Tiny-house build
Using a boat hull as a base
THE IONA PROJECT INVOLVED TURNING THE HULL OF AN OLD WORKBOAT ON ITS SIDE ON THE BANKS OF THE WHANGANUI RIVER AND CONVERTING IT INTO A TINY HOUSE. MANY SKILLED TRADESMEN HELPED BRING ARCHITECT ELINOR MCDOUALL’S VISION TO FRUITION. THIS ARTICLE FEATURES THE ARCHITECT’S DESIGN AND SOME OF THE BUILDING CHALLENGES AND THEIR SOLUTIONS.
Architect Elinor McDouall’s vision to transform a 1920s Otago Harbour Board workboat into a tiny house caught the imagination and tested the skills of all the tradesmen who brought it to fruition.
Not your typical wedding cake structure, Elinor’s design turned the Iona on its side and the hull, podlike, now forms the backbone of a unique little bed and breakfast on the Whanganui River, opposite the city’s historic central business district.
Following the curve
Boats are mainly curved, unlike your standard house or commercial building. Elinor wanted to retain the boat shape as much as possible while making something entirely different. The builders and other contractors loved the project even as they wrestled with some of the challenges. How to get your head and materials around curved windows, roof, and walls and make a seagoing vessel weathertight on land?
The project started in earnest in October 2018 and was completed a few months before Covid-19 sent the country into lockdown. Three years earlier Elinor had bought the boat online, sight unseen, from a tug-boat enthusiast in Northland.
“I was fascinated by the idea of making something out of the boat. So I sat down and worked out how I could do that. I asked him how the draught was because that’s really crucial if you’re trying to make it the right way up and do something under the deck. But it was just over a metre so it wasn’t going to be possible.”
Elinor then decided to turn the Iona on its side and explore the design possibilities, making it into a functional, sculptural type work that would both honour the original boat and become something entirely different.
“It’s got particularly pregnant kind of curves in the middle and that’s what I was interested in. It also came when I was watching George Clarke’s Amazing Spaces with my children, and it was a bit of a challenge from them.
“At a deeper level this kind of architecture connects back to the child in me who loved making huts. Instagram is bristling with cabins and tiny houses, so it’s not just me who has a kind of yearning for something like this; people love miniatures and respond to them emotionally.”
The Iona house seems to evoke expressions of delight both from the tradies who worked on it and the general public. The unusual accommodation and site also give tourists to Whanganui a novel place from which to explore the region.
THE SECOND ARTICLE, TO BE PUBLISHED IN THE ISSUE 92 OF THE SHED, WILL FEATURE THE INTERIOR OF THE TINY HOUSE, THE EXTERIOR JOINERY AND THE COPPER WORK, WHICH WERE CARRIED OUT USING SOME TRADITIONAL METHODS AND MACHINERY
Kauri bonus
Despite advice not to buy from her father, a seasoned furniture maker, Elinor bought the boat in 2015 and the 1000m² site on the riverbank.
“Then he became really excited and very kindly offered to freight the boat down. I think it’s probably because of him that I love all this timber. He had a workshop when I was a kid and made spinning wheels, colonial furniture, potting wheels, stilts, mirrors. And he made really beautiful furniture out of reclaimed timber.”
Unbeknown to Elinor, who thought she was just buying the hull, the previous owner had begun restoration, making two cabins with recycled 40mm thick native kauri. Much of this timber was reused in the fabrication of the tiny house. In fact, reuse of a range of different timbers is another feature of the build.
The Iona was stored, drying out for two years, then Paddy O’Donnell’s company, Masterbuilt, removed the superstructure before local crane experts Emmetts craned and trucked it to site, tilting it 90 degrees while in the crane sling.
“Elinor’s design turned the Iona on its side and the hull, podlike, now forms the backbone of a unique little bed and breakfast”
Anti-fouling was also removed, bagged, and properly disposed of. The kauri hull was found to be in excellent condition, without any rot.
“We were employed at the beginning to alter the hull, which we did on the hard stand out at the river mouth — took off the cabin and braced it so it could be turned on its side,” builder Peter Chapman said. “Elinor employed us to close it in and make it waterproof, but being a boat it took a lot longer and we ended up being there through the whole job.”
Peter and James O’Donnell inherited the project when they bought the company from Paddy and renamed it Masterbuilt Building Ltd.
