Hello friends, welcome to my blog; Today I want to answer a question that I am always asked in my profession, which is that due to the heavy rains in my region, people have filtration problems, especially in concrete slabs.

And it is that, by leaving the slab as a ceiling, a serious mistake is made; the slab is not a ceiling, and when it has to be left as a ceiling, most of the slabs have leaks, precisely because it is a structural element and it is not prepared to be left as a roof, that is what roofs are for.

But how to make a slab waterproof, and it is what is usually done on terraces, I clarify there are many ways to do it, but I am going to suggest one that gives very good results and works well.

The first thing we would do to waterproof it is to build a perimeter wall, about 25 cm approximately; secondly, locate one or several downloads, we are going to model it in the center, for example, you can choose any place that meets the needs that are required, sometimes the center will suit you, others on the corners and it all depends on the architecture of the structure and of the slab you have.

A third step is to waterproof everything with an asphalt paint, the entire surface is painted, including the most remote faces that may exist, if it is not done there, the humidity will pass easily.

The fourth step is to cover the surface with a waterproof blanket, with a geotextile membrane, it is not the membrane that we all know that has aluminum on one side, but it is a membrane that contains fiber inside and is much more resistant than an ordinary membrane. that we use to cover a roof, for example, you should look for the one that is specific for terraces.

Once this is done, you must do a hydraulic test, covering the entire surface with water, this implies that you must cover the discharges or discharge mouths; and leave it for 48 hours, if in 48 hours there are no leaks then we can continue.

The fifth step is to place a layer of thermal insulation that could be expanded polystyrene, very hard at least 30 kg per cubic meter, it had to be very very hard, then we are going to make a counter slab that has slopes, slopes towards the mouth ; the minimum slope to use is one centimeter per meter, if they were 3 meters, for example, you need to have a minimum of 3 cm in the highest part, with 3 cm per meter the water flows or drains very well.

As a sixth step, add a waterproof folder, with waterproof cement and everything is waterproofed, in those lines that you see here you are going to make expansion joints, these joints are used so that the subfloor can move freely and does not cause any type of fissure .

The joint is filled with Sikaflex, and it works very well, which is used for terraces, it resists high temperatures; then you place the grid and make sure there are no leaks there, and the crockery is practically waterproofed, this of course has an additional cost and the day you build it up you will have to remove it and eliminate it.

In which it is an expense that you will not recover in the future, then you will have to consider continuing with the structure until roofing or making this investment so that the slab is completely waterproof.

I hope the information is useful when making a decision, do not forget to support me and we will read next time, bye.

All images including schematics, photos and models are mine