For Robin Curtis, the key quality of any new home is also the most basic: make it healthy.
Before I spoke with Robin Curtis of Health Based Building, I’d been house hunting in Sydney. Frankly, I was glad Covid was still going, because my mask protected me from breathing in much of the mould I found inspecting bathrooms and bedrooms, some built as recently as the 2010s.
Curtis nods as I recount horror stories. “It’s people like you who make up most of our customers,” he says. “People who are looking at homes and seeing those problems with moisture. While you might expect it in an older home, a lot of these are modern homes and nothing has changed.”
A co-founder of Health-Based Building, Curtis has spent nearly 20 years working on a specification to make buildings better for the people who live in them, without adding to costs or technical difficulty for the people building them. “Most builders operate in good faith. They want to deliver you a home that keeps you warm in winter, cool in summer and costs a reasonable price to build and run,” he says.” It’s just that – as materials suppliers – we hadn’t previously given them the products they needed to do that without creating new problems down the track.”
Curtis was already working on the issue in the early 2000s when the Leaky Homes crisis hit New Zealand headlines. Non-fit-for-purpose materials resulted in buildings that were damp, mouldy and in some cases structurally unsound. Even in less dire cases, too many homes needed dehumidifiers running 24/7. He envisioned homes that were healthy and sustainable, with low energy costs and low effort required to run them.
“I was looking at a lot of systems, but none of them ticked all the boxes,” Curtis says. The Passive House system was great for energy efficiency but the voluntary approach to the materials involved brought homes wrapped and insulated with plastics and exceptionally low air exchange rates that increase humidity levels.
Then, about 17 years ago, he found his missing link. “I was introduced to Magnum Board,” Curtis says.
“That was the product that completed the material mix we required for the Foreverbreathe Specification.”
Let’s pause for two quick definitions. Foreverbreathe is the name Curtis gave to his building system that allows homes to simultaneously ‘breathe’ – with the moisture in humidity able to diffuse through the walls rather than build up inside or on the wall surfaces – and also keep the passive benefits and low additional energy requirements of effective insulation.
Magnum Board is a high-quality sustainable magnesium oxide (MgO) board that looks like plasterboard but acts very differently. Its structural performance is maintained while diffusing moisture and it won’t grow mould. It’s also insect-proof and non-combustible, so suitable for a wide range of lining and building categories.
Curtis was thrilled. He says, “My idea for the Foreverbreathe Specification required a material that was constructed and designed to allow moisture to diffuse through it without that moisture degrading or impacting its performance. Plaster boards have the ability to permeate moisture quickly, but the process establishes mould. Magnum Board, on the other hand has a known diffusion rate and remains stable as a material lining, whether exterior or interior.”
He pauses and laughs – “I realise this is sounding like War and Peace, but it’s actually really simple for the owner or builder, because we’ve built the specification.”
Creating a specification
“No normal person is excited when you say the word specification,” says Curtis. “But it’s essential, because you can give it to a builder and show that the products when used together as specified have been tested and monitored and will give the performance that’s promised over the life of the building.”
“While Magnum Board was a key piece in the Foreverbreathe Specification, it’s a part of the whole. The wall system, for example, uses non-plastic permeable coatings that allow moisture to diffuse through Magnum Board into wool-based insulation that maintains its R rating as it absorbs and converts moisture to gas via its exothermic abilities. Forest-certified timbers are used in the frame, floors and joinery – storing carbon in the building at the same time as minimising the carbon cost of construction.
The delivery of a pleasant, mould-free living environment is the specification’s key goal, but the structure is also naturally more fire-resistant than the typical home and safer for people with chemical sensitivities.
Importantly, Curtis has delivered homes built to the Foreverbreathe Specification at the same cost as a typical new house build, including his own.
“The home I live in was the first one built to the specification in 2013,” Curtis says. “It was evaluated closely for three years, and we’ve kept going with monitoring, so we have years of data to back up our claims.”
The team quickly built another home for Curtis’s fellow director in the business, then more in the local area, then the Foreverbreathe Demonstration House – “we couldn’t keep up with the number of people coming through our own homes to see how the specification worked and what the home was like to be in,” says Curtis.
Most of the first 50 homes were (with privacy protections) monitored to add to the pool of data and show that the specification would return consistent results with different builders (there are currently 550 builders on the books) but, as Curtis says, “It’s gone past the point where everyone building to the specification has to engage with us. They buy the materials, we educate new builders and architects coming into the system and it has a life of its own.”
The monitoring is integral to each Foreverbreathe home. Unobtrusive domestic units keep track of the air quality and real-time data capture lets the homeowners see how their home is performing and respond if changes to ventilation are needed. “It’s not a highly technical response,” says Curtis, “often it’s opening a window.”
One tracking metric on the monitor is the Virus Index, which indicates how likely virus spread is under particular conditions of temperature, humidity and ventilation. Moisture levels, dust and toxins including CO2, carbon monoxide and VOCs are also monitored. “Some of the people who are very keen on the system are ones who’ve really responded to that air quality message,” Curtis says. “Particularly in the US, there are a lot of people with chemical sensitivities who are looking for a better way to live and that market is desperate for healthy homes.”
