Can I extend this house?
Can I extend this house — and what will the ground and the trees make me build?
A free verdict on your householder permitted-development rights, read from the designations at your point. Three limits up front: it is England only, it covers existing houses, not flats, and it cannot see rights removed by a planning condition on the original permission, because no national dataset records those.
Limited rights — Bath conservation area and the City of Bath World Heritage Site at the point, in Flood Zone 3; medium shrink–swell ground with a tree inside its influence zone puts footings in the 2.0–2.5 m band, 57 % of the garden gets six hours of June sun against 3 % in December, and all 5 householder applications within 100 m in three years were approved.
Read the full sample report →What the £19 report covers
Consent needed, limited rights, full rights, or cannot confirm — with the designation that decides it quoted.
Protected trees, listed buildings, flood zones and bands, main rivers within 8 m, recorded mine entries, radon — each with what it changes for your build.
BGS 1:50,000 geology at the point, the shrink–swell class, the nearest tall tree from LIDAR, and the NHBC foundation-depth band an engineer will start from.
Distances to the neighbouring walls from OpenStreetMap footprints: within 3 m or 6 m triggers a Party Wall Act notice for foundations.
Direct sun hours on every square metre of the garden on 21 June, 20 March and 21 December, with the sunniest 2 m².
Every householder application within 100 m in the last three years, what was approved and what was refused.
Questions
Can I extend my house without planning permission?
In England most houses have householder permitted-development rights: a single-storey rear extension up to 4 m (detached) or 3 m (other houses), or 8 m / 6 m under the larger-home prior-approval route, up to 4 m high, with eaves no more than 3 m within 2 m of a boundary and no more than half the curtilage covered. Those rights are cut back on Article 2(3) land (conservation areas, national parks, AONBs, World Heritage Sites) and removed by Article 4 directions; listed buildings need listed building consent for everything. Flats have no householder rights at all. The free check reads the designations at your point from planning.data.gov.uk and tells you which band you are in.
Why does the report say the council has not published its Article 4 directions?
Councils upload Article 4 directions to planning.data.gov.uk themselves and many have not. "Nothing found" from a council that has uploaded nothing is not an all-clear, so the report checks whether the council has published any Article 4 rows at all before giving a full-rights verdict. If it has not, the verdict is "cannot confirm" and the honest next step is the council’s own constraint map.
How deep will my extension foundations need to be?
An engineer decides, but the band is predictable from two things: how much the ground shrinks and swells (clay soils such as London Clay, Gault and Oxford Clay are high; sands, gravels and chalk are low) and how close a tall tree is. NHBC Chapter 4.2 turns those into a minimum depth from about 0.75 m on low-shrinkage ground with no trees to over 2.5 m on high-shrinkage clay with a mature tree within a fifth of its height. The report reads the BGS 1:50,000 geology at your point and measures the nearest tall tree from Environment Agency LIDAR to give you that band.
What does the sun map show?
Direct sun hours on each square metre of the garden on 21 June, 20 March and 21 December, computed by tracing the sun’s path across the day against the 1 m LIDAR surface model, which carries every roof, wall and tree crown around the house. It is clear-sky, direct sun only. Use it to decide where a rear extension would put the patio into shade, and where the sunniest corner is worth keeping.
Which houses can the report not cover?
The verdict uses planning.data.gov.uk, which covers England only; Wales, Scotland and Northern Ireland are shown as not covered rather than guessed. Flats and maisonettes have no householder rights. Some estates had rights removed by a condition on the original permission, which no national dataset records, so the council’s decision notice is the only check for that. Where the LIDAR composite has a gap, the tree and sun sections say so.
Sources: planning.data.gov.uk (OGL v3); BGS 1:50,000 geology and GeoSure (contains British Geological Survey materials © UKRI); Environment Agency 1 m LIDAR composites, flood zones and main rivers (OGL v3); Defra NaFRA2 bands; HM Land Registry INSPIRE index polygons (© Crown copyright); OpenStreetMap (ODbL); PlanIt; Mining Remediation Authority; UKHSA radon. Permitted development is a legal test — apply for a lawful development certificate before building under it. How we check.
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