Biodiversity net gain plans in Hillingdon

Which Hillingdon projects fall outside the rules

An extension, porch or loft conversion on an existing house is a householder application and exempt, as is anything built under permitted development. A new house on a site no bigger than 0.2 hectares is also exempt, provided no priority habitat is affected.

Hillingdon's Green Belt location matters here. A plot of that size beside open land can still hold priority habitat, such as traditional orchard or lowland meadow, and one such parcel removes the small-site exemption. We check the habitat mapping before telling you the exemption holds.

Smaller disturbances can be ignored altogether: under 25 square metres of habitat and 5 metres of hedgerow or similar linear habitat count as de minimis.

A practical test before you spend anything: walk the plot and photograph it as it is today, with dates. If the land is mown lawn, paving and a few shrubs, the baseline is low and the gain is easy to meet. If it is rough grass, scrub or old fruit trees, expect a bigger task, and do not clear it first, because clearing can be treated as lowering the baseline.

What we draw and calculate for a Hillingdon site

The plan starts with a baseline survey, each habitat parcel mapped with its area and condition. We then calculate the post-development value and draw the planting, green roofs, hedges and ponds that deliver the gain, so an officer can tie each unit of the metric to a feature on the sheet.

Plots near the Green Belt edge often suit on-site delivery, because there is room to keep a wildlife strip along the boundary instead of paying for off-site units. Our new build drawings carry the same landscape layout, so the plan and the planning set agree.

Whatever is delivered must be kept up. The gain is secured for at least 30 years, so we also write the management notes that explain who looks after each parcel.

Timing against the planning decision

Householder cases in Hillingdon are granted 90.2 per cent of the time, but minor applications, the category a new dwelling usually falls in, are granted 68.7 per cent of the time across 367 decisions. The gap shows why a new-home scheme needs its ecology tidy at submission.

The net gain condition is discharged before work starts, not at validation. We prepare the plan alongside the drawings so you are not waiting on a metric when the permission arrives. If a refusal is possible, see how our planning appeals work is run.

Householder decisions in the borough also run to 1,147 cases, so officers know the exemption well. They look harder at a scheme that claims it for something that is really a new dwelling, which is another reason we state the basis for any exemption on the form.

Price and how to start

There is no list price for this plan, because the work follows the number of habitat parcels and whether off-site units are needed. You get a fixed quote after a free constraints check.

Send the address and a sketch of what you plan to build. We will say if the condition applies, what survey it needs and what to avoid doing to the plot first. Wider drawings for the same site are covered under our planning drawings service.