51 Thorndon Hall, Ingrave (replacement sash windows, listed building consent)

Decision

dismissed, 2 October 2026

Decided by

Planning Inspector: Timothy King

Authority

Brentwood (East of England)

Appeal reference

6005177

Application reference

25/00822/LBC

Procedure

written representations

Development

Replacement of three single-glazed timber sash windows with slimline double-glazed units in a first-floor flat

Site context

listed building setting, conservation area

Green Belt

No

Framework applied

August 2026 NPPF

Determinative policies

HE6(4), HE4(2)

Main issues

significance of the listed building; conservation area

Summary

Listed building consent was refused for replacing three decayed single-glazed sashes with slimline double glazing in a flat at Grade I Thorndon Hall. The inspector gave substantial weight under CC2(2) to improving energy efficiency, but there was no specialist evidence that the windows were beyond repair and no account of alternatives such as secondary glazing. The loss of fabric harmed the building's significance without clear justification, and the harm was not outweighed by public benefits. Dismissed.

Issues and findings

• Transition. No switch paragraph. The letter applies HE4, HE6 and CC2(2) by their 2026 codes.
• Listed building: HARM. "I conclude that the proposed works cause harm to the significance of this listed building" (DL ¶18). The degree of harm is not graded.
• Evidence gap. "there is no report provided by any timber specialist to confirm that the existing windows have been personally examined and neither repair nor splicing can be reasonably considered possible or viable" (DL ¶15).
• Less harmful alternative. "research by Historic England has shown that the use of secondary glazing with low emissivity coating can significantly reduce heat loss" (DL ¶23).
• Conservation area: PRESERVED. "any discernible visible change would be so localised as to have little or no appreciable effect on the character of the conservation area" (DL ¶20).
• HE6(3) and HE4(2). "any resultant harm will be a matter of considerable importance and weight and, as indicated in policy HE4 thereto, any such harm should have a clear and convincing justification" (DL ¶28).
• Energy efficiency, CC2(2): substantial weight. "In accordance with policy CC2(2) of the Framework I give substantial weight to the benefits of improving the energy efficiency of existing buildings." (DL ¶30).
• Reuse benefit not available. "If the listed building was vacant or under-occupied, and the proposed works were widespread to assist with its beneficial re-use then this would represent a public benefit. However, that is not the case here." (DL ¶31).

Planning balance

HE6(4): harm of considerable importance and weight to a Grade I building against an energy-efficiency benefit given substantial weight in principle but not shown to require these works. "no clear justification has been made for the extent of the works proposed here. This is not outweighed by any public benefits." (DL ¶33).

What made the difference

The absence of a specialist's report. The photographs showed frames needing considerable repair, but nothing showed that repair or splicing was not possible, or why secondary glazing would not do. With a timber survey, detailed specifications and an options appraisal the proposal would have been complete; the inspector called it "an incomplete proposal" (DL ¶32).

Transferable points

• CC2(2) substantial weight for energy efficiency does not decide a listed building case: the benefit must be shown to need the harmful works (DL ¶30, ¶32-33).
• Wholesale window replacement in a listed building needs a specialist's report that repair is not possible or viable (DL ¶15).
• Secondary glazing is treated as a less harmful route to the same benefit (DL ¶23).
• Windows installed in a 1980s conversion still counted as fabric whose loss harms a Grade I building (DL ¶10-11, ¶32-33).
• Consistency of fenestration across a large listed building is a legitimate concern where flats are altered one at a time (DL ¶17).
• Three windows did not harm the conservation area as a whole, so the effect on a listed building and on a conservation area must be assessed separately (DL ¶20).

Policy findings

Policy codes are those of the National Planning Policy Framework (August 2026) unless a development plan is named.

Key facts

• Thorndon Hall is a Grade I listed 18th century country house converted to 84 flats in the 1980s; the existing sashes are said to date from that conversion (DL 2, 10)
• Three rear-facing first-floor windows with timber frames in poor repair (DL 3-4, 15)
• No timber specialist's report that repair or splicing is not possible or viable; Heritage Statement's claim of a very similar appearance unsubstantiated (DL 15-16)
• Historic England guidance cited, repair before replacement, accurate copies if beyond repair, and secondary glazing as an alternative that leaves the window unaltered (DL 11-14, 23-24)
• Council's concern for a consistent fenestration typology across the building accepted as understandable (DL 17)
• Comparators distinguished, No 37 (modern rooftop flat not visible from the ground) and Ledston Hall (DL 25-26)
• Reuse of a vacant listed building would be a public benefit, but the building is occupied (DL 31)
• Site visit 14 July 2026; no switch paragraph; 2026 policy codes used; no development plan policy cited
• Letter slips, "Paragraph HE6" (DL 28) and rooms kept cool "during the winter months" (DL 21)

Sources

• Appeal on the Planning Inspectorate appeals service
• Decision letter (Planning Inspectorate)

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.