Jeremy Harris continues his story, sharing his experience of being a hands-on self-builder.
Interview with Jeremy Harris
Although Jeremy had never laid a brick or employed builders before, he did have useful DIY experience and had used CAD software at work. Jeremy explains what gave him the confidence to tackle so much of his project himself, adding, “If you require degrees and whatever then the building industry wouldn’t be populated by the sort of people it is.”
Five reasons Jeremy didn’t employ an architect
Jeremy chose a timber frame as he would be building in the autumn and wanted to get the house weather-tight quickly.
- A planning application only requires an outline plan, which he was able to design in AutoCAD.
- The timber frame contractor detailed the build using Jeremy’s plan, adjusting it slightly to fit their 400mm spacing system, showing all the joists and timbers.
- Jeremy prepared the building regulations application himself using those detailed CAD drawings, showing the structure of the house and how it would be built.
- The timber frame contractor offered a package of an insulated foundation system and a frame of large prefabricated panels, delivering a weather-tight, insulated house with guaranteed Passivhaus standards of airtightness. The builder was prepared to have 20% of the total payment dependent on the building passing an air test (which it did, achieving 0.43 air changes per hour at 50 Pascals).
- Jeremy modelled the house in PHPP, but also built his own simpler heat-loss model in a spreadsheet to compare variations (e.g. changing windows)
It’s important to get the groundworks right
Jeremy employed a groundworks contractor to make sure the levels were right and the drainage systems were all put in correctly. This cost about £55,000 and took seven weeks to complete.
They had to remove about 900 tonnes of soil to get the site level, digging it out of the hillside and building a three metre high retaining wall almost a metre thick at the base to hold the ground back.
Project management requires knowledge and confidence
Although initially lacking the confidence to manage the whole project, once Jeremy had gone through the planning process, designed the house without an architect and become familiar with building regulations, he concluded he could project manage the build as well.
Jeremy gave the groundworks contractor complete control of the site, supplying a set of drawings and a specification. So the contractor project managed the groundworks stage. Once completed, site security transferred to Jeremy.
The contract with the timber frame company for the house and garage clarified what they were responsible for, avoiding any arguments down the line. The price was about £65,000.
Purchasing and timing are essential for success
The timber frame contractor needed the window supplier to install the windows before the building could be air tested, so Jeremy had to coordinate this.
Jeremy then instructed a roofing company to use an approach commonly found in France, setting 25 solar panels straight onto the south side of the roof, so they were almost flush with the surrounding tiles. Although the tiles look like dark slate, they are made from recycled car tires and bin bags, are recyclable and met the conservation officer’s approval.
Working alone can slow the project down
Jeremy worked alone installing the plumbing and heating system, laying flooring, fitting curtains and cupboards and decorating. He admits this slowed the project down and recalls running from one end of the house to the other twenty times an hour to put in ventilation ducting on his own. With two people, it would have taken half an hour rather than three hours.
He did get some help where he had to, working alongside an electrician as Jeremy wasn’t Part P certified. And a joiner hung the doors because they’re very heavy.
Hands-on involvement inspires innovative design
Jeremy wasn’t afraid to do things differently and took advantage of emerging products.
- There are no foundations in the ground; they laid a passive foundation. 300mm of polystyrene insulation under the floor of the house sits on packed chippings straight on the ground. Reinforced concrete rafts were set into the polystyrene.
- A little pump circulates water through underfloor pipes so when one area of floor gets sun on it, the water carries the heat to other parts of the house without sun.
- The solar PV panels generate hot water using a new SunampPV system that stores heat in a tiny box about the size of a combi boiler and gives it off on demand.
A self-build can be stressful
Build issues, notably the borehole, led to severe stress. Jeremy says: “You realise that practically every self-builder comes to that stage in the build where it all just gets too much.” Online self-build forums gave him support, as well as ideas and information.
There will be problems and lessons learned
Things didn’t always go to plan with the project:
|Challenge||Why It Arose||Solution|
|Drilling the borehole (supposedly a 1-week job) delayed the build for almost a year||Equipment breakdowns, changes in personnel, and a change of rig that led to some dimensional errors||Establishing the borehole was 20m shorter than needed. Recognising they had made some errors, the company compensated Jeremy|
|Solar gain caused the building to overheat resulting in wasteful cooling measures||PHPP didn’t factor in the microclimate (sheltered valley); heat loss was overestimated and insufficient shading was planned to offset overheating||Films added to the glazing on the south side to reflect heat.
An experienced Passivhaus specialist might have anticipated problems relating to solar gain
|A thermal store for hot water overheated the bedroom to such a degree that it|
cracked an oak door
|The heat losses stipulated on thermal stores and hot water cylinders don’t assume that they’ll contain hot water all day||Unit sold on eBay for use in an old stone cottage|
|Air source heat pump surplus to requirements||The need for heating in the house was overestimated||The pump is used to preheat incoming cold water, reducing the workload of the solar panels|
Ten tips for self-builders
Jeremy says, “the most important thing you can do is research, research, and more research”. Here are 10 tips to take away from his story:
- Check advice is appropriate for your own project
- Do finance checks on contractors
- Agree fixed prices with contractors
- Contracts provide clarity and security
- Staged payments reduce your financial exposure
- A borehole means no water rates
- Prefabricated panels reduce waste and are therefore better value
- Solar panels fitted directly onto roof saved £2,000 worth of slates
- Waiting for your VAT reclaim may take longer than anticipated
- To avoid capital gains tax, sell your existing house before moving into your new build