*By John Kusolo*
The Ugandan government has reinforced its decision to ban the use of the steel-timber concrete composite building method, a construction technique that has gained popularity among builders in recent years. The method, which combines timber and concrete to lay slabs supported by steel beams, was prohibited in 2022 over safety concerns. Following further investigation, the Minister for Works and Transport, Gen. Katumba Wamala, confirmed that the ban remains in place due to significant structural flaws.
In 2022, the government initially halted the use of the steel-timber concrete composite method after raising concerns about its structural integrity. Builders using this technique combine timber joists with steel beams to support concrete slabs. This differs from the more conventional method of using only steel and concrete in construction. The government was prompted to act due to reports that this building method lacked crucial engineering requirements and posed significant safety risks, particularly in the context of Uganda’s construction standards.
*Formation of a Technical Committee*
To ensure a thorough evaluation of this construction method, Gen. Katumba Wamala directed the National Building Review Board (NBRB) to investigate the issue. As a result, a 13-member technical committee was formed in May 2023, tasked with studying the materials, techniques, and safety of the steel-timber concrete composite system. The committee’s mandate was to conduct an in-depth analysis and laboratory testing to ascertain the viability of the method.
“The technical committee, from their analysis and laboratory testing of materials, confirmed flaws in this method because it lacks adequate engineering basis, lacks composite action, and lacks consideration for lateral resistance,” Gen. Katumba Wamala explained.
*Key Findings of the Probe*
The committee’s findings revealed several critical flaws in the steel-timber concrete composite method. Among these issues were:
*Inadequate Engineering Basis:* The method lacks the necessary engineering calculations to support its structural safety. It fails to account for important load-bearing capacities and does not meet basic engineering standards.
*Lack of Composite Action:* Composite action, which refers to the ability of different materials to act together in supporting loads, was found to be insufficient in this building method. The timber and concrete components do not work effectively as a unified system.
*Poor Lateral Resistance* : The technique does not adequately address the lateral forces that buildings are subjected to, such as wind or seismic activity. This makes structures built using this method vulnerable to collapse.
*Deficient Hogging Moment Reinforcement* : In structural engineering, the hogging moment is crucial for reinforcing slabs, particularly at points where bending occurs. The method was found to lack appropriate reinforcement at critical points, further weakening the slabs.
*Substandard Weld Connections* : The welds used to connect steel beams in this method were deemed poor, making the connections between materials weak and unreliable.
Another significant concern raised was the use of poor-quality timber, widely available in Uganda’s open market. The method does not specify timber grades or properties, allowing substandard materials to be used in construction, further heightening the risk of structural failure.
Based on these findings, Gen. Katumba Wamala reiterated the government’s position that the steel-timber concrete composite method remains unsafe for use in construction. The minister emphasized that the technique, as marketed and deployed by its proponents, poses unacceptable risks and is not structurally viable.
“Owing to these findings, we are convinced this method as marketed by its proponents deployed in the market with its variations is generally unsafe and not viable from a structural point of view. It therefore remains prohibited,” the Works Minister stated.
The government has issued a stern warning to those involved in the construction industry, stating that anyone found using this banned method will be subject to legal penalties. Gen. Katumba Wamala cautioned builders and building committees to ensure compliance with approved building standards and refrain from approving plans that lack critical design elements.
“Building committees must not approve any plans that are missing vital information such as design reports, connection details, material specifications, and geotechnical investigation reports,” he stressed.
These regulatory measures are aimed at ensuring that all buildings meet the required safety standards to protect lives and property.
The government’s decision to uphold the ban on the steel-timber concrete composite building method serves as a strong reminder of the importance of maintaining safety standards in Uganda’s construction industry. With significant structural flaws uncovered by the technical committee’s investigation, it is clear that this method cannot provide the necessary safety guarantees. The Ministry of Works and Transport remains committed to enforcing the ban and ensuring that all building projects adhere to the country’s strict construction regulations.
This move is expected to prevent the use of unapproved building methods and ultimately safeguard public safety, ensuring that future constructions are built on a foundation of sound engineering practices.
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