What’s the Difference Between Water Repellent and Water Sealer?

A water treatment solution is used to protect concrete walls from dampness and moisture that may seep into the wall and cause damage to the wall. Two types of treatment can be used on concrete walls: a water repellent and a water sealer. 

Using treatment on the wall is crucial, not only for protection, but it also makes it easy to clean the concrete surface/wall and may prevent stains from penetrating the surface. By treating a concrete surface/wall with a solution, you may also be preventing future repair costs. 

You may be wondering: are water repellents and water sealers the same? After all, they sound the same. In this article, we will look at the differences between these two solutions, the chemicals that make up each, and how they protect a wall against moisture. 

Are water repellents and water sealers different?

Yes. While these two solutions may sound the same and essentially aim to offer similar protection, the compounds in each of these solutions are different, and how they work also differs. 

Non-breathable water sealants

Non-breathable water sealants are used to treat concrete walls. The sealant is applied to the concrete surface and forms a film on the exterior surface of the wall that is water-tight, making it impossible for water or moisture to enter the wall. 

The problem with this type of sealant is that it will also make the wall impermeable to air movement. If moisture of any kind gets into the wall, it will not be able to evaporate to the outside. Essentially, while the wall may be sealed on the outside, the moisture on the inside will be stuck with nowhere to go and may cause frost damage or even mold growth. 

Furthermore, these sealants are not permanent. It may need to be reapplied to retain its effectiveness.

These types of sealants are typically made with the following compounds:

  • Stearates
  • Urethanes
  • Silicone resins
  • Acrylics

Water repellents

Similar to a water sealant, a water repellent may also be applied to the surface of a wall. A water repellent works quite differently than a water sealant. 

The water repellent will penetrate into the wall, thus making the wall resistant to moisture retention and repelling the water. The biggest difference between the two is that moisture and water vapor are still able to move through the wall as the repellent still allows air movement through the wall.  

This means that there is much less of a chance of moisture or damp building up inside and causing damage to the wall over time. Similar to water sealants, water repellents are not permanent solutions. These treatments will need to be reapplied as well. 

In addition, this type of treatment is less prone to UV degradation.

Water repellents are made up of the following compounds:

  • Silicates
  • Methyl siliconates
  • Siloxanes
  • Silanes

Between the two options, water repellents are promoted more than water sealants due to the fact that water repellents may offer similar protection with less risk.