New mansard roof and minor internal and external changes at the rear, including the removal of existing windows and replacing the rear bathroom window with a door

Appeal Decision Site visit made on 14 February 2018 by John Dowsett MA DipURP DipUD MRTPI an Inspector appointed by the Secretary of State Decision date: 15th March 2018 Appeal Ref: APP/N5660/D/17/3186157 131 Heath Road, London SW8 3BB  The appeal is made under section 78 of the Town and Country Planning Act 1990 against a refusal to grant planning permission.  The appeal is made by Valerie Dickson against the decision of the Council of the London Borough of Lambeth.  The application Ref: 17/03406/FUL, dated 13 July 2017, was refused by notice dated 6 September 2017.  The development proposed is a new mansard roof and minor internal and external changes at the rear, including the removal of existing windows and replacing the rear bathroom window with a door. Decision 1. The appeal is dismissed. Main Issue 2. The main issue in this appeal is the effect of the proposed development on the character and appearance of the existing building and the surrounding area. Reasons 3. The appeal building is part of a terrace of older houses with more recent housing development to the south and west. Numbers 133 to 139 Heath Road to the east of the appeal building are two storey houses with a semi-basement and are taller than the remainder of the terrace, including the appeal building, which are two storey but do not have basements. The terrace is of traditional construction with shallow pitched, or butterfly, roofs concealed behind a parapet. The south side of Robertson Street to the north is a longer terrace of similar houses with an identical roof configuration. 4. Policy Q5 of the Lambeth Local Plan 2015 (the Local Plan) expects new development to respond positively to the local context and historic character, and to maintain local distinctiveness. Local Plan Policy Q11 relates specifically to extensions to houses and seeks to ensure that, among other matters, the design of the extension retains the architectural integrity of the original building and its group, and remains subordinate to the main house. In relation to mansard roofs Policy Q11 also requires that these replicate locally distinct forms, materials and detailing. More detailed guidance on the construction of mansard roof extensions is set out in the Lambeth Building Alterations and Extensions Supplementary Planning Document 2015 (the SPD) which is to be read alongside these more general policies. Appeal Decision APP/N5660/D/17/3186157 2 5. It is common ground that the proposed mansard roof meets the majority of the relevant requirements of Paragraph 4.25 the SPD in terms of the roof pitches of the mansard and consequential alterations, including raising the height of the party wall and the chimney stacks. The Council state that the appeal proposal does not comply with the SPD as the dormer windows in the proposed mansard do not align with the windows in the elevation below. 6. Paragraph 4.23 of the SPD refers specifically to proposals for mansard roof additions to properties which have a butterfly roof, referred to as a London roof in the SPD, such as the appeal building. This states that the replacement of a butterfly roof with a traditional full mansard will only be permitted if all of the design criteria in Paragraph 4.25 of the SPD are met. The submitted drawings show that the proposed dormers are offset from the windows below on the lower floors. Criterion f of Paragraph 4.25 requires that windows in mansards should match those below. 7. Whilst I accept that neither the SPD nor the Local Plan policies state that windows should be aligned, in buildings of the age of the appeal building it is usual for the window openings on each floor to be directly above those on the floor below, and this is the case with all the buildings within this terrace. This establishes a regular rhythm and pattern of windows throughout the terrace and is intrinsic to its basic character. The offset windows in the mansard would break this rhythm and would appear as a jarring feature. In this context, the windows in the proposed mansard would not match those below. This would be exacerbated by the mansard being the only one present in the street at this time. 8. The lower floor windows of the appeal building are of a two over two pane, sliding sash design and the proposed dormers are shown on the submitted drawings as having only a single pane window that would not reflect this glazing configuration. I saw when I visited the site that on a number of mansard roofs which have been constructed on properties in Robertson Street the dormer windows align with the windows on the floor below. In addition, the windows in these dormers are separated by a single horizontal glazing bar which reflects the pattern of the glazing in the main windows of the houses but translated to a smaller window. 9. The fact that the proposed dormers would be offset from the windows below and would not reflect the glazing pattern of the windows of the original house does not, to my mind, constitute either good design or matching the windows below and, consequently, would not comply with the requirements of the SPD. For the same reasons the proposal would also compromise the architectural integrity of the house and would not comply with the relevant requirements of Policy Q11 of the Local Plan. This would be harmful to the appearance of the building and the surrounding area. The National Planning Policy Framework also expects new development to be of a high standard of design and states that permission should be refused for development of poor design that fails to take the opportunities for improving the character and quality of an area. 10. Although there are no other roof alterations within the terrace and it retains an unbroken line of butterfly roofs, the wording of the SPD at Paragraphs 4.23 and 4.25 clearly contemplates that the replacement of a butterfly roof with a traditional mansard roof that meets the design criteria in the SPD can be supported if the building is not a heritage asset. The appeal building is not Appeal Decision APP/N5660/D/17/3186157 3 Listed, nor is it within a conservation area. This is also evidenced by the addition of mansard roofs to the properties on the south side of Robertson Street which, similarly, have butterfly roofs concealed behind a front parapet. 