Hillingdon Council granted planning permission for the householder application at 149 Herlwyn Avenue (Ref: 19188/APP/2026/820) today. The approved retrospective application permits the conversion of the roof from a hip to a gable end, the inclusion of a rear dormer to create habitable roof space, and the erection of a single-storey rear extension.
The planning officer’s report concluded that the development is acceptable regarding design and residential amenity, noting that the rear extension is a 3-metre deep infill and the roof alterations are similar to others on the street.
It’s not an HMO!
In response to public consultation comments raising concerns about a potential multi-occupancy use, the report explicitly clarified that this application is not for a House in Multiple Occupation (HMO).
The Council also highlighted that an Article 4 Direction has covered the entire borough since 11th December 2025. This direction removes Permitted Development rights for changing single-family dwellinghouses (Use Class C3) into small HMOs (Use Class C4), meaning any such future conversion would legally require planning permission and could face enforcement action if undertaken without it.
- Read the full Officers Report on the Hillingdon website
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