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How to upgrade existing foundations and columns to increase the number of
floors in an existing building using chemical anchoring.

Eng. Lanka Ramanayaka, BSc(Eng.), PG.Dip(BSE), CEng., MIE(SL), MEC(SL)

PUBLISHED ON July, 2021

Is it possible to add one or two new floors to an existing building ? It goes without saying that land prices have skyrocketed due to the current high demand in the urban environment. Land set aside for a house or other building to be built in such a congested environment is often limited to 10‐15 perches. It is common for a house to be confined to a single storey or two storey building with a land area, depending on the prevailing economic conditions, not only in an urban environment but also in a rural environment.

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Figure 1: Land set aside for a house or other building to be built in such a congested environment is often limited to 10‐15 perches.

But over time, our needs will increase, and it is not uncommon for us to become overwhelmed by the lack of space in an already constructed building.

Even so, owning one is still beyond the reach of the average person. Although the size of the first floor can be increased when there is space on the ground, you who believe in astrology cannot change it at will. This is because changing the first floor of an architecturally designed house can cause astrological defects. But changing the top floor of a building does not cause astrology defects, so adding a new floor is even more advantageous

How do you add one or two floors to an existing building ?

Deliberately performing such tasks is a risky endeavor and the advice of a Chartered Civil Engineer should be sought first. Many things are taken into consideration by a Chartered Engineer. It will be useful for you to be aware of both types of two word expressions.

It goes without saying that the introduction of one or two floors to a building increases the weight added to the lower columns and foundation. The upper load of the building is carried to the foundation by the columns of the building. In some cases, the upper part of the building is designed to be supported by the walls, and in such cases part of the weight of the building is carried by the walls to the foundation. Therefore, columns and walls need to be reinforced to withstand the increased weight of the floor.

But it can be done at a lower cost and more easily by strengthening its columns. The existing foundation must also be strengthened, as the increased weight is now being carried over the foundation by the reinforced columns. Also, since the foundation rests on the ground, the load-bearing capacity of the soil should be tested. This shows the seriousness of the matter. It is important to keep that in mind.

Let us now consider how to strengthen each of these instances i.e. relevant sectors. Let us first discuss how to strengthen columns and walls.

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Figure 2: How the area of ​​the columns is increased.

The weight of the building is brought down by the walls or the concrete columns or by a combination of both methods. To increase the load-bearing capacity of a wall, its thickness or width must be increased. If it is a clay, brick or cement block wall, it can be done by attaching another row of bricks or two to the existing wall. If it is a concrete tower, increasing its cross-sectional area can increase its bearing strength.

Considering the pros and cons of these two methods, we can make a better choice. In general, increasing the area of the walls significantly reduces the space available on the floor. Therefore, if the required area can be increased only by the columns, less space is wasted than by the walls. So there will be more benefit from strengthening the columns.

Let us now consider how to strengthen the columns. As mentioned above, increasing the cross section of the column requires the addition of new reinforcement outside the existing column. The dimensions of the reinforcement should be determined by the civil engineer. The newly introduced reinforcement should be well connected with the existing concrete. The concrete of the existing column should be perforated and the wires should be connected by a chemical bond.

The depth and diameter of these holes depend on the diameter of the reinforcment used, so it is advisable to seek the advice of a civil engineer. Below is a picture of such a fortified column.

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Figure 3: How the area of ​​the columns is increased.

Concreting should be done very carefully. Chip stones (small stones in size) can also be used for concrete. Let us then consider how to increase the bearing strength of a foundation. First of all it is worth knowing about the types of foundations used for buildings. They are,

1. Rubble Foundation
2. Pad Footing
3. Strip Footing
4. Raft Foundation
5. Pile Foundation

Strengthening the foundations 1 and 3 above can be done by increasing its width and increasing the width as well as the length for type 2. Strengthening foundations 4 and 5 was a complex task and is not expected to be discussed here.

The following figure shows how to strengthen a pad foundation.

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Figure 4: strengthening of a pad foundation.

These newly introduced reinforcement must be tightly bonded together as they are stressed. Embedment Depth is determined by the civil engineer.

Whichever way the foundation is strengthened, it all depends on the strength of the soil as it eventually carries the weight of the building to the ground. Therefore, we must keep in mind that even though our needs are limitless, achieving them is limited. However, in such a case, the advice of a civil engineer can be used to reduce the risk and find a successful solution to the problem.

Eng. Lanka Ramanayaka - CEO
Design Knigdom Lk
BSc(Eng), PG Dip.(BSE), CEng., MIE(SL), MEC(SL)
Chartered Engineer

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