Natural wall (envelope) systems
There are so many options when choosing alternative building systems. Here you can find some helpful information on some of the systems we are most familiar with.
Cob
Cob, a traditional building material made of clay-rich soil, sand, and straw, boasts a unique set of qualities that make it a popular choice for sustainable and natural construction. Its thermal mass properties allow it to absorb and slowly release heat and cold, contributing to comfortable indoor temperatures year-round. Due to its simplicity and the affordability and accessibility of materials, cob has been used for centuries in various cultures, making it a versatile and cost-effective option for building homes, ovens, etc where insulation is not as absolutely essential and thermal mass is more important. Cob structures have excellent durability, often lasting for centuries with proper maintenance, and in some cases more than 1000 years. Additionally, its malleable nature allows for creative and whimsical architectural designs, offering a highly customizable and eco-friendly alternative to conventional building materials.
Light Straw Clay
Also known as "straw light earth" or "clay/straw insulation," is a natural building material with a rich history dating back centuries. It consists of a mixture of straw and clay slip that is densely packed into a wooden frame, creating a structural and insulating wall system. In comparison to straw bale, it’s advantage is that’s all straw strands are covered in clay, a protective and antibacterial, anti rodent, water wicking film, thus it is less vulnerable when properly installed compared to straw bales. With its excellent thermal performance, higher thermal mass and proven durability when properly dried( ie installed in the proper weather and kept dry- being vulnerable only prior to being fully dried after infill), light straw clay is gaining popularity in sustainable construction practices and is included in the building code in a number of municipalities. The straw component provides insulation, while the clay acts as a binder, resulting in a breathable and durable wall material. This combination of qualities makes light straw clay an excellent choice for creating energy-efficient, non-toxic, vapor permeable buildings using framing systems not very different from conventional balloon framing. Its use is rooted in tradition, particularly in Germany. It also lends itself to ‘eco renovations’ of existing homes, making it a valuable asset in the quest for sustainable architectural solutions.
Chip Slip
Basically light straw clay, but with woodchips. It has all the same qualities, but uses what is often a waste product from forestry. Chip Slip is usually best with longer woodchips for more of a ‘matrix’ or ‘web’ structure. A great option where this resource is plentiful.
Strawbale
A construction method that utilizes bales of straw as the primary building material stacked like bricks ( though sometimes used in a system where bales are instead stacked in collumns between framing members). This simple wall system approach offers excellent insulation properties, reducing energy consumption for heating and cooling with insulation value between 30-60 R. Historically, straw bale construction dates back to the late 19th century when settlers in the Great Plains used readily available straw to build their homes. Today, it has gained popularity due to its relative affordability, low embodied energy and localized sourcing, and energy efficiency due to high insulative value. In addition to its insulation benefits, straw bale construction also promotes a healthier indoor environment by minimizing the use of toxic materials; however it is important to note the use of agrochemicals such as glyphosate used on non-organic grain farms to equally ripen the grain, so it is important to consider this when choosing organic/non organic grain straw. This building technique can combine many framing systems, making it an attractive option anywhere insulation is key to good performance, and easily adaptable to a conventionally accepted framing solution, effectively acting as an ‘infill’.
Hempcrete
An innovative building material gaining momentum in the construction industry, hempcrete offers a multitude of benefits. Composed of hemp hurd, lime, sometimes clay or other binder and water, cast in place or precast in blocks at a factory, hempcrete exhibits good thermal performance, combining thermal mass ( in the lime based binder) and thermal insulative properies ( in the hemp Hurd) effectively regulating indoor temperatures and reducing energy consumption. It has a low carbon footprint due to hemp's impressive carbon sequestration during cultivation and lime's ability to sequester carbon dioxide during the curing process. Moreover, hempcrete is non-toxic, mould-resistant, and provides excellent sound insulation. a versatile material, it can be used for insulation in wall roof and floor systems and even as a rendering material creating an insulative ‘plaster’. With its renewable sourcing and impressive durability, hempcrete stands as a promising option for constructing eco-friendly and energy-efficient buildings, especially as hemp agriculture (which has the benefits of locking a lot of carbon fast, building soil, and removing heavy metals) and more efficient lime production (the catchment of released co2 and higher efficiency in energy use, as well as the use of renewable energy rather than fossil fuels). Hempcrete is one of the most durable natural wall systems, but it is more energy-intensive due to the use of lime as a binder, in comparison to the use of clay, which does not require kilning.
