THE IMPORTANCE OF GERMAN-FLOOR OR OVERSITE CONCRETE IN A BUILDING

Question: I’m trying to put up a two-flat Bungalow in Lagos. It is already at the foundation stage. I was advised to run German floor after foundation, but considering quotations I’ve got so far, it seems a bit expensive. Another person advised that I should rather spend such money to set blocks and do flooring later. My inquiry into other projects within the site revealed that not everybody did German floor after their foundation. Please, what is the importance of German floor?

-               - Victor.

Answer: Thank you Victor.

The importance of german floor or oversite concrete in a building can’t be overemphasized. There had been a lot of arguments on whether to use a german floor for building projects or not. I have also built too without a german floor in exceptional cases, but this is not the best practice.

On a very solid soil, most people tend to forgo german floor because of the cost of concrete, especially on a one-floor bungalow. However, you must not build in a waterlogged place or area susceptible to heavy settlement without doing german floor.

In other words, german floor is important and very necessary, if you can afford it, even on solid and non-problematic areas.

These are the importance:

(1) German floor stops water from percolating from the soil into the building. It reduces the movement of water from getting to the walls and floor, which may cause damp and result in algae growth around your walls. If the german floor is used with a membrane or nylon or cellophane spread to cover the floor before casting it will reduce water getting up greatly.

(2) The german floor is also a part of foundation; it should be seen as one of the structural elements that make your house to stand. Loads transmitted from the building are also received by the german floor before being transmitted to the foundation. In a raft foundation, it is inevitable to have german floor because you have to blend it with the strips coming from the foundation base, in order to form a mass of concrete that is monolithic and helps to stabilize the building.

(3) For stability. As was mentioned earlier, it is a part of the foundation, and it forms a stable base for both live loads and dead loads in the building. You should be confident while stepping on the floor by making sure you have a solid floor which can also sustain earth tremors or vibrations from machines in and around the building.

(4) When there is a movement in the soil, the german floor helps to redistribute the forces on the building, and spread same around the floor easily which may also help to sustain the building from collapsing.

(5) When there is cracking on the block wall, (for non major cracks) the german floor can serve as a breaking point that will stop blocks from extending crack lines into the other parts of the building; that is, if the crack is up, then it may not extend beyond the german floor towards the foundation, and if the minor crack is from blocks under the german floor, it may not extend beyond it except there is a major defect in foundation due to settlements or improper foundation.

(6) A well done german floor also helps in determining and correcting problems associated with levels when construction is on.

Before your builder cast the german concrete, you have to ask him to take the level of the building round to achieve an even plane which will make your house to come out better during construction.

... Source