Bio-based materials, sourced from living matter, stand as raw materials for construction purposes, exhibiting low embodied carbon emissions across their lifecycle, encompassing manufacturing, transportation, and installation. Emphasizing their breathability and capacity to allow natural airflow and moisture control, these alternatives, unlike oil-based typical parts, do not release harmful chemicals.
The fundamental goal behind utilizing bio-based materials lies in keeping the majority of these resources out of the carbon cycle. They are viewed not only as construction elements but as contributors to the biosphere's regeneration. The focus shifts from demolition and disposal to composting, envisioning these materials as organic growth, fostering oxygen regeneration and habitat renewal in their eventual disintegration.
Today, with an increased focus on sustainability, traditional construction methods, such as straw building, have resurged with vigor, as a methodical and eco-friendly approach to construction, emphasizing its capacity to significantly reduce carbon footprints in modern building practices.
Structure
Wood is predominantly used within the structure; examples include dimensional lumber, dowel laminated timber (DLT), nail laminated timber (NLT), cross-laminated timber, glue laminated timber (glulam), laminated veneer lumber (LVL), laminated strand lumber (LSL), and parallel strand lumber (PSL).
Hemp Block is a bio-based load bearing structural material that is composed of hemp shiv, water, and a lime-based binder. This mixture dries to a hard, porous material within a week, being able to withstand roof, snow, and wind loads.1
Insulation
Substitutes for insulation, such as those derived from bio-based materials, include: straw bale (derived from waste crops like wheat, barley, or rye), hempcrete (composite of hemp shiv and lime binder), hemp fiber batt (composite of hemp fibers, often mixed with recycled polyester), wood fiberboard and fiber batt (crafted from waste wood from coniferous and deciduous sources), cellulose batt (primarily recycled post-consumer paper with fire-retardant), cellulose dense-packed insulation (involves blowing cellulose-based material into construction cavities with specialized machinery), and mycelium (sourced from agricultural byproducts and the vegetative segment of fungi, although remaining within its experimental stage).
Lining
In Ontario, the three primary alternatives highly praised for lining purposes are wood wool panels (consisting of a mixture of wood fiber, cement, and water - an excellent replacement to gypsum board), clay plaster (suitable for interior walls, comprises unfired clays, natural minerals, and pigments), and lime plaster (a centuries-old eco-friendly option, composed of sand, water, lime, and hydraulic hydrated lime, offering benefits such as improved air quality, dampness prevention, and recyclability/reusability).
Cladding
Wood siding offers a range of options, including budget-friendly choices like pine and fir to specialized selections like redwood. The more affordable choices often require more maintenance, needing re-staining every 10 to 30 years to prevent moisture damage, particularly in northern climates. Cedar stands out as an ideal siding option due to its resistance to rot, pests, and weathering. Despite maintenance considerations, wood siding, especially in Canada, is praised for its low carbon footprint, making it a sustainable choice for cladding material.
1. Burkey, Dave. “Hemp Block: A Better Material for Energy Efficient Buildings.” Innovation News Network, July 1, 2020. https://www.innovationnewsnetwork.com/hempblock-a-better-material-for-energy-efficient-buildings/5916/.
