08 May 2018

Robert Dunn has created an energy-efficient holiday home property that has been constructed using over 500 bales of straw

Hidden in the Scottish Highlands sits the Jill Strawbale House, an eco-friendly holiday home created by Robert and Justine Dunn. The building uses straw bales as its main form of insulation and exports five times more power than it imports.


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With a background in tropical forest management, Robert and Justine decided to build a highly efficient holiday home to generate income for their retirement over 15 years ago when they bought and renovated an old vicarage with an acre of land.

Copying a remarkable design from Cumbrian-based engineer, Brian Waite, who built the first one to show it could be done, they worked with a local architect to help finalise plans and gain the necessary permissions.

Robert, who did most of the construction along with this family, comments: “Despite having no experience of the building industry, Justine and I were keen to create the holiday home ourselves. By picking a cruck frame design that was easy to erect, we have been able to do most of the work with help from friends and the rest of the family too.

“In the past, we have worked in the tropics and when we came back to the west coast of Scotland, we decided to put down roots in the village of Strontian. We have always been passionate about the environment and knew the holiday home had to be eco-friendly and energy-efficient.

“Standing on top of the hill looking at the view, we were saying to ourselves ‘ah yeah this is in the 10-year plan,’ it was always in the 10-year plan; we always thought this would be a great place to build some holiday lets,” explains Robert.

“So when we unexpectedly lost our jobs, we decided now’s the time. The other thing that pushed us to do this was my back. We were growing organic mushrooms and my back started playing up so I thought we would go into building instead, which has actually been fine for my back.

“I had always been planning to build a straw bale house up there and I was thinking I would do something octagonal, which I guess, is more of what you would expect. More like a single-floor bungalow with a sort of spirally roof – having been inspired by Grand Designs, watching ever since its first series – that’s the sort of thing I had in mind. Four years ago, I was just going through the internet looking at straw bale houses, I was just randomly Google searching, and I stumbled across Brian’s design and I just went ‘wow’, I thought it was just so beautiful – this upside down rowing boat shape was really beautiful and I had always had the idea of creating something with curves, it was just these were curves in different directions. So I just contacted Brian and asked if this is something he could help us with and he said sure, so my family drove down to Cumbria and met him to check out the design and he put us in touch with Touchwood Homes. We decided to crack on and that we would try and build two. So the other one, Jack – because we’re doing Jack and Jill because were up a hill – will have full disabled accessibility, with hoists and a wheelchair lift but other than that it will be pretty much identical to Jill, just a mirrored image. We plan to embark on the second one shortly. I already have 500 bales stored in a barn nearby but most of the materials I already have on site, so it’s just a question of getting on and doing it – it should be quicker than the first build.”

Robert continues: “While we were waiting for planning and building control to give approval, I built a boiler house because we were going to employ a biomass boiler to heat both houses, so that was how I learnt to do blockwork, which was quite hard going. I also built my first roof and tiled my first roof, so a lot of first times for doing things and it’s still there. We actually moved to the ground source heat pumps route as it seems to be a safer and easier thing to do for holiday lets.

“Planning went through incredibly fast actually, without any problems. One of the things I thought would be a problem was the curved roof because the planning officers seemed to say that they liked straight pitched roofs so I thought they might have a problem with this but they didn’t. There wasn’t outlined planning permission for the land, because we are outside the planning envelope for the village but permission had been given for buildings along one side of the road so we didn’t anticipate any problems and, sure enough, there weren’t.”

Robert continues: “Building control took a bit longer. But I think that’s really because of all the details required to get approval. One of the building control officers pointed us in the direction of an architect that had built a straw bale house not too far away from us and proposed that we might want to use that as an example. We actually didn’t have any problems, it took about six months but that’s just the bureaucracy and the paperwork. There were no objections in the village, or from our neighbours, everybody was fine with it.

“We had it planned to be let on the last weekend of March, and we got our building control a couple of weeks before that. Which was good timing! We had a very close eye on the clock but it all worked out fine.

“A challenging aspect of the build was just simply the fact of never having done anything like this. The actual erection of the crucks was relatively simple and straightforward – four or five of us just sort of pushed them up, in about two or three days we had them attached and then a friend of mine said why don’t you try putting polytunnel plastic over it, and so we did. For a while it was the tallest polytunnel in Scotland because we actually went lengthways to go across it, from one side of the building all the way around over the crucks to the other, it was actually too big for the largest sheet of polytunnel plastic, but luckily we could sort of do it at 90° so we were able to cover it. That really helped with doing the straw bale work on the inside – obviously, the straw needs to stay dry. I think the biggest challenge was the curved porch I had added on the side – it’s an addition that’s different from the original design and that’s because we wanted the bedrooms and bathrooms downstairs to have windows through the gable ends and if you had an entry at the end of the building, then that really wouldn’t have been possible. So it works very well visually and it works very well structurally, but it was a real pain to join a curved roof to another curved roof at 90° perpendicular to each other – if you can think about how you would do that, it’s not easy. So, we have smaller crucks that sit on dwarf walls which were 900mm above floor-level, and that keeps the straw up above off the ground and away from splashes and all the rest of it – the crucks sit on the wall plate and the wall plate sits on some Celcon blocks. So you’ve got your smaller crucks sitting on your wall plate in the porch but then if you think about it; the cruck’s closest to the main building; that’s as far as it can go – it still needs to be vertical and yet you’ve got all this space for the porch roof that goes towards the building. So I basically had to fashion an extra cruck that curved in two dimensions, the only way I could do that was to create eight individual pieces of wood that I had to tailor-carve to curve in two directions and it took me ages! That was the trickiest bit.

