Waterproofing Above or Below Screed: Which is Better?

11th July 2023

When embarking on any construction or renovation project, you should put careful thought and consideration into your waterproofing methods. Waterproofing effectively protects homes, buildings, and structures from numerous types of damage, such as water or electrical damage, mould growth, and general deterioration, which could affect any project’s lifespan and compromise their safety.

There are many different types of waterproofing, however two most commonly used methods are waterproofing below or above screed. In this article, we’ll explore what screed waterproofing is and the pros, cons, and differences between each method to help you find the right approach for your waterproofing needs.

What is screed?

Screed is an important component of flooring installation, where this thin layer of material provides a smooth and even surface for the final floor finish (such as tiles or wood) to be applied over. Screed is available in several different types depending on the project, but most commonly is a mixture of sand and cement that is poured over a concrete floor or slabs before being levelled out for the final layer.

Whether you waterproof below or above the screed is dependent on several factors, such as the substrate structure, how present the construction joints are, and how compatible it is with other materials within the structure.

Waterproofing above screed

When you waterproof above the screed, you apply a waterproofing membrane over the screed layer before the final finish is implemented. Before applying the waterproofing membrane, the screed surface needs to be completely cleaned of any debris, as the waterproofing will dry and cure over this surface before the finish is placed.


  • Can prevent efflorescence from forming on the surface
  • Quick and easy to apply
  • Can be easily maintained


  • Can easily crack if the screed used is not strong enough
  • May not be very durable if many people are walking or moving things around on it
  • Risks water damage if any gaps or cracks in the membrane

Waterproofing below screed

Waterproofing under the screed involves the application of a waterproofing membrane onto the surface of the concrete before the screed is layered on top. The concrete needs to be cleaned of any debris or dust before the waterproofing is applied, as the screed layer and final layer will both go on top.


  • Provides strong durability against general wear and foot traffic
  • Optimum protection against water damage
  • Increases safety by preventing water from seeping into the flooring


  • Longer and more intensive installation process
  • More difficult to repair damages as the layer is underneath the screed
  • Can be expensive to deploy

Which waterproofing method is better for me?

Determining whether waterproofing below or above the screed is better depends on numerous factors, such as the type and purpose of your project, your budget, and the overall flooring system you have in mind.

If you want to implement waterproofing quickly and easily, then waterproofing above the screed might be the better option for you. This also allows you to conveniently access the waterproofing layer for future repairs.

Waterproofing below a screed might be an ideal choice if your project prioritises enhanced durability and protection, as this method is best for protecting against water damage.

Find waterproofing solutions for your needs with ARDEX

If you still need help deciding which waterproofing solution is best for you, speak to our expert team at ARDEX. We are happy to provide you with advice that best suits your needs. We specialise in waterproofing solutions including waterproof coating, liquid applied roof coating, epoxy waterproofing, liquid applied roofing systems, and carpark coating in Hong Kong to make all your construction projects easier and more efficient.


What is the purpose and benefit of waterproofing?

Waterproofing has several benefits. In addition to protecting structures and important objects against water damage, it can also extend the longevity of a building or structure, reduce the need for maintenance and repairs caused by leaks or damage, and enhance the overall property value by being efficient, safe, and durable.

How do I decide whether to waterproof below or above screed?

Each project will have its own requirements and budget, which affects the decision between waterproofing below or above a screed. If you want to implement waterproofing in a shorter timeframe, then waterproofing above screed is better for you. However, if you want more durability, then waterproofing below screed should be considered.

How long does it take to install waterproofing?

The installation time for waterproofing varies depending on the size and complexity of the project, as well as the type of material used. It can take anywhere from a few days to a few weeks.