Planning constraints to check before buying a development site
Before buying a development site, check six critical planning constraints. Here is what each one means and how to check them fast.
Why planning constraints matter before you buy
Planning constraints are the non-negotiable rules that govern what can and cannot be built on a piece of land. A site either sits within the Green Belt or it does not. A building is either listed or it is not. These are factual designations with specific legal consequences for development.
Checking constraints is the very first thing you should do when evaluating a site -- before you instruct solicitors, before you engage architects, and certainly before you exchange contracts.
The six constraints every developer must check
Flood risk zones
The Environment Agency classifies land into flood zones. Zone 1 means low probability (less than 1 in 1,000 annual chance) -- you can build most things here. Zone 2 (medium probability) requires a Flood Risk Assessment and Sequential Test. Zone 3a (high probability) is difficult -- only water-compatible or essential infrastructure unless you pass both Sequential and Exception Tests. Zone 3b (functional floodplain) is usually a deal-breaker.
Conservation areas
Roughly 10,000 conservation areas exist across England. Development here must preserve or enhance the area's character. Demolition requires consent. Permitted development rights are restricted. Trees are automatically protected.
Green Belt
The NPPF establishes a very strong presumption against inappropriate development in the Green Belt. "Very special circumstances" must exist to justify approval. New buildings are generally inappropriate, with limited exceptions for infilling, redevelopment of previously developed land, and proportionate extensions.
Listed buildings
Grade I (2% of listings) covers buildings of exceptional interest. Grade II* (5.8%) covers particularly important buildings. Grade II (91.7%) covers buildings of special interest. Development within the setting of a listed building is a material planning consideration -- you do not need to be developing the listed building itself.
Areas of Outstanding Natural Beauty
AONBs (now National Landscapes) are designated for significant landscape value. The NPPF gives great weight to conserving landscape beauty. Major development is normally refused unless there are exceptional circumstances.
National Parks
National Parks carry the highest landscape protection. The National Park Authority is the planning authority, not the local district council. Even smaller schemes receive careful scrutiny for landscape impact.
The manual process
Checking all six manually means visiting multiple government websites: Environment Agency flood maps, local authority constraint maps, Historic England's database, Natural England's MAGIC Map. Each check takes 5-15 minutes. Across six constraints, you are looking at an hour or more per site.
MarketCode's planning-check skill runs all of these from one address: every designation and constraint graded by severity, the flood position and the nearby planning history.