Enthusiasm
Elinor had spent three months doing research and “tinkering around”, drawing highly detailed plans to present to council for consent. Her architectural training had taught her not to design curved buildings, but when she showed her plans to Paddy he came on board immediately.
Elinor said, “It’s been a neat project all along because of all the guys who are involved. When I showed them the drawings they said, ‘Yeah!’ People ‘got it’ right from the beginning. They were able to make the right decisions because they understood what I was trying to do.”
Elinor learned a lot of technical
stuff on the job, looking into the different ways to do copper roofing, waterproofing, and insulation because she wanted to leave some of the hull exposed on the inside. She investigated various methods of insulating on the inside and the outside, taking into account the U value and thermal conductivity.
“I found some really thin materials that NASA uses that have very high values. You don’t have to insulate all areas as long as the overall equation complies. What I was trying to do was to keep some areas completely free of any insulation but I had to overcompensate in other areas. It was really difficult to get it to work.”
She said the boat’s 40mm planking, plus the resin covering, is within the range of Lockwood Homes, which are around 75mm thick and are not insulated. If it felt cool in winter she would cover the exposed hull area with thin pads covered in leather.
Perfect position
Once the external rafters were removed and wheels fitted, the tiny house could technically be towed or transported by road. Elinor designed the width to 4.1m, which is under the maximum 4.5 width, requiring only a single pilot vehicle. Above that there is greater cost and compliance. The flat floor is about 35m² — 48m² including the area from the hull.
Elinor says the ‘rolling stone’ movable house is more of an American thing.
“I think if you have a site, you want to be part of that site,” she said, and the tiny house looks set to stay on the riverbank.
No stranger to the practical side of building, Elinor emptied water and diesel sludge from the hull, filled all the cracks with sealant, and did a lot of the painting. She put the rimu match lining, sourced from a heritage building in Whanganui, through the thicknesser and, with builder Clinton Raymond, put up the Marmoleum ceiling — something she was advised not to do but that has worked beyond expectations. The colour, reflectivity, and leathery look suits the boat/ caravan–style interior.
“I’m stoked with the way it looks. You use contact adhesive and have about five seconds before it goes off so you’ve got to get it in the right place. And all the while you’re trying not to fall off the scaffold from the fumes!”
Stuart Mackintosh of BPL Group designed the structural steel, which was fabricated by Mike Hughes of Emmetts Civil Construction. Keith Turner, a retired builder and boatie who worked for many months on the Iona, explained that there is a large commercial-type engineering component hidden below the floor.
“The whole structure sits on two big
“He had a workshop when I was a kid and made spinning wheels, colonial furniture, potting wheels, stilts, mirrors”
long steel I-beams. They are supported by two other steel I-beams that are attached to four piles that were driven into the ground. They were driven in until they hit something solid and wouldn’t go any further. That’s similar to what they did reclaiming the riverbank by the [Whanganui] city bridge.”
He said the heavy engineering put into a domestic environment has made the structure very secure.
“By driving a steel beam into the ground, you go to where it’s solid, but you get what they call fricative effort. As it’s forced through the ground, the ground grabs it. Every metre of that beam will support so much lateral loading, which is very easily calculated. They just add a bit more to it for security and then pour a concrete pad round the top. It’s a very simple but very effective way that has been used for decades.”
Twisted hull
The recently-installed hull threw them a curveball after the Christmas break. They found it had twisted so much that the stern had moved 14cm away from its support point, meaning a new steel post had to be fabricated to hold it in place.
“Mike was able to achieve an excellent brace by connecting the new post via a gusset to the old rudder stock, a concealed steel shaft that originally ran vertically down to the rudder. It did continue to move a little bit so all the dividing walls had to become brace walls to strengthen it, to make it more rigid,” Elinor said.
Keith wasn’t fazed by the boat’s settling behavior.
“Turning a boat on its side, you’ve got to do extra structural work to make it retain its shape because it just wants to collapse. We put a prop under and pushed it back into shape. The engineers had some concern about the keel still settling, but we’ve built for the worst-case scenario.”
As for the gaps between the planks in the hull, Keith explained that back in the day they would have been filled with string (caulking) so any water that got in expanded and kept it watertight — “the old stuff still works. Because the boat has dried and all the packing has dried, a lot of it had fallen out.”
The hull was sanded and sealed with several coats of sealant then, after it had settled, covered with a more flexible fibreglass matting and a clear resin so that the timber of the hull is visible.
