How to Install Ditra Over Concrete: Ultimate Flooring Guide

How to Install Ditra Over Concrete?

To install Ditra over concrete, first ensure that the concrete is fully cured, settled, and hardened.

Allow one drying day per millimeter thickness up to 50mm and two drying days per millimeter thickness after 50mm.

Check the relative humidity of the concrete, it should be 75% or less.

Remove any laitance or cement dust using shot blasting machines or handheld grinders.

Clean and seal the slab, ensuring it is free of debris and dust.

Apply a diluted coat of Tilemaster Prime Plus as a sealer, and a second coat if necessary.

Use self-leveling compound to fix any dips or hollows in the slab, spreading it evenly with a spiked roller and priming before tiling.

When tiling, use high-quality tile adhesive and follow the manufacturer’s guidelines.

Make sure to only use Schluter approved substrates and modified thin-set mortars to bond DITRA.

Key Points:

  • Concrete must be fully cured, settled, and hardened before installing Ditra over it.
  • Allow one drying day per millimeter thickness up to 50mm and two drying days per millimeter thickness after 50mm.
  • The relative humidity of the concrete should be 75% or less.
  • Remove laitance or cement dust using shot blasting machines or handheld grinders.
  • Clean and seal the slab, ensuring no debris or dust is present.
  • Apply Tilemaster Prime Plus as a sealer, diluted, and a second coat if necessary.

Did You Know?

1. Did you know that Ditra, a popular brand of uncoupling membrane, was developed by Schluter Systems? This innovative technology was designed to prevent stresses caused by differential movement between the substrate and the tile covering, thereby ensuring long-lasting and crack-free installations.

2. Ditra is made of a unique polyethylene material that contains a mix of cavities and anchoring fleece on both sides. These cavities serve as channels for moisture to escape, making Ditra an exceptional water management system. When installed correctly, water vapor beneath the tile is effectively funneled towards the perimeter of the tiled area.

3. Contrary to popular belief, Ditra can actually be installed over freshly-poured concrete. However, it is crucial to wait for the concrete to fully cure before installing the Ditra membrane. Typically, it is recommended to wait at least 28 days before beginning the installation process.

4. For DIY enthusiasts, a commonly overlooked step when installing Ditra over concrete is the use of a primer. Applying a specialized primer to the concrete prior to installing Ditra helps improve adhesion and ensures a proper bond between the membrane and the substrate, preventing any issues that could arise from inadequate bonding.

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5. Due to their versatile nature, Ditra uncoupling membranes can also be used with other types of coverings, such as wood or laminate. This makes Ditra a versatile option for various flooring installations, allowing you to enjoy the benefits of uncoupling technology regardless of the type of flooring you desire.

Confirming Concrete Slab For Installation

Before you start tiling a concrete slab, it is crucial to confirm that it is indeed concrete and not an anhydrite screed. Anhydrite screed is a type of calcium sulphate-based screed that requires different installation methods compared to concrete.

To confirm the surface material, you can visually inspect it for characteristics typical of concrete, such as a gray color and a rough texture.

Allowing Proper Curing And Drying Time

Once you have confirmed that the slab is concrete, it is essential to allow it to cure, settle, and harden before installing the tiles. Freshly laid concrete needs time to dry out fully, and this process can vary depending on the thickness of the slab.

According to industry standards, it is generally recommended to allow one “drying” day per mm thickness up to 50mm and two “drying” days per mm thickness after 50mm.

By following these guidelines, you ensure that the concrete reaches the desired moisture content before tiling. Proper drying time prevents potential issues with the tile installation, such as:

  • Tiles cracking
  • Adhesive failure due to excessive moisture in the concrete.

Ensuring Evaporation Of Water In Concrete Slab

One crucial step in preparing the concrete slab for tiling is ensuring that the water inside the slab has evaporated. Excess water can lead to excessive moisture in the slab, which can cause tile adhesive failure or mold growth. To allow proper evaporation, it is recommended to conduct a moisture test, such as the plastic sheet test, to ensure the concrete has reached an acceptable moisture level.

Additionally, it is essential to create proper ventilation during the drying process. Open windows and use fans to facilitate airflow, which helps expedite the evaporation of the water in the concrete. It is crucial to wait until the moisture content of the slab is within the recommended range before proceeding with the tile installation.