Adobe
Adobe has a rich and enduring history that dates back thousands of years. This traditional building method, using sun-dried bricks made of clay, sand, straw has been employed by various civilizations across the globe, from the ancient Egyptians and Greeks to many indigenous peoples of the Americas- you will see many adobe brick homes still in Mexico, for example. This sustainable and readily available construction material has stood the test of time, offering some natural insulation value and good thermal mass benefits, effectively regulating moisture and temperature particularly well in arid climates. Today, adobe architecture continues to thrive in places like the American Southwest, South America, and North Africa, as modern builders and architects embrace its timeless appeal and simple method of construction, while many old buildings still stand through out the american continent; a cultural revival of proper building management is however needed as modern cementitious plasters will destroy adobe walls in time, due to not being vapor permeable, but socioeconomic persepectives tend to favor cement as the modern and better material, and traditional skills among lower and middle class are often undervalued, though this is changing. Adobe is less insulative than other materials and must be protected by plaster, a good roof, and a good foundation as it is susceptible to damage by rain like all clay based wall systems.
Clay Plasters
Clay plasters offer a natural and versatile alternative to traditional wall finishes. Made from a mixture of clay, aggregates, various natural or mineral additives and natural pigments, clay plasters provide a breathable surface that regulates humidity and improves indoor air quality. Their softer texture and generally gentler coloration create a warm and inviting ambiance in any space, making them a popular choice for both residential and commercial interiors where a softer, slightly more fragile finish is appropriate. Clay plasters are easy to apply and maintain, so they are quite suitable for diy situations, in comparison to lime plasters. Whether used to achieve a rustic, traditional look or a more contemporary, super smooth aesthetic, clay plasters have become a go-to option for those seeking a distinctive and environmentally conscious interior finish where a slightly softer finish is acceptable. We generally create our own blends using locally available materials but also offer the application of manufactured mixes such as the line of Limestrong plasters, as well as American Clay products.
Lime Plasters
Lime plaster offers a blend of durability, breathability, and versatility that has made it a staple of architectural design for centuries. Its history dates back to ancient civilizations, where it was used to adorn the walls of Egyptian tombs and Roman villas to name just a few. Lime plaster's unique properties allow it to absorb and release moisture, which helps regulate humidity and prevent mould growth, making it an excellent choice for both interior and exterior applications. It is not as vapor permeable as clay, but it is moreso than cement. Its natural white hue provides a perfect base for decorative finishes and the addition of pigments, and its malleability enables intricate detailing and sculpting, though with less ease than clay. Lime plaster hardens back to ‘limestone’ and is much more durable and water resistant than clay, making it a good choice for exterior and ‘wet’ applications, such as kitchens and bathrooms.
Foundation systems
There are many options for lower embodied energy foundation systems. Here are a few:
Rubble Trench
A traditional and environmentally friendly foundation method that offers several notable qualities. Firstly, it provides excellent drainage and ventilation for the building's foundation, preventing moisture buildup and potential damage to the structure. Additionally, rubble trenches utilize readily available materials such as rocks, gravel, and broken concrete, making them cost-effective and sustainable. Their versatility allows for easy adaptation to different soil types and site conditions, making them a practical choice for a wide range of construction projects. Moreover, the simplicity of construction and minimal use of concrete make rubble trenches a suitable option for eco-conscious builders looking to reduce their carbon footprint. Overall, the most locally available and low tech, low carbon footprint foundation to get you to above ground for heavier structures.
Concretized Woodchip ICF
Concretized woodchip insulated concrete forms (ICF) offer a unique combination of durability, carbon footprint, and insulating properties: one brand, Faswall blocks, are rated for r28 and are considered fireproof. By blending recycled woodchips with concrete, this material creates a foundation system using up to 60% less concrete than conventional concrete foundations while maintaining the strength and stability of traditional concrete. The incorporation of woodchip also offers improved thermal performance, making concretized woodchip ICF an excellent choice for energy-efficient construction. Faswall and Nexcem are examples of manufacturers in North America which offer this product.
Foam ICF
Foam Insulated Concrete Form (ICF) foundations are becoming increasingly popular in modern construction due to their superior insulation properties and structural strength over straight concrete. These foundations are constructed using interlocking foam blocks that are filled with concrete, creating a highly insulated and durable structure. With an R-value ranging from 20 to 30, foam ICF foundations provide exceptional energy efficiency, helping homeowners reduce heating and cooling costs. Additionally, these foundations offer impressive sound insulation and have been proven to withstand extreme weather conditions though when unfinished are highly flammable. According to industry data, buildings with foam ICF foundations can experience energy savings of up to 50% compared to traditional foundations, making them a compelling choice for environmentally conscious and cost-conscious builders alike. Though foam is a petroleum-based product, I include this system for its energy efficiency and lower use of concrete, a high embodied energy material. It is not natural, but it is better.
