Last month, on March 24, residents of several counties reported having felt the tremor that shook the country at around 7:30pm. The earthquake, which was confirmed by the Kenya Meteorological Department, affected parts of Nairobi, Nyeri, Mombasa, Kiambu, Makueni, Nakuru and Naivasha. Thankfully, the magnitude 4.8 earthquake was mild and left no destruction in its wake.
But the occurrence is enough to raise the question: What if it were an earthquake of a larger magnitude? Would our buildings have been strong enough to remain intact in the aftermath?
News of a storm wreaking havoc in the southern part of the continent was perhaps even more troubling. Cyclone Idai caused catastrophic damage in Mozambique, Zimbabwe and Malawi, leaving more than 800 people dead and hundreds more missing by the start of this week. Though Kenya has had its own fair share of perennial floods, would our buildings still hold were they to get exposed to a cyclone of similar magnitude?
Mr Franklin Mwango, a lecturer and the chairman of the Department of Architecture and Interior Design at Kenyatta University, is pessimistic about our chances in the face of disaster. This, Mr Mwango notes, is because most buildings in Kenya’s urban centres such as Nairobi and Mombasa were put up many years ago. The materials and engineering methods used back then, he says, are largely outdated.
Mr Douglas Githaiga, a construction consultant and freelance quality assurance officer, is equally doubtful whether our buildings would fare well in the face of disaster. “Though we have been blessed enough not to experience events such as disastrous earthquakes, tsunamis and cyclones, the risk of such events happening, though slim, still looms,” Mr Githaiga warns.
The two professionals are of the opinion that it is time for Kenyan builders to adopt resilient construction techniques. Putting up a resilient building, Mr Mwango says, means considering not only how the building would fare under common use, but also putting in mind unexpected affronts from environmental and man-made forces that might compromise the structure’s integrity.
While praising Kenya’s building code as a guide to help builders put up architecturally sound buildings, Mr Githaiga points out that potential builders with resilience in mind should endeavour to go above and beyond the minimum requirements of the stipulated building codes. He points out that even though resilient buildings will inevitably end up costing more, the extra mile may one day mean the difference between life and death.
“The peace of mind of having a building strong enough to withstand major storms, earthquakes and even terrorist activities cannot be overstated,” Mr Githaiga adds.
SITE BACKGROUND DETAILS
The first step towards putting up a resilient home, Mr Mwango says, is to find out as much background information about the site as possible. “A thorough site analysis of the area in which you’re building is paramount. If your architect only visits the construction site during the dry months from January to March, he might end up designing a house that, come the rainy season, gets flooded. A site analysis running back to the past 12 months is often used as a standard, but cautious builders can request a site analysis from as back as ten years prior, just to avoid any surprises,” the lecturer notes.
Mr Mwango gives the example of the Great Flood of New York that struck the largest city in the United States in 1913. He says, “Records have shown that the flood comes once every 100 years. It has been slightly more than a century since the storm last caused havoc, and authorities estimate that it might descend upon the city any time now. This time, though, New Yorkers want to be prepared for it. As such, over the past 15 years or so, the authorities have been ensuring that old buildings have been reinforced to be able to withstand a flood of such magnitude.”
Mr Githaiga says that before building, one should request a building professional to prepare a report that covers an area’s exposure to risk. A geologist, for example, may determine whether the soil type can support the building, especially in sloppy areas and places that are prone to erosion and mudslides. Weather factors such as wind speeds and average temperatures of an area can affect the type of building that may be suitable for that place. As such, it is always best to look up climate reports before building.
Mr Mwango, an architect, lived, worked and studied near the infamous San Andreas Fault line in California. The western US state is a hotbed for seismic activity, and Mr Mwango experienced a number of them during his time there.
“My university was located directly along a fault line, and earthquakes would often rock the campus in which I worked and studied. However, though the quakes were many and intense, buildings rarely crumbled as they had been put up to be resilient,” he remembers.
“Studying architecture in California, a third of my coursework was on how to design buildings that could withstand seismic activity. These are modifications that Kenyan architects need to learn and embrace too, seeing that a large chunk of our country sits along the Great Rift Valley,” the lecturer continues.
In March last year, cracks formed in several parts of the Rift Valley, most notably a 65-foot-wide crack on the Mai Mahiu-Narok road. David Adede, a geologist who spoke to the Nation after the cracks occurred, blamed the events that threatened to split the Rift Valley in two on volcanic activities beneath the valley.
