As someone with no previous interest or skills in DIY, Passivhaus Consultant Es Tresidder explains why he went about changing that for his own deep retrofit project.

Interview with Es Tresidder

After getting a degree in ecology Es's journey to low-energy buildings incorporated time working in an earthship, and teaching children in schools about recycling. There then followed an MSc at CAT (Centre for Alternative Technology), and a PhD on optimisation of low energy building design at De Montfort University.

Initially sceptical about Passivhaus, his interest grew upon interacting with the ‘Passivhaus community' on Twitter. He then completed the Passivhaus Designer course, which he credits with teaching him more about building physics in two weeks than he learnt about in the entire duration of his MSc and PhD.

Es Tresidder now has his own consultancy Highland Passive and is in the final stages of retrofitting his home in Fort William, Scotland.

We caught up with him in the early stages of his EnerPHit project.

A good location can lead to a more sustainable lifestyle

Es and his family moved to the area so they could pursue their love of outdoor activities – climbing in particular – and they bought this 1970s timber frame house as a temporary measure until they could find a property to retrofit or a plot on which to build from scratch. It was however in a perfect location for them: walking distance to both primary and secondary schools, a 5-minute walk to the train station, safe cycling routes into town, and facing out to Ben Nevis.

If you want to retrofit, seek a property that needs work doing anyway

Normally if you're planning to take on a retrofit project, you'd look for a cheaper property with obvious signs of dilapidation. However, this house seemed on the face of it to be in a fairly good condition, which made it difficult to justify any extensive works. But once they started scratching away at the surface they discovered some bigger issues with damp and mould. They had also outgrown the house as it was and needed more space. So the decision was made to stay put, extend upwards and retrofit the whole house to EnerPHit standard.

Part of the reason for Es getting hands on was that he was interested in upskilling as a professional. He wanted to learn more about the practical side of tackling a retrofit so that he could help other people who were going to do it.

Never be afraid to get input from people with more experience

Beyond wiring a plug, unblocking a sink and changing a light bulb, Es had very little inclination or ability when it came to DIY.

In order to learn and upskill, he sought out people who knew more than he did and asked for guidance. His father, a retired carpenter, and a neighbour who was an experienced DIYer were regulars to call upon. Beyond that, YouTube tutorials were extremely helpful. While Es lacked practical skills and experience, he did have plenty of theoretical knowledge and a logical brain for working out sequencing and consequences of doing something.

Jobs he tackled himself included tearing things down, pulling floorboards up, putting in the insulation and doing the airtightness, and doing the MVHR installation. He did however leave the complicated work, such as building walls and taking off the roof, to the builders!

Make sure you have the right tool for the job

One of the things Es learnt early on was how important it was to have the right tools for the job. Investing in a good quality drill early on for example was essential.

Having spent a couple of weeks taking down half of a fake stone wall, initially with a lump chisel and hammer and then an impossibly heavy drill, he borrowed an SKS drill that finished the job off in an afternoon! From that point on he decided that if it was clear that there was a tool he needed, and he didn't have it or wasn't able to borrow it, then he would buy one. If he didn't need it at the end of the project then he would sell it.

Be prepared that some things may not go to plan

On one occasion Es mistakenly cut through a mains water pipe, rather than a radiator pipe!

A particularly difficult time was when they removed the roof, shortly before an incredibly wet May. Sadly, all the insulation Es had laid in the floors, together with the original floorboards that he had painstakingly taken up and re-laid, were destroyed and had to be replaced.

Working alongside a building team presents challenges

For the bigger structural changes Es engaged a local building contractor.

As Es was keen to do the airtightness and insulation work himself, he soon realised that he couldn't keep up with the builders.

For example, Es hadn't finished the insulation when the builders were ready to put up the plasterboard. The knock-on effect was jobs were done out of sequence and they were unable to do an interim air test.

The alternative would have been to spend time upskilling the builders in how to do the airtightness and insulation to Passivhaus standard.

“The difficulty with that, is that because this was a retrofit project, some of the airtightness was just unbelievably fiddly. And even a motivated contractor is not as motivated as the homeowner. I spent so long doing it that I find it hard to imagine that they would do it to anything like that level. But I might be wrong.”

Another option might have been to project manage everything himself. This would mean he could book and pay for services as and when they were required. It might have got round some of the scheduling issues, but would undoubtedly have taken longer.

This radical retrofit will lead to a healthier home

A suggestion from a builder friend was to just put foam backed plasterboard on the internal walls. But once Es started taking the walls apart it became clear how mouldy and damp they were. Using rigid insulation wouldn't really do anything about airtightness. It would also exacerbate the problem by making the damp areas colder and more damp.

Es often felt during the process that what he was doing was radical. Doing it any other way though would result in inferior performance and an unhealthy home.

Removing the roof was radical

Taking the roof off was an expensive move, and one that Es still isn't entirely sure was the right thing to do.

The upstairs rooms in the one and a half storey house had very low head height due to the eaves, which meant there was a lot of space being wasted. Another problem they had was because of where their windows were located, they also missed out on incredible views to the south. Instead of looking at Ben Nevis, they faced a neighbour's gable wall and a not particularly attractive tree.

While the alternative might have been to extend the house rather than raising the roof, Es felt the layout wouldn't have worked as well. They also could have knocked it down and rebuilt, but even with the VAT reimbursement, Es thinks it would have been a more expensive option.

Raising the roof has given them comfortable internal heights of 2-2.4m, and gained useable floor area that they didn't have before.

DIY is time-consuming and exhausting

Es has reached the point where he is so busy with work that, in order to get the project over the finish line, he has handed over some of the traditional DIY jobs to the builders. He has also had enough of doing them! This has included fitting the kitchen and bathrooms, and also the painting and laying flooring.

Generally speaking though, Es quite enjoyed getting hands-on with the project and acquiring new skills. He quite likes the idea of combining a bit of manual work, or the teaching of it, with his desk-based job in the future.

Top tips

• Practice your new DIY skills somewhere where it's not too critical first, in case they need refinement.
• If you're a keen DIYer and have knowledge of building physics then you could do a lot of the work yourself. Doing it without that theoretical knowledge though would be risky. Most people would need professional input to do a deep retrofit safely.
• Don't panic! Keep calm and methodical – particularly when using the very expensive and very sticky airtightness tape.
• Have a mantra reminding yourself how dangerous power tools can be.
• Ask lots of people for help, and don't be afraid to use YouTube.
• It would be worth doing a Passivhaus contractor course. It gives a good grounding of the theory, and also of some of the skills.

Find out more

Visit the website of Highland Passive

Visit the website of John Gilbert Architects

If you enjoyed this episode, you can also listen to some of our other interviews where industry professionals have taken on their own projects:

• Keeping costs down by embracing simplicity – with Kirk Rushby and Polly Upton from Architype
• Is it worth upskilling your knowledge of Passivhaus – with Simon Bell of HLM Architects

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