23 Oct 2023
As a renewable, carbon-storing building material with low embodied energy, wood has major sustainability advantages over other construction materials.
Wood is one of the oldest and most versatile building materials used around the world. With rising concerns over sustainability and reducing carbon footprints, wood is becoming an increasingly popular option for modern green building practices.
Using wood sourced from responsibly managed forests provides tremendous environmental benefits compared to other common building materials like concrete and steel.
For architects and builders in Africa looking to design more eco-friendly, net-zero energy structures, building with wood has many clear advantages.
In this article, we’ll explore the sustainability benefits of using wood, review types of wood construction methods, and discuss key considerations for building sturdy, efficient wooden structures optimized for the African climate.
Sustainability Benefits of Using Wood
Wood offers several important sustainability advantages over other materials:
Wood is a renewable material that can be replanted and regrown relatively quickly compared to the extraction of non-renewable materials like metals and minerals. This makes wood a sustainable construction choice. Responsibly managed timber forests and tree plantations can provide a consistent supply of wood-building materials without depleting forestry resources.
Lower Embodied Energy
The amount of energy required to harvest, process, and transport wood building materials is significantly lower than concrete or steel. Concrete requires vast amounts of energy to heat the materials to high temperatures during production. The extraction and refining of steel is also highly energy-intensive. One study found the embodied energy of wood was just 10% of that of concrete. This greatly reduces the embodied energy of wooden structures.
Lower Carbon Footprint
As trees grow, they absorb CO2 from the atmosphere through photosynthesis and sequester the carbon in their wood. Wood products maintain this stored carbon throughout their lifetime, keeping it out of the atmosphere. Using wood structural elements in place of steel or concrete helps substantially lower the carbon footprint of buildings.
Less Waste and Pollution
Wood production generates far less air and water pollution than concrete or steel manufacturing. Steel production in particular creates substantial air pollution from its high-energy smelting processes. Wood also produces less construction waste. Wood scraps and sawdust can often be recycled into paper products, used as garden mulch, or burned as fuel for heating and cooking. This gives wood greater end-of-life value.
Types of Wood Building Methods
There are several modern methods of constructing with wood:
Mass timber involves using large, solid wood panels for structural walls, floors and roofs. The engineered wood panels are designed for strength and dimensional stability. Types of mass timber include:
Cross-laminated timber (CLT): Made by gluing layers of lumber together in perpendicular layers for two-way structural rigidity.
Nail-laminated timber (NLT): Layers of dimensional lumber nailed together into panels.
Dowel-laminated timber (DLT): Lumber boards connected with wood dowel rods in a laminated panel.
Glued laminated timber (glulam): Vertical wood laminations glue-bonded together in a beam shape.
The large prefabricated mass timber panels are faster and easier to erect than traditional stick framing. They also leave attractive wood interiors exposed for architectural aesthetics.
This uses small dimensioned lumber and wood-based panels, like plywood and oriented strand board (OSB), for framing walls, floors and roofs. The wood frames provide the structure and are then covered with structural sheathing and exterior cladding or interior drywall.
Light-frame wood using standard dimensional lumbers and panels is the most common method of wood construction for residential buildings.
Post-and-beam construction features large wooden posts and beams to create the interior structural framework. Often the posts and beams can be left architecturally exposed rather than covered up. Traditional timber framing joints or modern metal connector plates fasten the structural members together.
New hybrid wood buildings are appearing that combine mass timber panels with light-frame wood or other materials like concrete and steel. Mixing construction methods like CLT floor slabs on top of a steel beam structure allows architects and engineers to optimize the structural performance of each material. Hybrids also facilitate larger multi-story wooden buildings.
Key Considerations for Building with Wood in Africa
While wood offers sustainability benefits, there are some important factors to consider when building with it in Africa’s varied climates:
Controlling moisture is crucial for wood structures in Africa’s humid tropical and coastal regions. Excess moisture can cause swelling, rotting, decay or wood movement. Apply water-resistant finishes on exposed wood. Utilize generous roof overhangs, siding, flashing and drainage to protect wood from rainfall. Allow for adequate ventilation in wall cavities and attic spaces.
Termite and Insect Resistance
Termites are a major pest that can substantially damage wooden buildings in Africa. Other insects like ants and powderpost beetles can also attack wood. Use naturally termite-resistant wood species harvested from certain trees. Treat wood products with preservative chemicals. During construction, properly setup termite barriers like metallic mesh and perimeter chemical treatments in the ground around the structure.
Engineered mass timber can meet one-hour-plus fire resistance ratings, but building codes may require additional fireproofing in larger buildings. Comply with any regional fire codes and regulations for wood structures. Use fire-rated wood products treated with fire retardant chemicals. Include firewalls between units and fire sprinkler systems if required in the building plans.
Consult licensed structural engineers early in the design process. They can recommend advanced engineering techniques for wind bracing, earthquake reinforcement, and heavy roof or second story design for optimal structural resilience. Carefully follow any relevant wind load requirements in the regional building code.
Sourcing Local Wood
When possible, source sustainable timber from responsibly managed local African forests and plantations. Importing wood from distant regions dramatically increases transport embodied energy and emissions. Many African wood species are naturally hard, dense and durable. Support local forestry initiatives and builders to minimize environmental impacts.
Building with wood requires skilled carpenters and tradesmen familiar with wood joinery, framing, and structural techniques. Mass timber panelized methods in particular need specialized expertise. Investing in craftsman education and training will be crucial as wood construction increases across Africa. Look for opportunities to integrate traditional stick framing methods with new technology and materials.
Wood structures lend themselves to creative architectural expression and regional African design influences. Both modern sleek and traditional handcrafted aesthetics can be achieved. Wood’s flexibility helps architects meet their aesthetic vision.
As a renewable, carbon-storing building material with low embodied energy, wood has major sustainability advantages over other construction materials. Both modern mass timber and light-frame wood techniques allow for continued innovation in eco-friendly architectural design.
With proper moisture, insect and fireproofing measures, and by leveraging local wood sources, Africa's architects can employ wood to build resilient, efficient and beautiful structures that benefit the environment while meeting the demands of contemporary construction. The natural beauty and versatility of wood construction also facilitates connecting modern sustainable building practices with Africa’s rich cultural design heritage.