HOW TO ENSURES STABILITY
The first steps towards putting up a structure that will withstand seismic forces is constructing a strong foundation. This, Mr Mwango says, can be achieved by letting a geologist determine the depth of the foundation, which may be deeper along high-risk areas such as in the Rift Valley.
“A building’s foundation can be joined onto its structure by expansion joints. These expansion joints may include springs that will act as shock absorbers during an earthquake. In such an event, only the foundation of the building would be affected by ground movements, but the rest of the structure will remain intact,” Mr Mwango expounds.
The don points to cross bracing as a technique that can be used to make the walls of our buildings resistant to seismic activity. Cross bracing, he explains, is a system of making a building stronger by joining its columns and support beams using two diagonal supports placed in an X-shaped manner. This technique increases the building’s weight-bearing capacity.
Instead of using common window panes that might crack and shatter thus injuring the home’s occupants during a disaster, Mr Mwango recommends laminated or tempered glass for windows and doors. These, he says, are toughened glasses that do not split into hazardous smithereens upon impact.
For buildings made of brick and mortar, woe betide its occupants should an earthquake of magnitude 6 and above strike. Mr Mwango predicts that in such a scenario, the building’s bricks and blocks would scatter and hurl in different directions, injuring occupants and passers-by. He recommends that Kenyans move away from traditional brick and motor and explore newer and more resilient building technologies such as the use of light-gauge steel and expanded polystyrene (EPS) panels.
The foundation is also the focal point when preparing for water-related disasters such as floods of biblical proportions, cyclones and tsunamis. The architect opines that buildings in areas prone to flooding, such as Narok and Budalang'i, would benefit from raised foundations. These foundations, he says, should be such that they allow excess water to flow right under the building. As such, the foundation will avoid the danger of getting damaged as a result of being waterlogged.
Having a building that can survive even when off the grid will come in handy during difficult times. Mr Githaiga, the construction consultant, suggests that when building, you should consider installing your own electricity-generation options such as solar panels and diesel generators.
Mr Githaiga observes that in many buildings, backup generators, water pumps and other controlling equipment for the building are usually stored either in the basement or the ground floor. He warns that there’s a danger of water flooding these floors during a severe storm and cutting off the power and water supply.
“Building designers should take care not to include backup generators, booster water pumps, internet routers or anything important in the basement. In flood-prone regions, such mechanisms should be designated to the topmost floors,” he advises.
BUILDINGS FOR PROSPERITY
Early last month, dozens of students of St Brigid Nangwe in Kabuchai constituency in Bungoma County were struck by lightning during a thunderstorm while they were going on with their evening preps. The students were later treated at a nearby medical facility. Commenting on the event, Mr Mwango lays the blame on the designers of the school’s building. He opines that disasters related to lightning can be avoided by simply installing lightning arresters on every building in lightning-prone areas.
Peeping into the future, Mr Githaiga foresees extreme weather changes over the coming decades. He says, “Due to global warming, scientists predict that events like hurricanes, cyclones and heatwaves will increase as the planet warms. Although it is very hard to pinpoint exactly what will happen in terms of climate change, chances are that Kenya will be adversely affected, especially by abnormally heavy deluges. While we can do all that we can to slow down climate change, it also behoves us to put up buildings that will stand strong in the face of such catastrophes should they befall us.”
As the chairman of the Department of Architecture and Interior Design at Kenyatta University, Mr Mwango underlines the importance of educating the next generation of building professionals with resilience in mind. “We need to teach our architects and engineers how to design and put up buildings that will last for many generations to come,” he says.
The don adds, “In the event of any disaster that renders a building unsafe for occupation, its occupants need to exit the building in a safe and quick manner. Architects designing buildings should take note to include emergency exit doors that actually work, and install other safety materials in the building such as smoke detectors and firefighting equipment that are easily accessible.”
Should you decide to build the resilient way, an important consideration would be to decide how much money you are going to spend. Is spending more on your house to make it extra-sturdy worth it? What if you go the extra mile and disaster does not strike in your lifetime? Answering these questions, Mr Githaiga says, is tough since it requires predictive knowledge of when the next great flood, lightning strike or earthquake might occur.
“For those who can afford it, they should go ahead and put up a building that has the ability to withstand an act of God. After all, money cannot be compared with the chance of saving a life,” Mr Githaiga says.