Chris and Michele Jones knew exactly which direction to go when they decided to extend their house — upwards. The house in Bromley, Kent, in which they had lived since 1996, was flat roofed. An architect had built it nearly 40 years previously for his family and it incorporated a number of features that Chris and Michele liked.
In particular, there is a lot of timber inside, especially on the ground floor. “I call the style ‘Modernism with a soft edge’ — it is really a sort of Scandinavian version of European Modernism,” Chris, an architect, explains. “You still see quite a lot of it in houses built in the early 1960s. We wanted to keep this style and add to it in a manner that would be respectful of what was there already.”
The need to do something was made more urgent by the fact that the roof, which was covered with three layers of ’60s roofing felt, was ‘ponding’ with water on the surface and also leaking slightly in places. Chris and Michele carried out repairs but they knew the ultimate answer was to replace it. The best way of going about this was to add a complete storey to the house or, as Chris likes to call it, “put on a new lid”.
“As an architect I had worked on flat-roofed buildings and knew the membranes of today were far superior to those used in the ’50s and ’60s,” Chris says. “I had quite specific ideas about the sort of third storey I wanted, with the new walls set back, to create a roof overhang.”
The scheme would add about three metres to the roof, and as many other houses in the road had pitched roofs that were higher, Chris could not see why this shouldn’t be acceptable to local planners. “I deliberately drew up fairly abstract drawings for the application,” Chris says. “To my amazement there were no negative noises from the planning department — just a letter after a few weeks giving a straight approval. I think some supportive letters from our neighbours helped a lot. They appreciated what we were trying to do — to make something interesting out of a rather tired ’60s house. There were no written objections. I think we were helped by a model I made of the scheme, which I showed to interested parties.”
The only major hurdle came when the Building Control officer insisted on an alternative means of escape, because the extended house would incorporate a third floor. Chris and Michele solved this very neatly by installing a folding ladder, which from a distance can easily be mistaken for an aluminium drainpipe.
Apart from Chris and Michele, the key players in the build were Michele’s father, David Burchess, a structural engineer, and builder Nick Barber. “The two had worked together before, so Nick came to us with a known pedigree,” Chris says. “He has a carpentry background, which helped because the new structure is mainly timber and was nearly all ‘dry’ work. The only masonry involved was where we had to make some alterations to the dual skin of the house and build a low parapet extending upwards to enclose the external spaces.
The policy was to make the new storey as light as possible and to keep all the main roof loads on the existing outer walls. This meant constructing a threebay steel frame to support the roof. All that is visible is eight elegant round steel posts which do all the work of supporting the roof.
The entire structure is given over to Chris and Michele’s new en suite bedroom, with covered outside space on three sides. Apart from the lightness of the structure and the light that flows in through the ample glazing to the south, the other really distinctive feature of the new floor is the bathroom. This occupies the lower half of a four-and-a-half-metrehigh timber drum with a cedar-boarded exterior. It stands one-and-a-half metres above the roof — the reason being that the top half contains the water tank.
“I gained the idea of the drum from what was here before — a rectangular timber-clad structure housing the water tank,” Chris explains. “We decided to continue with this system rather than go for a direct pressure water system because we were not sure our old pipework would cope with a new system of this sort, and because Michele, a caterer, was at the time running her business from home and needed a reliable supply of water.”
The main structure of the new building has timber studding between the steel frame of the exterior walls. It is highly insulated, with an insulated render system applied to the studs and sheathing board, plus extra insulation placed inside the sandwich of the structure.
The roof is also of ‘warm roof’ construction, with the insulation above the plywood decking and beneath the single-ply roof membrane. Look at it from a distance and you will see that the roof is not actually flat, but rises to an almost indistinguishable ridge, with a very slight pitch on either side.
Inside, Chris has tried hard to replicate the original feel of the house by using a great deal of timber. This goes well with the lightweight nature of the new floor — and has allowed him to produce a second storey that is very much of the 21st century but also has echoes of the early 1960s ground floor.
A good example of this is the new staircase to the second floor. It has treads and risers of cherry wood – echoing some of the ground floor features – but the balustrade is formed by floor-to-ceiling glass sheets. Below this, the original house is unaltered apart from the changes to the former master bedroom, now occupied by daughter Lara.
Chris and Michele lived in the house throughout the 11-month build. “It was very frustrating at times because it went on for so long. I was running my catering business from home at the time, and juggling three vans around in the drive with builders’ vehicles coming and going was not easy,” says Michele. “Once it was all finished I moved the business to some new premises two miles away. Nevertheless we managed to sleep largely unscathed in our existing bedroom. This was because we had a big sheet over the roof on a scaffold for eight months.”
All is not finished. The next major task will be to remove the conservatory at the rear and replace it with a single storey permanent extension. “The conservatory was added in 1994 by the people who bought the house from the original owner,” says Chris. “I don’t like it: it has been a constant source of aggravation.
“This is a house you either love or hate. I believe we have improved it. Before it was quite horizontal in feel — a little squat. By adding the ‘lid’ we have made it look better from the outside by creating the roof overhang and setting back the new walls. By creating external spaces in this way – and also adding the drum – we have created a more interesting house.”
Adding an extra storey is not the most conventional way of gaining extra living space, but if the plot is on the small side it is often the only way of doing so — although it is more expensive than extending outwards. The key things to consider are that the design must really look like it belongs, and preferably enhance the exterior, as it does in this case. Also, the planners may insist that it does not exceed the roofline of neighbouring houses. Ensure you plan the new rooms according to the views — the bedrooms and the living areas should receive the best views. Also bear in mind that extending upwards will require the roof to be removed while the work is completed. You will be adding extra weight onto the existing house and you need to be sure that it is able to handle it — a structural engineer will advise.