A building structure lays upon a foundation built into the earth and has foundation walls that hold up and form the support system of the entire structure, when the building has a basement, the basement sits at the lowest point of the foundation. Laying a foundation for a building with a basement can be quite expensive and is a crucial process which when not properly done the building will lack structural integrity and be unsafe to inhabit. As such it would not meet the building regulations and codes. Let’s jump into basement excavation in Kenya.
What is basement excavation?
Basement excavation refers to the process of removing dirt, rock, and other debris by digging out the soil to create a space for the basement.to reduce the excavation costs a basement should be dug out before any part of the building goes up.
There are several methods of carrying out this process, in this article we are going to look at the common methods.
Common basement excavation methods in Kenya.
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Open-cut excavation method
This basement excavation method has two ways of carrying it out. the first one is the slope method, which has the lowest excavation costs, it creates an excavated area with walls on a downward slope, and this method does not require retaining walls to hold back the earth from crumbling into the foundation. The second way to carry out the open-cut excavation is known as the cantilever method whereby retaining walls are used to hold back the earth from crushing. This method is advantageous because you can dig much deeper basements.
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Bracing excavation method
This method is more costly than the open-cut method. It does a good job of reducing strain on the retaining walls by offloading weight from them and transferring it o the horizontal struts installed in front of the wall and run from one end of the foundation to the other
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Anchored excavation method
This method works by driving steel anchors into the soil which also runs through the retaining wall. The anchoring force of the earth provides stability and allows excavation to proceed safely and swiftly. This method works best when the anchors are driven to the bedrock or extremely dense clay.
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Top-down excavation method
This method starts by constructing load-bearing foundation walls and laying a concrete ground floor on top of those walls, then a basement gets excavated beneath the ground floor, this basement excavation method is usually more expensive than other methods but allows upper floors to be built the same time as the basement
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Island method of excavation
This method is one of the safest methods one can clear an excavation in kenya. It involves excavating the basement from the inside out, by starting from near the center of the basement and the excavated materials are then laid into a slope near the structures retaining walls.
How to determine the best basement excavation method in kenya
Consider the following factors when choosing a basement excavation method for residential construction in kenya;
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Construction type
You have fewer options if you are excavating a basement beneath an existing building, and more options when building a fresh building basement.
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Type of soil
The excavation method depends on the soil type beneath your structure, if you are on sandy soil, you will need to excavate deeper to reach the bedrock to properly secure your structure.
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Topography
When building on a flat piece of land, you have more options than when building on a hillside where you need to use the anchored method. You will also need to consider the water table levels.
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Size and scope of the building structure
The size of the building also determines the type of method to use for example tall sky crappers usually excavate via the top-down method. If your building is simpler you have plenty of choices to select from.
Conclusion
The best basement excavation method for residential building construction in Kenya trickles down to the conditions discussed above, and the budget overall. Ensure that you consult a professional contractor for further advice.
