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15b Herne Hill Road

Renovation of flat in Victorian terrace house, creating new living area within restructured roof space using unusual and reclaimed materials, and retrofit of substantial insulation.


Colin MacInnes



15b Herne Hill Road SE24 0AU

Sat/Sun 12noon-5pm.


Denmark Hill, Loughborough Junction

35, 45, 345, P4, P5

  • Green features
  • Refreshments available

15b HERNE HILL ROAD BackgroundThis is a renovation which has been carried out gradually between 2011 and 2015. It is a self-build project with all design and construction work being carried out by the owner. The flat occupies the top two floors of what was originally a four-storey Victorian terrace house. Before work started, the kitchen and living room were on the lower floor, with two low-ceilinged bedrooms on the upper floor within the mansard roof.Upper floorThe bulk of the work has been in re-configuring the upper floor. A new timber roof structure has been inserted from the inside, allowing the dividing walls and old ceiling to be removed to open it up into one space containing the new kitchen and living areas, as well as a semi-enclosed work area behind a screen of translucent polycarbonate wall panels. A single large rooflight has also been added. The kitchen has been constructed using zinc sheet formed onto plywood carcasses. The timber boarding running up the walls and onto the ceiling was created by sawing and sanding down the timbers which were taken out of the old roof structure. On the long side wall is a screen made up from wooden laths suspended within a steel wire framework. These laths were recovered from some of the old interior lath-and-plaster walls removed during the project.Lower floorThe larger room at the front, which was previously the living room, is now the main bedroom. The wall surfaces are made from painted, recycled pallet boards. Window shutters are built in to match. The smaller room to the rear, which was previously the kitchen, is now a second bedroom, finished in a similar style.Insulation and energy efficiencyOne of the main aims of this project has been to try and improve energy efficiency by adding fairly substantial insulation, which by necessity has been applied internally rather than externally. There are numerous technical and practical difficulties involved in insulating an existing (and aging) building which have had to be tackled here. Behind all of the finished wall surfaces you see, there is between 100mm and 200mm (4 to 8 inches) thickness of polystyrene or polyurethane insulation. With substantial insulation comes a need for a high level of airtightness, and an attempt has been made to achieve this without use of the conventional (and arguably fragile) method of relying on thin membranes and adhesive tapes. Instead, OSB sheathing (a type of particle board) has been used to create the airtight layer. Within the roof area the OSB boarding also plays a structural role. At this stage effort and resources have been concentrated on insulation, as this is a measure that has potential to have a big effect on energy use, and can’t be added at a later point without major disruption. So you won’t see evidence of any complicated or expensive energy-saving technology beyond a small but efficient combi boiler. There is an intention to add a simple heat-recovery ventilation system in due course and there is potential for solar water heating to be installed in the future if funds allow.Questions and more detail…Please do ask if you are interested in more detail about the methods used to add the insulation, or have any questions about anything else you see. I can also tell you a bit about the data-logging monitors which are installed within the walls to track changes in temperature, moisture and humidity.Designed & built by Colin MacInnesSeptember 2015