“Another piece of genius that Brian has come up with, that he has devised as an engineer, is in order to keep the bales dry – they are covered in lime inside and out, they’ve got lime putty on the inside – two layers of that and hydrated lime on the outside, so moisture is absorbed on the inside, passes through the straw and then taken away on the outside. This happens because Brian has fitted a ventilation gap above the guttering and sort of behind the bottom tile, so air can pass under the roof, so this 1/1.5" gap is protected from animals and bugs with a stainless steel mesh, meaning air can pass through between the outside of the lime and the underside of the roof. This means air is always passing the lime on the outside, and then at the roof ridge; it is a ventilated ridge that has been designed between Brian and Dreadnought Tiles – a fairly new system which allows ventilation right along the ridge without any water penetrating at that point; it’s a clever design and, of course, that’s great when you don’t stick a porch in the way, but when you go and whack a porch across one side of the building you stop all your lovely natural ventilation.

“So Brian came up with a good idea to fix the problem. We cut a hole in the webbing. The cruck is made up of the flanges – which are the thin parts at each end and then the bit that joins them which is like a thinner piece of wood and that’s called the webbing, so we cut a hole in that and then placed a flexible ventilation tube so there was horizontal linkage between the ventilation. We had to find a route around ventilation and we managed to. Basically, adding a porch made life more complicated. Having said that, I think structurally it’s very sound because it’s like a brace. The winds that are hitting the other side of the building are hitting it at 90, sometimes 100mph. We have extraordinary winds here. So having a porch at 90° bracing it all I think is quite good – it wasn’t necessarily, necessary but I think intuitively it feels sensible.

“We rather foolishly made the door in the northern side; we’ve had to build an arch doorway,” explains Robert, “so we have a baby arch, then a mummy arch and then a daddy arch – in a three bears kind of way.”

When it came to using the straw bales during the build, Robert explains: “We used simple, rectangular straw bales, not the big circular ones you see in the fields, just the old-fashioned ones. And the bales are pretty much unchanged. They are the same dimensions as your standard straw bale. The only difference is the person who provides construction straw, which is about £5 a bale. What they do on the machine is they turn the density setting up as high as it’ll go, so it’s just before the string will start pinging because it’s so dense. These are construction grade bales. Unlike some straw bale houses, the function of the straw in this house is purely as a filling for insulation, all the structural strength comes from the crucks, I believe each one can carry around 15 tonnes – they are immensely strong. So, because of the shape of the flanges on the crucks, the straw bales sort of slide in and sit happily on top of the previous straw bale.

“The more straw bales I inserted between the crucks the better I got at it and the longer it took me because initially I was just sliding them in and then going and putting the next one in.

Eventually, I realised it worked better if you shoved loads of handfuls of loose straw between the ends of the bales and the webbing of the crucks, so I used a small mallet and a piece of wood and just hammered in the straw so it was incredibly dense – that was partly to improve insulation and the gripping of the straw and cracks have appeared.”

The house features floor-to-ceiling windows offering spectacular views over Loch Sunart and Morven Hills, and sliding glass doors leading onto a balcony. A spiral staircase gives access to the large lower deck with hot tub, dining and seating areas with a chimenea. There is also a telescope to spot local wildlife and to stargaze in the dark skies.

Robert comments: “For the interior, we were looking for a clean, Scandi-chic style. Fairly plain and simple where possible. We wanted something that looked a bit classy and classic and something that’s not going to look too dated in 20 years’ time. I handed that job over to my wife and daughter because they have far more taste than me. My daughter has done almost all of the illustrations in the house.

“The outside we wanted to keep quite simple. It features an amazing armadillo-shaped roof with slate-coloured tiles. In many ways, the house looks more attractive from the back than the front, because it has these nice simple curves; on the front it’s more spectacular from a tourist’s point of view because of the balcony and the hot tub. From an architectural point of view, I think it looks better from the back.

“The curve of the building makes it visually attractive, because curves feel more natural and organic than a straight line.

“We’ve had nothing but positive noises from people who have seen it – nobody has said ‘oh that’s a blot on the landscape’ and it’s actually quite hard to see it; it’s quite well hidden. So I think it fits into its surroundings quite well.

“The property is everything we hoped it would be, it’s spectacular. It draws you in. The upstairs is my favourite bit of the property – it’s the view. We spent a lot of money on the front window. The fact you can look down this enormous room with this beautiful curved roof out to what is basically a glass wall looking out onto the mountains and the loch is spectacular. That upstairs room is the whole point of the building. We are thrilled. It’s never finished, in the sense that things break and stop working, so you never relax.

“My advice for other self-builders would be to go for it if you have the time and the money. We went over budget a bit but I haven’t been brave enough to go through the final costings! The income from the first one is allowing us to pay for the second one. But it’s worth giving it a go, especially because of the pleasure and satisfaction you get from seeing something you’ve done yourself. I think somehow finding that balance of knowing your limits and where you need help and still giving it as much of a go as you can, I think that’s an extremely difficult balance to get right, and I’m not saying I’ve got it right – time will tell. Be honest with yourself and where the limits of your skills are. The phrase I’ve used so often is ‘fools rush in where angels fear to tread,’ and that has been me! I mean what the hell made me try a design that had only been done once before when I’ve got no building knowledge? I was just determined to make it work and so far it has. You have the opportunity to do something really interesting, something wild and wonderful if you do it yourself and you have this enormous satisfaction of stepping back and looking at it and thinking I did that,” concludes Robert.

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