11. Heath Road has a mixed architectural character with mid Twentieth Century two storey housing to the south side and a modern Kingdom Hall adjoining the terrace that contains the appeal building. Whilst the proposed mansard roof would rise above the parapet at the front of the terrace, the proposed dormer windows are set behind this and due to the higher level of the adjoining properties at 133 to 139 Heath Road there would be some mitigation of the visual effect of the increased height. 12. Whilst the proposed mansard would add to the height of the appeal building, its dimensions have, in part, been determined by the requirements of the SPD. Due to the form of the mansard roof, set behind the front parapet and with a 30 degree pitch on the upper section, from street level its perceived height would be reduced. During my site visit I observed that similar mansard roofs on the houses in Robertson Street, which are of an essentially similar scale to the appeal building, did not appear overly dominant or out of proportion with their host building. 13. I also saw when I visited the site that the properties at the junction of Heath Road and Silverthorne Road, which are of a contemporary age to the appeal building, have been extended by way of a mansard roof with front facing dormer windows. 14. Within this context and given that the proposal complies with some of the criteria in the SPD with regard to adding a mansard roof to a property of this design, I do not consider that the addition of a mansard roof would either compromise the roofscape of the terrace and surrounding area, or appear as an incongruous or disproportionately large addition to the house. However, this does not outweigh the other harm that I have found in respect of the design of the dormer windows. 15. My attention has been drawn to a previous appeal decision in respect of a proposed mansard roof extension at number 123 Heath Road1. I do not have the full details of the case before me and so cannot be certain that it is directly analogous to the appeal proposal. I also note that this decision was made in 2010 and, consequently, pre-dates the guidance in the SPD. I further note that the Council have subsequently refused planning permission for another planning application at the appeal building for a proposal with an essentially similar description to the appeal before me. However, I have determined this appeal on its own merits. 16. I note that the Council have not raised any concern in respect of the proposed replacement of a rear ground floor window with a door. This is a very minor alteration to the property and from what I have read, and from what I saw when visited the site, I have no reason to reach a different conclusion in respect of this. 17. The SPD allows for the replacement of a butterfly roof with a mansard roof in certain circumstances. However, this is subject to meeting all of a strict set of criteria in respect of its detailed design in order to ensure that the mansard 1 APP/N5660/A/09/2108953 Appeal Decision APP/N5660/D/17/3186157 4 roof reflects the traditional design of mansard roofs in the borough and does not cause harm to the appearance of the host building or compromise its architectural integrity. I have found that the appeal proposal does not meet all of the relevant criteria and that as a result of its detailed design would be harmful to the appearance of the appeal building and the street scene. Although I have found that the appeal proposal would neither compromise the roofscape formed by the terrace containing the appeal building and those in the surrounding area, nor would it appear as an incongruous or disproportionately large addition to the house, neither of these points outweigh the other harm that I have found. 18. I therefore conclude that the proposed development would cause harm to the character and appearance of the area. It would not comply with the relevant requirements of Policies Q5 and Q11 of the Lambeth Local Plan 2015 and the guidance on the SPD. Other matters 19. Although the proposal would increase in the overall height of the appeal building this would not be so substantial in relation to the height of the existing building and the taller houses at 133-139 Heath Road that it would appear unduly overbearing to the occupiers of houses on Robertson Street. Whilst it may alter the amount of daylight received by these and cast a slightly longer shadow at certain times of the year, this would not, of itself, be grounds to refuse planning permission in this case. 20. The proposed rear dormers would face toward the rear elevations of terrace of houses on the south side of Robertson Street. However, these windows would serve a bathroom and provide light to the proposed new stairwell and landing area within the mansard roof. Due to the proximity of the two terraces there will currently be a degree of mutual overlooking and as a result of its internal configuration the appeal proposal would not exacerbate this. I also note that the Council have not raised any objections to the proposal on these grounds. 21. This notwithstanding, neither of these points leads me to a different conclusion on the main issue. Conclusion 22. For the above reasons and having regard to all other relevant matters raised, I therefore conclude that the appeal should be dismissed. John Dowsett INSPECTOR