Does all old thinset need to be removed?

Unfortunately, you can’t simply reapply thinset on top of old thinset.   Having any remnants of the old thinset still on the floor makes new floor installation nearly impossible.

When it comes to renovating or updating your home, removing old tile flooring is often a necessary step. However, one common question that arises during this process is whether all of the old thinset adhesive needs to be removed along with the tiles. Let’s look into this topic to understand the considerations involved.

Understanding Thinset Adhesive

Thinset is an adhesive, it is a cement-based bonding material used to attach tiles to surfaces such as concrete, plywood, or cement backer board. Over time, thinset can harden and bond firmly to both the tile and the substrate (an underlying substance or layer.) When removing old tile flooring, the thinset may remain stuck to the substrate even after the tiles have been removed.

The Importance of Removing Old Thinset

Dustlees tile removal
Uneven floors will not save time or money

While it may be tempting to leave the old thinset in place and simply install new tiles over it, this approach is not recommended for several reasons:

  1. Surface Irregularities: Old thinset can create an uneven surface, making it difficult to achieve a smooth and level tile installation. This can lead to problems such as cracked or uneven tiles.
  2. Adhesion Issues: New thinset may not bond properly to old, hardened thinset. This can compromise the integrity of the tile installation and increase the risk of tiles becoming loose or dislodged over time.
  3. Height Differential: The thickness of the old thinset adds to the overall height of the floor. Installing new tiles directly over the old thinset can result in height differentials between adjacent areas, transitions, or doorways, which can be unsightly and pose a tripping hazard.

Methods for Removing Old Thinset

Removing old thinset can be a labor-intensive process, but it is essential for ensuring a successful tile installation. Smoother flatters floors make for beautiful, longer lasting flooring.  Here are some common methods for removing old thinset:

  • Scraping: Using a handheld scraper or chisel to manually scrape away the old thinset from the substrate.
  • Grinding: Using a floor grinder with a diamond grinding wheel to grind away the old thinset.
  • Chemical Removers: Applying a commercial adhesive remover to soften the old thinset, making it easier to scrape or grind away.

Conclusion

In conclusion, while it may be possible to leave old thinset in place when removing tile flooring, it is generally not recommended due to potential issues with surface irregularities, adhesion, and height differentials. Taking the time to properly remove old thinset ensures a smooth and successful tile installation, minimizing the risk of future problems. Consider consulting with a professional contractor for guidance on the best approach for your specific project.

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