Why RC Roofs Are Vulnerable To Water Leakages


Reinforced Concrete (RC) is a popular material for roof construction owing to their cost effective and durable nature. However, reinforced concrete has been identified to have both pores and capillary tracts, thus making them susceptible to water leakages.

In this article, we cover scenarios whereby poor waterproofing measures have led to leakages from RC roofs.

Why RC Roofs Are Vulnerable to Water Leakages

For starters, we need to understand that water is a highly mobile substance. It is highly capable of travelling through the smallest of gaps in any structure. Furthermore, once it has penetrated the first surface layer, it can travel even further in as moisture or water vapour. 

Since RC roofs have a number of pores, water can enter before travelling with ease from one pore to another. This movement is known as the osmotic effect, which empowers water to flow through your entire internal structure.

This does not mean that RC roofs cannot be made waterproofed, but additional measures will need to be taken. Given RC roofs’ exposure to various elements of the weather such as rain and strong UV sunlight, professional waterproofing techniques must be applied to them.

Poor Roof Fall Design

When a waterproofing contractor mentions fall design, it refers to the designated flow paths that divert rain water away from the roof. In doing so, water can be channelled towards drainage points where they can subsequently be discharged.

If your RC roof has poor fall design, you will find that water would not efficiently flow away from your roof. Instead, it may unnecessarily cover more surfaces or spend more time on your roof. In the worst case scenario, water may even be trapped on your roof, thus leading to a build up in volume.

This occurrence is known as ponding where water builds up within a single space on your roof. Ponding exposes your roof to heavy pressure from water, which in turn increases the chances of seepage. 

On a related note, if your drainage points become choked with debris such as fallen leaves, the same ponding effect may occur. As such, it is recommended that you regularly inspect and clear your drainage points. 

Appearance of Cracks

Cracks occur due to thermal expansion within concrete. When concrete is exposed to the weather, it succumbs to the tension produced by thermal expansion or contraction. Given that weather can cause a change temperature of the concrete by 1 or 2 degrees, the amount of expansion or contraction can be substantial.

When this occurs repeatedly, cracks and voids will form. This occurrence increases its pace over time as water that penetrates the surface initially becomes trapped and contribute to the expansion or shrinkage effects.