Written by: Steve Socha
It has now been over a year since the Fort McMurray fire that caused the largest wildfire evacuation in Alberta history. In the wake of such a massive tragedy, we should be searching for the ultimate in resilient re-building.
Exterior insulation wraps the house like a warm winter sweater. Typical construction methods place insulation only between the studs, leaving many pathways (thermal bridges) for the heat to escape. Covering your home’s structure with insulation eliminates these thermal pathways and provides protection for the structure from fluctuating temperatures and prevents unnecessary heat loss.
We propose rock-wool insulation because it is truly non-combustible, is made from upcycled waste materials from the steel industry, and is fully recyclable. All styrofoam and spray foam insulations form a toxic soup when exposed to heat.
We suggest 2x4 studs because they are structurally all that you need. The construction industry moved to 2x6 studs so that we could fit in more insulation. More insulation is needed outside of the structure, not inside. Existing 2x6 studs can be overclad with new rigid rock-wool. New construction can be 2x4 studs, overclad with 6 inches of rock-wool.
Insulate above the Building Code minimum requirements keep the heat in during the winter, and keep heat out in the summer. Many energy consultants now recommend that cold-climate homes include around R-60 insulation in ceilings, R-40 in above-grade walls, R-20 in basement walls, and R-10 below basement slabs—well above minimum building code requirements. This reduces dependence on heating systems, and allows homeowners to stay comfortable longer when the power goes out in an emergency.
Avoid styrofoam and other foam-based insulation products whenever possible. These are highly flammable and toxic, and when sprayed, bind the house together, making it nearly impossible to disassemble and reuse the construction materials.
Instead, opt for fire-resistant, non-toxic, mineral wool insulation such as rock-wool. Made from rocks, the rock-wool fibres can withstand more than 1000°C without melting.
2. Cladding Materials
Vinyl siding is often deemed ‘non-combustible’ because it doesn’t burn. However, it does melt, thus exposing what is underneath to the fire, which is usually combustible. Polyvinyl chloride (PVC or vinyl) is one of the most toxic plastics for our health and the environment, especially when melted.
Similarly, acrylic stucco is preferred over traditional cement stucco for economic reasons, but when it melts, it exposes the white styrofoam underneath, which also melts into a toxic soup.
Go with non-combustible metal siding, or heavy timber wood siding, charred, painted or stained.
For example, Shou-sugi Ban is a Japanese siding technique; a method of pre-charring wood so that the outer layer forms a protective coating, preserving the wood and making it resistant to both decay and to fire. It may be counterintuitive to use wood to protect from fire, but thicker wood members actually provide resistance ratings that are superior to other structural materials due to this outer protective layer.
Select durable and natural exterior cladding materials and treatments to withstand weathering and to extend the building’s lifespan. Upon the end of their required use such materials will ideally be fully recycled and/or returned to the biosphere with positive, rather than adverse, effects.
3. Metal roofing
While the initial investment for a metal roof is more expensive than that of an asphalt shingled roof, the costs are recouped over its lifespan. While asphalt roofs will likely need replacing every 15-20 years, a metal roof can last a lifetime and is practically maintenance-free.
Because of the light color and reflectance, metal roofs help to reduce unwanted summer heat gain, and the corrugations help to naturally ventilate the roof. Metal roofing is also generally made from recycled content, and after its lifespan, is itself fully recyclable.
Another attribute of metal roofing is that it lends itself well to rain water harvesting. With its smooth clean surface, less filtering is required of water from a metal roof, compared to asphalt shingles which can shed small particles and chemicals.
We understand that the house of Liz Haskins and John Dowsett in Anzac was saved from the devastating fire for the simple reason that it is clad in heavy timber siding and has a metal roof. The siding charred, but did not burn; and the metal roof did not ignite. Sadly, the same cannot be said of the vinyl siding and asphalt shingle covered buildings nearby.
4. Passive Solar
Making use of the sun’s free energy will heat your home in the winter, while carefully calculated overhangs for passive solar shading will keep it cool in the summer. This considerably reduces the amount of heating and cooling required from other sources.
Properly situate the building on the site to take advantage of nature’s passive free energy. Careful planning helps to collect as much of the sun’s heat as possible to reduce much of the need expensive heating. By opening the south-facing side of your house, you can directly benefit from passive solar heating with ease. Getting free solar heating is an important step towards resilience.
5. Simple is the New Smart
In today’s language, “smart” means a lot of technology, usually expensive to buy in the first place and expensive to maintain and to operate. The more simple that we can make things, the less expensive they are to buy, maintain, and operate.
We can look to post-Katrina New Orleans as an example of where smart homes have gone wrong. High-tech devices installed in rebuilt homes in the Lower 9th Ward seem like a great idea at first glance. But what happens when these devices break down? The homeowners are left unable to repair a home that relies so heavily on these devices. Sadly, many of these homes are now being abandoned.
Using low-tech methods like the ones described above allow the homeowners to remain in their house when the power goes out. Rather than being reliant on electricity and smart-monitoring, a simple house relies on high levels of insulation, airtightness, durability, and passive design.
Smart thermostats are great for making an existing poorly built building more energy-efficient. But in a rebuilding effort such as Fort McMurray, we should put the smarts into the design of the building in the first place. Then we wouldn’t need smart technology to cover up all of our mistakes.