All About Top Down Construction: Procedure, Benefits, and Who Needs It

 A reverse method, top down construction is about constructing a structure from top to bottom. It may also include basement and deep excavation. In this guide, you’ll learn all about the construction approach to understand whether or not it is suitable for your next project.

The standard construction method, bottom up construction, includes building the lowest level first and then moving to the top of a building. If  there’s a basement, the convention method covers the basement part first and moves to other levels after that.

What is Top Down Construction, and When is it Important   

The best construction companies like Walsh Construction define the top down approach as a technique to build higher levels before the lower ones. The levels built first work as horizontal frames to support walls. In this, the basement part is excavated after constructing all the other parts of a building.

Although the bottom up construction is simple, it is not feasible for projects where size, time, and laws are the issues. 

Also, the top down construction is highly effective for multiple types of urban structures - underground buildings and subway stations. The approach is used for construction projects with basements where techniques like anchor installation are not possible. 

In this construction method, the building process’ first step is to retain wall installation for future levels. 

Top Down Construction Sequence

The typical sequence in the special construction approach is as follows: 

• Construction of the retaining walls, also known as a diaphragm wall.

• Construction of piles.

• Excavation - first stage.

• Floor slabbing of the first basement. It allows machines to dig deeper for another basement. 

• Excavation - second stage.

• Floor slabbing of the second basement. It allows machines to dig deeper for another basement. 

• If more floors are needed, then the above steps are repeated. 

• Once all the floors are with the floor slab, the foundation slab is constructed and the basement is completed. 

Advantages of Top Down Construction

The obvious advantage of the construction approach is that it enables the construction of multiple basements. Apart from that, there are many other benefits of the construction method, and here are some of them:

• Multi-tasking: It is possible to work on superstructure and substructure simultaneously. It is useful in case of projects with short deadlines. In addition, big projects can use this construction approach to finish the building process quickly.

• Easy Construction: It becomes a lot easier to work on a project. For example, here, temporary popping can be used to quickly finish a floor. After that, the temporary popping can be replaced with permanent slabs. 

• Quality: The construction method offers stiff support to the wall and minimizes its movement, which provides the structure with the much-needed strength. 

Disadvantages of Top Down Construction

As per Walsh Construction, a reputed and experienced name in the construction industry, the top down approach is highly useful in case of projects that require excavation. However, like everything else in the world, the construction method has its own share of cons, which are:

• Complexity: It is more complex than the standard bottom-up approach. Only experienced construction professionals can work on these projects for the desired outcomes. 

• Excavation: Although the unique construction approach is a quick and effective method, the excavation process may slow down the construction process. In addition, the substructure part is slower and limits access.

Conclusion

The top down construction approach is highly useful for building underground structures. Although it is a quick method to construct new structures, only experts can work on these projects. If you believe your project requires to follow the top down method, reach the best construction company that covers these services. All the best!