Building the business
Taking the specification out into the marketplace has been a mixture of show and tell. “We have a lot of information online, but 90% of people demanding the system specification have visited the Demonstration Home, with many flying in to see it,” says Curtis. “It’s interesting that the owners and builders have very much driven this uptake. It hasn’t been the architects and certainly not the government who have been responding to the health impacts of mould and other toxins.”
That said, in the years since the Foreverbreathe Specification began, Curtis has seen architects and builders working with it and delivering quality homes into the marketplace across New Zealand and now coming into Australia.
“Much of that is because we focused so intensively on testing the products and systems when setting up the specification,” Curtis says. “Magnum Board, for example, is the most intensively tested board product in the world and we had to do that because it is competing directly with major brands and making big claims about its performance, so we had to deprive them of any pathway for coming at us disputing those claims: we have data to back it all up.”
The system itself is fully tested, with external authorities adding endorsements and all components fully compliant with building codes. Additionally, the many homes sharing their monitoring include a wide range of families – far from laboratory conditions!
One of the most attractive features of the specification for builders is that, unlike a Passive House Specification, there’s no demand for specialised construction when it comes to airtightness and sealed windows and doors. “We’re looking at 2.6 air exchanges per hour,” says Curtis. “That’s enough to give significant energy efficiencies in the house, but it’s well within the average builder’s abilities. The humidity reduction is very important when the aim is to increase energy efficiency; that outcome is achieved efficiently when vapour diffusion abilities are built into the structure and the structure is not establishing high levels of humidity in the first place.”
In addition to houses built under the specification, others have had their wall systems converted to Foreverbreathe, which significantly improves both air and insulation performance without requiring a knock-down.
“We’re all supposed to be moving in the direction of sustainable development,” Curtis says. “Yet so many homes only last 15-40 years. We’re aiming for much longer than that, and at the end of that building’s life, the specification has almost entirely reusable, recyclable or compostable materials.”
In New Zealand, Curtis has partnered with 112-year-old building firm Hardie & Thomson to form Health Based Building which has been focused on responsible building and lowering the negative impacts of the construction industry.
“Almost all of our homeowners want their homes built to the specification for their and their family’s health,” says Curtis. “But the sustainability side is another draw – we give people a way they can act on their beliefs. And it’s not just recycling or saying no to plastic bags; it’s a whole house.”
Piece by piece
Under the Foreverbreathe Specification the components are designed to work in concert. Individual products on the specification, such as the following from the Demonstration Home, may improve a home’s resistance to mould and other toxicities, but only building to the specification will allow them to work together to both minimise air exchange for maximum insulation at the same time as diffusing moisture, for minimal humidity. Find the full ForeverBreathe Specification at www.healthbasedbuilding.com
|LVL foundation timbers||LVL or solid timber foundations start the building on a sustainable footing.|
|Magnum Board flooring underlay||This MgO board is sustainably produced without harmful chemicals, mould- and insect-proof and has high moisture and impact resistance.|
|LVL portals and framing||LVL delivers long lengths with precise engineering qualities and gets the most economical use from the wood fibre.|
|Coloursteel roofing||Highly durable and recyclable roofing with coatings that allow up to 72% solar reflectance to help with insulation.|
|Velux ventilation||A mix of solar-powered skylights, roof windows and the Velux Active indoor climate control system delivers light, fresh air and summer cooling or winter warmth as required.|
|Rigid air barrier||Magnum Board is used again because it allows the house to breathe, without holding moisture.|
|Flashcard flashing systems||Suitable for use with Magnum Board and various cladding profiles.|
|Terra Lana insulation||Made of natural wool fibre, which is hygroscopic and can absorb and release moisture from the air without impacting its R-value.|
|Foreverbeech solid windows and doors||Sustainably harvested, Class 2 durability timbers, with frames and glass to support the home’s insulation.|
|Magnum Board soffit lining||Provides long-lasting mould- and rot-proof protection for eaves.|
|Exterior claddings||A range of sustainable finishes that allow the walls to breathe and maintain durability are used, including Earthen radiata and Magnum Board weatherboards. As with the wall system, these are reusable, recyclable or compostable materials.|
|Exterior coatings||The coatings are chosen to perform their job well, but without a plastic coating that prevents moisture diffusion. Foreverbreathe Exterior Oils are used on the timber and 100% solvent-free Foreverbreathe Silicate Paint on the weatherboards.|
|Interior wall and ceiling linings, including wet areas, bracing and fire rating||Magnum Board again. Its non-combustible qualities come into their own here.|
|Plastering||FX Super Base Coat and Topping Compound X – formulated for use with Magnum Board.|
|Interior floors, panelling, profiles and joinery||Foreverbeech and sustainable Plytech plywood, which uses plant-based adhesives.|
|Interior coatings||VOC-free and solvent-free Foreverbreathe Interior Wall and Ceiling Paint, which is vapour permeable and comes in a range of dozens of colours including naturals, brights and muted, plus Foreverbreathe Interior Oil coatings.|
|Monitoring||U-Hoo Indoor Air Quality Sensor monitors humidity, particulates, levels of CO2, CO and VOCs and much more.|
Image: The Foreverbreathe Demonstration Home in Christchurch New Zealand is light, airy and dry, thanks to its materials.