Jon Martin explains how he beat the odds with his extraordinary self-build tree house.
Interview with Jon Martin
Plumber Jon Martin and ceramicist Noreen Jaafar sold their high-maintenance Edwardian house to fulfil their dream of building their own home: an architecturally innovative Passivhaus that preserves the ecology of its urban plot.
Local knowledge helped Jon find an urban plot
Jon has always liked living in the town centre. He wanted to keep his fuel and energy costs and carbon footprint to a minimum. Urban plots are usually hard to come by but they managed to find one within nine months.
Once the large, formally planted garden of a bank manager, the plot was sold off by the Royal Bank of Scotland. Although considered an eyesore locally, the plot had 28 listed trees and a rich ecology, and various planning applications had been turned down.
Jon explained to the neighbours and council that he wanted to preserve what was there, not just “come in and butcher the area”. As a local, he thinks he may have been more readily trusted, saying, “I don’t think it had any sway but I didn’t get the resistance that I think somebody from outside might.”
The need for surveys and outstanding design increased cost
Jon and Noreen knew that gaining planning permission rested on their design adding outstanding architectural value to the surrounding area. Outline drawings cost a fair amount and an outstanding architect costs even more.
In addition, they needed to reassure the planners that existing ecology, arboriculture and even archaeology could be protected. There was abundant wildlife, including bats, badgers and slow worms. Jon says, “The only thing we don’t have is a great crested newt!” Specialists were needed to establish what was present and prove it could be preserved.
Buying without planning permission was a big risk
Although the house hasn’t been valued, Jon believes that the plot economics have worked out. However, he probably wouldn’t take such a risk again, saying, “We bought it without planning permission, actually having been told by the local Council we wouldn’t get planning permission.”
The plot cost £85,000 and its restrictions meant spending nearly £20,000 on surveys, meaning that the couple had borrowed £105,000 before getting planning permission. Considering their limited budget, Jon says, “It was either a very reasonably priced building plot or an incredibly expensive garden!”
Local support and detailed designs helped their appeal
Despite having unequivocal support from the neighbouring church and the Parish Council, the planning application was turned down. The only option was to go to appeal at the district Council. Jon went armed with a scale model showing every tree.
The appeal went through unanimously with the application cited as an exemplar of how to enhance a town centre. They have also been given a Campaign for the Protection of Rural England award. Jon says it is rare for a house to be recognised like this but with no concrete used throughout the build, it actually “treads very lightly”.
The design was challenging and contractors got cold feet
Finding the right professionals wasn’t straightforward. The structural engineer needed to work with a design delicately raising cantilevered sections into the air on slender legs, surrounded by trees. Planning how the 16 piles would miss tree roots took trial and error, digging small excavation holes and where roots were found, repositioning the pile and recalculating.
Unfortunately the first contractor they gave a deposit to went bankrupt. Moreover, Jon says that some contractors were put off by the project appearing on Grand Designs. A second contractor tendered for the contract but then got nervous and wanted to raise their price. About three years in, with only a few screw piles in the ground, Jon realised he had to take over as the main contractor.
Building a Passivhaus provided a standard to meet
The Passivhaus standard dictated levels for air quality, MVHR noise, duct size, energy use and temperature range. Jon says the cost of an energy consultant paid off in comfort, adding, “On a sunny day, it really does heat itself, it’s incredibly pleasant to live in.”
The Passivhaus ‘form factor’ determined how other aspects of design had to offset the shape of the building. Jon and Noreen’s house has quite a large surface area compared to volume and Jon says, “Everything has to be proportionally better to come in under the Passivhaus benchmark.”
Innovations in the structure and insulation benefitted the house
The house is free from thermal bridges, achieved by a “twin skin” containing 400mm of insulation. Using open-celled spray foam insulation improved airtightness and reduced off-gassing. Jon says it is nearly impossible to get the airtightness required for a Passivhaus using slabs of insulation. With spray foam and a lot of design and taping he achieved an exceptional airtightness.
The open-celled structure of the foam meant that off-gassing finished within two days whereas Jon says formaldehyde can come out of conventional slabs of insulation for decades. Although more of the open-celled material is needed, it breathes and is airtight and so he says it is hard to beat.
The house was 90% built by two people in 18 months
Jon thinks it took about 18 months of building for him and another man, with occasional help from a plasterer, an electrician and one additional man. Jon’s huge DIY effort included plumbing, putting the roof on, hauling and cutting all the timber and putting up the floors, walls and tonnes of steel.
Although the house wasn’t completely finished when they moved in, another six months saw the bedrooms and stud walls finished off.
Jon’s tips to keep it simple and love your build
Jon admits that he actually hated the build process at times. They even fell ill during the difficult planning process. “Unfortunately it really does rip your soul out,” he says. Now that he is settled into the building, however, he absolutely loves it.
House building is challenging and Jon would try to enjoy it more if he did it again. To achieve this, and come in on budget, his advice is to simplify:
- Choose a simple design
- Invest where it pays dividends: the fabric of the building, the insulation and the windows.
- Save on areas you can upgrade later: the kitchen, carpets or floor material
- Cut costs early and be honest with yourself. The buck stops with you, so make changes sooner rather than later, whether relating to contractors, materials, or unforeseen circumstances.