see which reports your plot is likely to need. 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.