Earthbag Construction – Earthbag construction uses bags (often polypropylene bags) filled with local soils as building material for walls, floors and roofs. The bags are stacked like blocks and can be curved or angled to create domes or vaulted structures. Earthbag building is very inexpensive as the primary material is just local soils which are free. It is also very sustainable as it uses natural materials and the structures have excellent thermal mass qualities for temperature regulation without mechanical heating or cooling. Earthbag buildings stay cool in summer and warm in winter.
Cordwood Construction – Cordwood masonry uses stacks of firewood logs laid transverse and interlocked to create walls. The gaps are then filled with a lime-based mortar. The technique has been used for centuries and results in very strong, fire resistant and air tight walls. Wood is a very renewable resource and the structures excel at passive environmental controls. Houses can be built very inexpensively using mostly local wood cut from the property or obtained very cheaply.
Coppicing – This traditional woodlot management technique involves cutting back broad-leaved tree species like willow or poplar to a low stump. New multiple shoots will regrow from the stool providing a renewable source of timber. Coppiced wood can be used for roundwood construction, fencing, roofing materials and more. By coppicing woodlots near housing developments an endless supply of cheap, locally sourced building materials can be generated with very little ongoing management costs.
Rammed Earth – Rammed earth construction involves dampening soil and compacting it into forms to create load-bearing walls. The soil may contain stabilizers like lime, cement or fly ash. When done properly rammed earth walls are extremely strong, require no wood, are amazingly durable and regulate temperature well. The structural material is just the soil on site so costs can be very low. Rammed earth homes stay very comfortable without using fossil fuels for heating and cooling.
Cob Construction – Cob is an earthen building material made from subsoil, sand, clay, straw and water mixed into a mud mixture and hand-formed into walls. It has been used for centuries worldwide to create very sturdy homes. Cob structures regulate humidity and temperature passively through the thermal mass. Using locally sourced materials like the on-site soils and straw, very inexpensive cob homes can be built by owner-builders.
Structurally Insulated Panels (SIPs) – SIPs are factory-produced wall, roof and floor panels that consist of an insulating foam core sandwiched between two structural facings like oriented strand board. SIPs go together like interlocking building blocks for extremely high-quality, airtight structures that are far simpler to assemble than conventional stick-built methods. They reduce construction waste and allow much faster building at lower costs than traditional building. SIPs excel at energy efficiency, moisture control and comfort without mechanical systems.
Hempcrete – Hempcrete is a building material made from the internal woody hurd of the hemp plant mixed with a lime-based binder. It sets into a hard material that can be used like concrete to construct monolithic, super-insulated and breathable walls. Hemp is a very fast-growing and renewable crop that needs no chemicals and sequesters carbon from the atmosphere at high volumes. Using hemp and lime from local sources allows the construction of very inexpensive, highly insulating homes that are also fire resistant, pest resistant, moisture regulating and thermal mass structures.
Shipping Container Homes – Surplus shipping containers are increasingly being used as attractive, durable and affordable housing units. With steel frames, weatherproof exteriors and customizable interiors, well-designed container homes can be very inexpensive to construct through repurposing unused containers. Located and arranged properly on a site, container homes can be energy efficient and easily assembled modular structures. Adding small built-on components allows plumbing, electrical and living amenities with minimal additional materials.
Straw Bale Construction – Like cob, straw bale construction uses straw (either in bales or loose) as an insulator within walls constructed using a stabilizing matrix like earth plasters or lime-based stucco. The natural fibers regulate moisture and insulation ratings can surpass many synthetic materials. Using straw and earth facilitates the creation of deep-insulated, breathable structures at very low cost if utilizing bales from on-site agricultural wastes or inexpensive locally sourced bales. Advanced straw bale techniques like Nebraska construction create highly durable load-bearing walls.
The utilization of materials-efficient, passive design principles and available local resources allows the development of homes that are extremely affordable to both construct and maintain. Focusing on natural, renewable and recycled materials that require little processing keeps costs minimized. Locating housing appropriately, combining uses like housing with agriculture and using land sustainably maximizes affordability and liveability long term in an environmentally sensitive manner. With education and incentive, many of these techniques could be applied at scale to address global shortages of adequate living spaces.