Can thinset be applied over carpet glue?

If you’re planning on installing tile or any other type of flooring that requires thinset, you may be wondering if it can be applied over carpet glue. While it is generally recommended to remove carpet glue before applying thinset, there are certain circumstances where it may be possible to apply thinset directly over the carpet glue.

1. Understanding Thinset and Carpet Glue

• Thinset is a cement-based adhesive that is commonly used for installing ceramic tiles, natural stones, and other types of flooring materials. It provides a strong bond and prevents tiles from shifting or cracking.
• On the other hand, carpet glue is a type of adhesive that is used to secure carpet to the subfloor. It is usually used in wall-to-wall carpet installations and provides a firm grip to keep the carpet in place.

2. Reasons for Removing Carpet Glue

• It is generally recommended to remove carpet glue before applying thinset for several reasons.
• Adhesion: Thinset requires a clean and solid surface to properly adhere to. Carpet glue may create a less suitable surface for thinset, potentially leading to a weak bond between the tiles and the subfloor.
• Thickness: Carpet glue can create an uneven surface, causing the tiles to be unevenly placed and potentially resulting in gaps or ridges.
• Moisture: Carpet glue is not moisture resistant and can be affected by humidity or moisture from the subfloor. This can lead to the weakening or failure of the glue, compromising the integrity of the tile installation.
• Compatibility: Different types of adhesives may not be compatible with each other, resulting in the thinset not adhering properly to the carpet glue.

3. Exceptional Circumstances

• In some cases, it may be possible to apply thinset directly over carpet glue, but only under specific circumstances.
• Condition of the Carpet Glue: If the carpet glue is in good condition, firmly adhered to the subfloor, and free from any contaminants, it may provide a suitable surface for thinset application.
• Type of Thinset: Certain types of thinset, such as modified thinset, may be more forgiving when applied over carpet glue. Modified thinset contains polymer additives that increase flexibility and adhesion, potentially compensating for any inconsistencies in the surface.
• Testing: It is crucial to perform a test area before proceeding with the full application. Apply a small amount of thinset over the carpet glue in an inconspicuous area and check for adhesion and stability after it cures. If the bond is strong and stable, it may be safe to proceed with the installation.

4. Best Practice: Removing Carpet Glue

• While applying thinset over carpet glue may be feasible under certain circumstances, it is generally recommended to remove the carpet glue for a more reliable and long-lasting tile installation.
• Various methods can be used to remove carpet glue, including scraping, grinding, or using chemical strippers. It is important to follow manufacturer guidelines and safety precautions when using chemical strippers.

5. Consult with Professionals

• If you are unsure about whether to apply thinset over carpet glue or remove it, it is best to consult with professionals, such as flooring contractors or tile installers. They have the expertise to assess the condition of the existing surface and provide guidance on the most suitable approach.

While it is generally advised to remove carpet glue before applying thinset for tile installations, it may be possible to apply thinset directly over carpet glue in certain exceptional circumstances. However, it is crucial to perform a test area and consult with professionals to ensure a successful and durable tile installation.