Screwpiles
Screwpiles, also known as helical piles, are an environmentally friendly foundation solution with a low carbon footprint. Unlike traditional concrete foundations, screwpiles require minimal excavation and produce significantly less waste during installation. This makes them a sustainable choice for construction projects aiming to minimize their environmental impact. Additionally, screwpiles are renowned for their ease of installation in most soil conditions, but not all. Their design allows for fast and efficient installation, reducing construction time and labour costs. As a result, screwpiles offer the dual benefit of being both environmentally conscious and convenient for construction projects of many sizes. They are mostly used to support a wooden framework on which the house is built.
Stone Foundations
Stone foundations are a timeless testament to the enduring strength and resilience of traditional construction methods. Dating back centuries, stone foundations have stood the test of time, providing sturdy support for countless buildings around the world. Crafted from locally sourced stone, these foundations offer a natural beauty and rustic charm that adds character to any structure, while limiting the amount of concrete used, and grounding the building in place. Stone is a great foundation system for cob, or strawbale homes, and lends itself well to curvilinear, more sculptural building styles. Its unparalleled durability when properly built and cared for, it’s ability to withstand the elements make it an attractive choice for certain projects, however, stone may require specialized skill in most situations, and not all engineers and building departments will accept it as a foundation system. In certain situations, the use of a rubble trench for below grade, and the use of a concrete ‘footing’ in which the stone is set, as well as the use of steel connections between major stones is sometimes accepted.
Rammed Earth Tire Foundations
Rammed earth tire foundations, also known as Earthship foundations, are a sustainable and innovative construction technique gaining popularity in some eco-friendly building practices. This method repurposes discarded automobile tires by packing them with earth, creating sturdy building blocks. These foundations offer several environmental and practical benefits, such as reducing landfill waste, utilizing locally available materials, and providing excellent thermal mass for efficient temperature regulation within the building. Rammed earth tire foundations are not appropriate in all situations, and some people have concerns about off-gassing from the tires if they are subject to heat and sun, so inform yourself before going this route.
Framing systems
Roundwood post and beam
Roundwood post and beam construction is a timeless and locally sourced building method that showcases the beauty and strength of natural timber in the round. This traditional technique utilizes whole, peeled logs for the vertical support posts and sometimes horizontal beams, creating a striking architectural aesthetic; it is said that wood in the round has 50% more structural strength than milled timber of the same dimension due to the integrity of all the wood fibers remaining intact. The organic and rustic charm of round wood construction adds a warm and inviting atmosphere to any space, whether it's a cozy cabin retreat or a grand, open-concept great room. Though joinery is possible with round wood post and beam construction, it is more advanced than with milled timber framing.
Traditional Timber Framing
Traditional timber framing is a time-honoured construction technique that showcases the artistry and craftsmanship of joinery. Dating back centuries, this method involves carefully joining large timber beams and posts together with intricate, interlocking joinery, rather than relying on metal fasteners. The precision and skill required for creating these joints, such as mortise and tenon, dovetail, and scarf joints, are a testament to the dedication and expertise of the craftsmen who cut them. The resulting structures exude timeless beauty and strength, with well-fitted joints ensuring stability and durability for generations to come. In a world of modern construction methods, traditional timber framing with joinery stands as a homage to the enduring appeal of artisanal techniques and the natural beauty of wood. It is said that timber frames will do better in a fire, as often the same amount of time burning will result in a charred exterior of the timbers, without losing integrity, while a stud frame building would go up in flames.
A timber frame can be located inside or outside the building envelope, and remains visible; it also allows for the building envelope to be continuous, potentially eliminating thermal bridging if the envelope design is appropriate.
Larson Truss Framing System
The Larson truss framing system is an approach to building framing system that eliminates much thermal bridging seen in the single-stud framework. When combined with light clay or other envelope insulation systems, it provides a logical solution for thicker wall insulation and works great when performing renovations where the goal is thicker, more insulative envelopes.
The Larson truss system's two-stud (inner and outer studs, with ‘ladder rungs’ connecting) design allows for easy installation of insulation materials, such as light clay, within the truss cavities, ensuring superior thermal performance and comfort.
