Do I need to remove all old adhesive before tiling?

Whether you need to remove all old tile adhesive before tiling depends on several factors, including the condition of the existing adhesive, the type of new tiles being installed, and the requirements of the tile installation. Here are some considerations to help you decide:

1. Condition of the Old Adhesive: If the old adhesive is in good condition, well-bonded to the substrate, and free of cracks or other defects, it may be possible to tile over it. However, if the old adhesive is loose, deteriorating, or uneven, it’s generally recommended to remove it to ensure a proper bond with the new tiles.
2. Type of New Tiles: The type of new tiles being installed can also influence whether old adhesive needs to be removed. For example, if you’re installing large format tiles or natural stone tiles, it’s essential to have a smooth and level substrate to prevent tile lippage or other issues. In such cases, removing old adhesive may be necessary to achieve the desired tile installation quality.
3. Thickness of Old Adhesive: If the old adhesive creates a significant buildup or thickness on the substrate, it may affect the level of the new tile installation. In such cases, removing the old adhesive can help ensure a consistent tile installation thickness and avoid issues with unevenness or protrusions.
4. Adhesion and Compatibility: The new adhesive used for tile installation may not adhere properly to certain types of old adhesive or may not be compatible with it. In such cases, removing the old adhesive is necessary to ensure proper bonding between the substrate and the new tiles.
5. Substrate Preparation: Proper substrate preparation is essential for a successful tile installation. Removing old adhesive allows for thorough cleaning and preparation of the substrate, which is crucial for achieving strong adhesion between the substrate and the new tiles.

In summary, while it may be possible to tile over old adhesive in some situations, it’s generally recommended to remove it to ensure a proper bond and achieve the best results for the new tile installation. Before making a decision, assess the condition of the existing adhesive, consider the requirements of the tile installation, and consult with a professional if needed.