Developers could find it more difficult to get permission to alter property if it is within Jersey's the new coastal park.
Rules governing the protection of the countryside have come into force after being approved by the States of Jersey.
Planning applications for projects inside the park would have to satisfy stricter criteria than before.
The first applications under the rules for the new coastal park are being considered by the planning authorities.
One of the properties developers hope to change is the Cheval Roc Hotel at St John.
There are plans to convert the existing hotel on the north coast into 22 flats with parking.
Another is an application by the Jersey Scouting Association for a shed at its centre at Les Mielles in St Ouen's Bay.
Application for development in the park made before it was set up by the States will be judged under the new rules.
The new coastal national park includes Wolf's Caves, Mourier Valley and Gorey Common.