By: Frank Came, Communications Director. Pacific Northwest Building Resilience Coalition
It has long been recognized that resiliency considerations for the design and construction of new buildings are crucial, given the increasing frequency and severity of climate-related disasters.
These measures include risk assessment, site selection, designing for extreme weather conditions, selecting durable and resilient materials, and ensuring that resiliency codes are being followed for buildings and infrastructure.
What is often overlooked is that these same considerations are equally crucial for retrofitting existing buildings.
Understanding the Importance of Retrofitting
Updating the adaptability and flexibility of existing structures in any city or community is vital in the face of changing climate conditions that can pose serious risks to long-established neighbourhoods.
Retrofitting often involves strengthening and modifying existing buildings or infrastructure to improve the structural integrity, performance, and safety of their occupants.
“It also extends the lifespan of structures and reduces the environmental impact associated with demolition and new construction.
Updating existing buildings can make them more resilient to potentially catastrophic events and facilitate adaptation to changing needs. It also contributes to sustainable development.
This involves evaluating the existing structure, identifying weaknesses or vulnerabilities, and implementing targeted measures to enhance its ability to withstand various loads, forces, and potential hazards.
Retrofitting Against Natural Disasters
Retrofitting can play a crucial role in enhancing the resilience of buildings against floods and temperature extremes. Such measures can make them more resistant to the impacts of natural or human-caused disasters, reducing the risk of damage and loss of life.
Pacific Northwest is particularly vulnerable to earthquakes, and older buildings, especially those constructed before 1945, pose a significant risk. These buildings, often made of unreinforced masonry (URM), are prone to collapse during seismic events.
Techniques for Retrofitting
Several techniques can be employed to retrofit buildings against floods, fires, and windstorms.
Strengthening with Steel or Fibre-Reinforced Polymers (FRP can significantly enhance the load-carrying capacity of existing buildings.
Base Isolation and Damping Systems involve inserting flexible or sliding elements between a building’s foundation and the ground, thereby reducing the transmitted forces during seismic events or other disasters.
Composite materials are used to wrap or jacket existing structural elements, increasing their strength and ductility.
Strengthening the foundation is crucial for the overall stability of a building; techniques such as underpinning, micro-piling, or soil stabilization can be employed to achieve this goal.
Multi-Performance Retrofits
Wall-to-Roof and Wall-to-Floor Diaphragm Connections are crucial for transferring lateral loads during an earthquake.
Retrofits involve adding solid wood blocking between rafters and floor joists and anchoring them to the masonry walls with metal plate connectors and through-wall anchors.
Concrete pilasters can be added to foundation walls to prevent collapse, and a concrete slab can be incorporated to create a foundation diaphragm.
Additional Building Bracing can be achieved through various methods, including repointing, adding grout, epoxy injection, or installing reinforcing overlays such as fibreglass-reinforced laminates or shotcrete.
Benefits of Retrofitting
The benefits of retrofitting buildings against natural or other disasters are numerous. As noted, improving the structural integrity of buildings makes them more resilient to floods and wind storms, ultimately saving lives and reducing economic losses.
Additionally, retrofitting can also lead to long-term cost savings by reducing the need for costly repairs and reconstruction after an extreme weather event.
Examples of Successful Retrofitting
The Florida Building Code is an example of successful retrofitting, with stringent requirements for wind resistance, roofing, and impact-resistant windows and doors.
The Miami-Dade County Building Code is another example, recognized for its stringent standards regarding wind resistance and structural integrity.
Closer to home, Portland, Oregon, is considering providing public assistance to encourage owners to retrofit vulnerable buildings. In Seattle, Washington, the city has identified over 1,100 URM buildings and is considering similar measures.
In summary, retrofitting is a vital process that can enhance the resilience of buildings against natural disasters. By employing various retrofitting techniques, we can improve the structural integrity of existing buildings, reducing the risk of damage and loss of life.
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The Pacific Northwest Building Resilience Coalition represents thousands of private companies committed to enhancing planning, development, and the construction of homes, buildings, communities, and associated infrastructure that can withstand, recover from and adapt to the increasing impacts of natural disasters, climate change, and an evolving urban and physical environment. Follow us at: https://bitl.to/3uwN