To add detail to the nautical theme, Elinor was given a rope off a local ship for the balustrading and a propeller from a riverboat.
“When I showed them the drawings they said, ‘Yeah!’ People ‘got it’ right from the beginning”
Many challenges
From a builder’s point of view the rustic look with no straight lines and a few gaps here and there was not too hard to achieve but it drew some comments from people disconcerted by the unconventional nature of this new build.
When the deck was built, the materials — cracked and bent 8x6m native Australian hardwood — dictated that crooked was the new norm. The timber is fixed with brackets underneath so there are no fixings on it.
“You can’t walk on it on stilettos,” Peter laughs.
“Some days it was tear your hair out, but many really good guys worked on it and found it interesting and exciting.
“We were also making sure it’s up to code, so we could get a compliance certificate but at the same time making it look like it’s old and fitting into the landscape — which it does pretty well.”
During an early construction site visit Keith showed how the foredeck comes to a point and the deck is rounded for water to run off. That part of the boat, with its angle and curve, was to contain the shower and toilet.
“There will be an angled wall on the back of the toilet but it’s not just going to be angled. Because of the deck behind it has to be curved as well. So you’ve got to match up the top and the bottom. Do you go straight or do you just match that curve so it becomes something that looks correct to the eye? Until you have a proper look at it, you’re not sure.”
Keith has spent his whole working life in the building trade.
“Done all sorts of stuff, fit-outs on boats to high rises and domestic work. It’s nice to be able to draw on that knowledge and use it here. It’s a really interesting project because so many elements keep popping up and you’ve got to be looking ahead so far as well.”
Creative problem solving
Waterproofing, working through the cavities and rain screens, then putting the decorative finish on the rain screens required some curved thinking.
“We weren’t flashing the windows into a weatherboard house but into the curved hull of a boat. We were keeping it compliant — making a house but trying to make it not look like one,” Peter said.
The window jamb was given a groove then a flat flashing, which is sealed to stop any moisture getting through. A cavity construction was built with plywood then another cavity batten system put over that. The horizontal battens form a decorative rain screen only and the actual waterproofing is two rows back with the plywood.
Behind the copper panels, between the windows, are the galvanized flashings, already mentioned, then the 18mm cavity battens and the 12mm plywood. The copper was fixed over that and is purely decorative, sealed to the plywood.
Fitting out the kitchen also called for outside-the-square problem solving.
“Nothing is straight in a boat — nothing’s square, nothing’s level — so fitting a kitchen joinery unit and bench top into the side of the hull and trying to scribe it into the hull with all the ribs still showing was a challenge,” Peter said. “The council was more than helpful — to be able to ring them up and ask them to come over and work through solutions because it’s not the usual 3604 build.”
“The floorboards are recycled timber; decking trusses came from the Majestic Theatre in Whanganui and the posts from Wellington wharf”
Lead the best
Peter said the hardest part was trying to flash the boat to the building. Because the roof was copper they didn’t want to use Colorsteel so they used lead.
“We ended up using the oldfashioned lead — rolls of 150mm-wide lead, moulding it as an up-stand and apron flashing on the hull in 2m-long strips; getting it formed, moving it aside, putting a seal in the gap, then sealing the lead to that. Then above that on the wall, forming the cavity construction — making sure the lead was sealed to the hull, tacking it down; 50mm centres all the way along so it looks like it’s stitched to the hull.”
They used the lead to seal around other protrusions because it was malleable. “We didn’t want to use torch-on membrane — that wouldn’t have looked good,” Peter explained, “but the lead has weathered well. It looks like it has been there for a long time and won’t peel off.”
Lead was also used under the hull to stop any water running underneath and to form a drip edge on the keel.
“It works well, although lead isn’t cheap. Other options would have worked but not been aesthetically pleasing,” Peter said.
“I enjoyed working on it and everybody that worked on the boat could see the vision. They all wanted to be there.”
The windows made by joiner Mark Thompson of The Door Shoppe echo the shape of the boat. Their making is a story in itself as is the copper roofing and other copper work, made by Kerry Buchanan of Wanganui Plumbing.
In the next issue we feature the interior of the Iona along with the joinery and copper work, all of which contribute to making this tiny house a work of art.
“Some days it was tear your hair out, but many really good guys worked on it and found it interesting and exciting” “Nothing is straight in a boat — nothing’s square, nothing’s level”