Roofs waterproofing: basic aspects

The main threat affecting the envelopes of buildings is leaks. The consequences are often insidious, as the symptoms can take a long time to manifest themselves and, on many occasions, the problem is not acted upon until these leaks are detected in the lower houses, with the consequent degradation that this situation of deterioration may have caused invisibly during all that time.


Roofs waterproofing: basic aspects


Evaluate waterproofing evaluation

To evaluate the waterproofing of a  roof, a technician should be consulted. He or she will assess the conditions and characteristics of the building, the type of existing waterproofing (if any) and any other factors that may have an influence.

Special attention should be paid to the singular points and the joints between walls, where almost all faults occur, such as drains, edges of the walls or joints in the pavement.

On the other hand, whether the roof is ventilated or not will influence the risk of condensations and will also determine the choice of material.


Renovarion of the fountain in Plaça Catalunya in Spain


Systems used for waterproofing existing roofs

There are many waterproofing systems, but it is useful to know the basic aspects of the most widespread ones in order to decide which one is the most suitable for each roof and situation:

  • Chlorinated rubber: it is a quick and easy solution to apply in-situ, as well as being very economical. However, the problem is that it is a short-lived solution that should only be used in emergency cases.
  • Polyurethane-based liquid membranes : they are used for roof waterproofing by applying a liquid material which, when dry, forms a membrane of a certain thickness that acts as a waterproofing layer. This solution is resistant to inclement weather and UV rays, as well as offering continuity on the surface. The disadvantage is that, if it is not applied correctly by professionals, the membrane may not acquire the minimum thickness necessary for waterproofing.
  • Bituminous membranes: it is a very effective traditional system, as it manages to cover and adapt to different situations. The best known are asphalt membranes. However, they must always be installed by professionals, as they require the use of very specific techniques to guarantee their correct execution. Any single small error entails the non-waterproofing of the roof. It should not be forgotten that it is a waterproofing that requires subsequent protection, as ultraviolet rays reduce its characteristics.
  • EPDM (Ethylene Propylene Diene Monomer): it is a system that resists very well to weathering without any need of protection. In addition, it can be easily adapted to different sizes, thus reducing the number of joints,  but it is very important that it is installed by professionals to guarantee a successful installation.

Roofs waterproofing: basic aspects


Advantages of using polyurethane in waterproofing

Polyurethane offers important advantages such as resistance to ultraviolet radiation, elasticity, ease of application and impeccable uniformity due to the absence of joints.

For example, if we compare it with other widely used materials such as rubber, polyurethane has 900% elasticity compared to 340% for rubber, while at the same time it has a glossy finish and much greater hardness. In addition, it is also resistant to the sun and to atmospheric aggressions, maintaining the same characteristics as  day one.

Not only is it advantageous in terms of weather conditions, but polyurethane is also resistant to standing water thanks to its characteristics. And finally, another advantage of polyurethane for use in waterproofing roofs is that it is walkable, allowing light pedestrian traffic.


Would you like to learn more about the Urespray P-500 system? Read our case study: Renovation of the fountain in Plaça Catalunya in Sabadell (Barcelona).

Renovarion of the fountain in Plaça Catalunya in Spain




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