- Decision
- dismissed, 23 September 2026
- Decided by
- Planning Inspector: M Cryan
- Authority
- Haringey (London)
- Appeal reference
- 6008944
- Application reference
- HGY/2025/3167
- Procedure
- written representations
- Development
- Mansard extension and conversion of upper-floor 3-bed maisonette to three 1-bed flats
- Homes
- 2
- Site context
- inside settlement, conservation area
- Green Belt
- No
- Framework applied
- August 2026 NPPF
- Determinative policies
- HE6, HE7, S4(1), L2(1)(d)(i), DP3(1)
- Development plan policies
- Haringey Strategic Policies 2017 SP11, Development Management DPD 2017 DM1, DM9, DM12, London Plan 2021 D6, HC1
- Main issues
- conservation area and non-designated heritage asset
Summary
A mansard on a locally listed early-19th-century building in the Bruce Grove Conservation Area, turning a maisonette into three flats. It was dismissed on a non-determination appeal. The inspector found moderate harm to the CA, through the loss of the building's authenticity as a non-designated heritage asset. A net gain of two flats did not outweigh it. L2's airspace support failed its own street-scene limb (L2(1)(d)(i)), so under S4 the benefits were substantially outweighed.
Issues and findings
- NDHA harm feeding CA harm. "While Policy HE7 ... says that harm to the significance of an NDHA 'should be weighed against the benefits ... and a balanced judgement made', here the harm would undermine the positive contribution the appeal property makes to the significance of the BGCA as a designated heritage asset" (DL ¶13).
- Design. "the building taking on a disproportionately tall and narrow appearance ... The dormers would be set forward of the mansard roof slope which would give them a bulky and dominant appearance" (DL ¶10).
- HE6. The harm was moderate, "though Policy HE6 ... recognises that any harm will be a matter of considerable importance and weight". The net gain of two dwellings, "even a modest uplift in housing supply is an appreciable public benefit", did not outweigh it (DL ¶13-14).
- L2 airspace. L2(1)(d) gives substantial weight to using airspace, but "Policy L2 goes on to say (at paragraph 1.d.i.) that such development should be consistent with the overall street scene" (DL ¶18-19).
Planning balance
This was the S4 balance: "Taken together, I find the benefits of the proposal would be substantially outweighed by the adverse effects" (DL ¶20).
What made the difference
The rarity of mansards in this CA, and the building's prominence at a junction. Where a CA appraisal restricts mansards, the Framework's airspace support cannot override it. This decision is a near twin of PINS-6011521 (Westminster).
Transferable points
- Harm to a locally listed building that contributes to a CA is weighed as CA harm under HE6, not just under the NDHA balance in HE7 (DL ¶13).
- L2(1)(d)(i) is an internal limit on airspace support: no street-scene consistency, no substantial weight (DL ¶18-19).
- A net gain of two flats is an "appreciable" benefit but does not outweigh moderate CA harm (DL ¶14).
Policy findings
Policy codes are those of the National Planning Policy Framework (August 2026) unless a development plan is named.
| Policy | Finding | Weight | Note |
|---|---|---|---|
| HE6 | harm | considerable | moderate less-than-substantial harm to Bruce Grove CA; net gain of two flats does not outweigh (DL 13-14) |
| HE7 | harm | loss of original roof form and authenticity of locally listed building; disproportionately tall and narrow (DL 10-13) | |
| L2(1)(d)(i) | fail | airspace development not consistent with the street scene (DL 18-19) | |
| S4(1) | fail | benefits substantially outweighed (DL 20) |
Key facts
- CA appraisal says mansards are acceptable only if original or established and behind a parapet; only a handful exist in the CA (DL 8-9)
- Prominent site opposite the Bruce Grove junction and visible from trains (DL 11)
- Non-determination appeal; the letter does not say whether the parties were consulted on the new Framework (DL 2-3)
Related decisions
Sources
This note is one of the decisions behind the NPPF 2026 Navigator, which shows how each Framework test has been applied across all the decisions in the database. Also available as Markdown.