What is a consent gap in conveyancing?

A consent gap occurs when physical changes have been made to a property — such as an extension, loft conversion, or change of heating system — without the corresponding planning permission, building regulations approval, or listed building consent. In conveyancing, identifying consent gaps is critical because undisclosed alterations can affect the property's value, insurability, and the buyer's ability to obtain a mortgage.

Common types of consent gap

Alteration	Required consent	Risk if missing
Rear or side extension	Planning permission + building regs	Enforcement notice, mortgage refusal
Loft conversion	Building regulations (fire, structure)	Insurance void, safety risk
Removed chimney breast	Building regulations (structural)	Structural failure risk
Replacement windows	FENSA certificate or building regs	Sale delayed, indemnity needed
Change of use	Planning permission	Enforcement, mortgage issue

How HouseData PRISM detects consent gaps

HouseData's PRISM (Property Risk Intelligence for Solicitors & Mortgage-readiness) product detects consent gaps automatically by cross-referencing:

• EPC time-series data — changes in floor area, number of rooms, heating system type, or insulation between successive EPC assessments
• Planning records — whether corresponding planning applications or building control sign-offs exist for detected changes
• Heritage registers — whether the property is listed or in a conservation area (which requires additional consents)

The result is a Consent Gap Score that conveyancers can use to quickly identify properties that need further investigation, reducing professional liability exposure and speeding up the conveyancing process.

Learn more about PRISM or email hello@housedata.uk for access.

Source: HouseData PRISM methodology using DLUHC EPC Register, Planning Portal, and local authority data. Read our full methodology.