Checking Relative Humidity Before Tiling

It is important to consider the relative humidity of the concrete slab before tiling, in addition to evaporation. Schluter Systems, a reputable manufacturer of tiling products, advises that the relative humidity should be 75% or lower before starting the tiling process. High humidity levels can result in adhesive failure and other problems that may jeopardize the durability of the tile installation.

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To accurately measure the relative humidity, it is recommended to utilize a moisture meter specifically designed for concrete. This ensures that the concrete slab has reached the appropriate dryness level to serve as a suitable substrate for the tile installation.

  • Checking the relative humidity is essential before tiling to avoid potential issues
  • Schluter Systems recommends a maximum relative humidity of 75% for the concrete slab
  • Excessive humidity can lead to adhesive failure and the compromise of the tile installation
  • Use a concrete-focused moisture meter to accurately measure the relative humidity.

Removing Laitance For A Clean Surface

Laitance, also known as cement dust, is a thin layer that forms on the surface of concrete after pouring. It can interfere with the adhesion of the tile adhesive, resulting in a weaker bond between the tiles and the concrete slab. To ensure a clean and optimal surface for tiling, it is necessary to remove the laitance before proceeding.

There are various methods for laitance removal, including:

  • Shot blasting machines: an effective technique that uses small steel shots propelled onto the concrete surface to remove the laitance.
  • Handheld grinders with diamond cup wheels: allows for mechanical grinding away of the laitance.

Removing the laitance not only enhances the bonding between the tiles and the concrete, but also creates a smoother and more even surface for tiling.

Preparing The Slab With Sealing And Leveling

To further prepare the concrete slab for tile installation, it is crucial to clean and seal the surface. Start by ensuring that the slab is free of debris and dust, sweeping or vacuuming the area thoroughly. Once the surface is clean, seal the concrete using a suitable sealer, such as Tilemaster Prime Plus, diluted at a ratio of 1 part sealer to 3 parts water.

Applying a sealer is essential for multiple reasons. It helps to prevent water penetration, strengthens the surface, and enhances the bond between the concrete and the tile adhesive. After the initial coat of sealer, it is recommended to apply a second coat if necessary, ensuring full coverage and an even layer.

Furthermore, if there are any dips or hollows in the concrete slab, it is essential to use a self-leveling compound to fix them before tiling. Self-leveling compound, such as Tilemaster LevelFlex, can be applied to create a level and smooth surface for the tile installation. Use a spiked roller to spread the self-leveler evenly and prime the surface before tiling.

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By following these steps, you will have a properly prepared concrete slab as a solid foundation for the installation of Ditra and your desired tiles. Remember to always use high-quality tile adhesive, such as Tilemaster Rapid Setaflex, to ensure a successful and long-lasting tile installation.

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Frequently Asked Questions

Can you install tile directly on concrete?

It is not recommended to install tile directly on freshly laid concrete. It is essential to give the concrete sufficient time to cure, settle, and harden before applying tile. To ensure a successful installation, it is generally advised to allow one day of drying per millimeter thickness of concrete, up to a maximum depth of 50mm. This will provide a solid foundation for the tile and help prevent any potential issues in the future.

What do you put under Ditra?

Ditra is a type of underlayment system commonly used in tile installations. It provides support and acts as a moisture barrier. To ensure proper installation, it is recommended to use Schluter ALL SET Thin-set Mortar under Ditra. This specialized modified mortar is designed to work effectively with all DITRA and KERDI products. Its unique engineering ensures a strong bond between the underlayment and the substrate, promoting durability and long-lasting results. Whether it’s DITRA, DITRA-HEAT, KERDI, or KERDI-BOARD, all types of Schluter-Systems thin-set mortars can be applied underneath for optimal tile adhesion and overall performance.

Why is my DITRA not sticking to the concrete?

Another possible reason for DITRA not sticking to the concrete is improper surface preparation. If the concrete is not clean, smooth, and free of dust or debris, it can prevent the thinset from adhering properly to the surface. This lack of adhesion can lead to the DITRA not sticking securely to the concrete, causing it to peel off over time.

What type of mortar do I use for DITRA?

When installing DITRA over plywood or OSB, it is important to use a modified thin-set mortar that meets the requirements of ANSI A118.11. This type of mortar provides the necessary strength and adhesion for proper installation. However, if you are setting DITRA over concrete or gypsum, it is recommended to use an unmodified thin-set mortar that also meets the requirements of ANSI A118. This ensures a secure bond without compromising the integrity of the substrate.

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