Site and Constraint Due Diligence

Before relying on an ADU rule, make sure it applies to the right parcel and the right authority. An address pin, map layer, or property listing is a starting point; it is not a parcel determination or approval.

Start with the property and its authorities

Match the civic address to a parcel identifier and legal description, then identify the municipal, county, regional, provincial or state, national, and specialist authorities that answer the questions for that site. Different questions can have different decision-makers. Keep public planning rules separate from title, lender, association, and insurance documents.

Choose the check you need

Parcel, planning, and property records

• Identify the parcel, jurisdiction, and governing authority
• Find the zoning, plan, and overlay maps that apply
• Review title, easement, covenant, HOA, strata, and lender documents
• Check an England Article 4 direction
• Check Ontario’s municipal heritage register
• Check airport noise, airspace, and compatibility controls
• Identify the land-status and title-record authority

Water, coastal, and ground conditions

• Check flood, conservation, wetland, and hazard constraints
• Understand U.S. seismic-hazard maps and site-study limits
• Check New York freshwater wetland rules and request a DEC determination
• Screen a U.S. pipeline map before ADU excavation
• Check an England groundwater source-protection zone
• Check England flood-risk activity permit triggers
• Compare FEMA flood-map amendment options
• Check coal-mining risks in England, Scotland, or Wales
• Use Wales’ Flood Map for Planning
• Read Great Britain ground-stability maps
• Check California seismic zones before an ADU permit
• Move from a wetland map to a site determination and permit check
• Confirm a coastal, shoreland, or dune boundary
• Read ground-stability and landslide maps
• Check mine and legacy-well records before ground work
• Choose the right wildfire or postfire map
• Check a drinking-water protection area
• Check river, fish-habitat, and navigation review

Nature, heritage, and land-use controls

• Check heritage, listed-building, agricultural, and rural designations
• Check Canada’s critical-habitat map for an ADU site
• Check England Local Wildlife and Local Geological Site records
• Use USFWS IPaC for a U.S. species and habitat review
• Search contaminated-site records before planning an ADU
• Check UK statutory nature-site consent and species review
• Check England biodiversity net gain requirements and exemptions
• Check tree, woodland, and ravine controls
• Check agricultural reserves and rural designations
• Screen archaeology before ground disturbance
• Check UK scheduled-monument consent before work
• Use historical aerial photos as site-history leads

Before treating a result as decisive

Resolve conflicting parcel or authority records with the responsible office. Ask the relevant specialist or authority to confirm site-specific boundaries, designations, permits, or studies. A screen can identify the next check; it cannot establish that a particular property is buildable.