Do I Have to Remove All the Adhesive From a Carpet on Concrete Before Tiling?

After years--and sometimes even decades--a home's carpet is in need of serious upgrade.

Scraping

Carpet adhesive resists a good tile bond.Carpet adhesive resists a good tile bond.
Perhaps you have already removed ugly, stained carpeting and are just about to head out to the tile warehouse to select floor tile. If some of the carpet adhesive is still stubbornly clinging to the concrete floor, you may be wondering just how much of it needs to go before installing your shiny new tile. Carpet adhesive is gummy and sticky but easier to scrape away than you might think.

The key to installing tile over a formerly carpeted area is to remove as much of the adhesive as possible. Typically, carpet installers install carpet padding with thin, easily removed zigzag adhesive lines. Use a common floor scraper to scrape away the glue. Floor scrapers are made for removing drywall mud, mortar, paint and other materials; the tool perfectly suits adhesive removal. Target the thick, zigzag adhesive lines, doing your best to pry under the adhesive with the scraper's blade. Scrape the adhesive until you expose the gritty concrete surface beneath.

Chemical Adhesive Removers

Don't use a chemical stripper to remove the adhesive. Thin-set mortar manufacturers explicitly note avoiding chemical adhesive removers, which contain chemicals that melt carpet adhesive, causing it to permeate deep into the concrete's surface. In worst-case scenarios, this may prevent a tile bond and keep you from being able to tile the floor at all.

Testing for a Good Bond

Thin-set mortar manufacturers recommend checking a concrete substrate's permeability by applying water to it. Sprinkle water on a test area. If it soaks in, chances are the substrate is ready for tile because adhesive can bond. If the water beads up and sits on the concrete, wipe it away and scrape some more. Repeat the water test until the entire floor (or stubborn adhesive areas) accepts water. Allow time for the floor to dry before installing tile.

Additional Guidelines

Use special flex-blend polymer-modified thin-set mortar for tiling over preexisting carpet. Don't use a non-latex, basic thin-set mortar. Spread an anti-crack membrane over any visible substrates cracks. Before proceeding, make sure the installation surface area is free of dust and sediment. As carpet removal is a dusty job, wear a particulate dust mask and ventilate the work area.

About the Author

Residing in San Diego, Calif., Tim Daniel is a professional writer specializing in politics. His work has appeared at both the Daily Caller and Pajamas Media. With more than 20 years of experience in the field of construction, Daniel also specializes in writing about tile, stone and construction management. He is pursuing a bachelor's degree in communications.