Framing Your Tile: Borders and Edging Ideas for a Clean Finish

When it comes to tiling over concrete, the process might seem straightforward. After all, concrete is solid, durable, and often smooth—an ideal base for laying tiles, right? Well, not so fast. One critical consideration frequently overlooked is whether or not you need to include an underlayment. Skipping this essential step can lead to costly issues down the road, such as cracked tiles, uneven surfaces, or moisture problems. This post will walk you through the role of an underlayment, when you truly need it, and the best types for your project. Whether you're a beginner DIYer or a seasoned home renovator, understanding this foundational step is crucial to getting professional results. What Is an Underlayment and Why Does It Matter? Before we dig deeper, let's clarify what an underlayment actually is. An underlayment is a thin layer of material placed between your subfloor (in this case, the concrete surface) and your tiles. Functions of an Underlayment Crack Prevention: Concrete can expand, contract, and even crack with changes in temperature or settling over time. An underlayment acts as a shock absorber, preventing these movements from transferring to your tiles. Moisture Barrier: Concrete is porous by nature and can trap moisture. Without a protective barrier, this moisture can seep into your tiles or adhesive, causing them to loosen or become damaged. Surface Leveling: An underlayment can help correct minor imperfections or unevenness in the concrete, ensuring a smooth surface for laying tiles. Soundproofing: Especially in multi-story buildings, certain types of underlayments can reduce sound transmission, making them a valuable addition for quieter spaces. Skipping the underlayment can seem tempting—after all, it’s an extra step. But as we’ll discuss below, its benefits often outweigh the time and cost savings of leaving it out. When Do You Need an Underlayment for Tile Over Concrete? The need for an underlayment depends largely on the condition of your concrete floor and the environment where the tiles will be installed. Here are the key scenarios where an underlayment is essential. 1. When the Concrete Is Cracked or Uneven Visible cracks or surface irregularities in your concrete floor are red flags that should not be ignored. These imperfections can easily transfer pressure to your tiles, resulting in cracks or uneven tiles over time. Solution: Opt for a crack isolation membrane, which is a type of underlayment specifically designed to absorb movement caused by cracks or shifts in the concrete. 2. When Installing Tiles in Moisture-Prone Areas If you’re tiling over concrete in areas exposed to moisture—such as bathrooms, basements, or kitchens—underlayment is non-negotiable. Concrete absorbs and retains moisture, which can lead to mold, mildew, and adhesive failure. Solution: A waterproof underlayment, such as a liquid-applied or sheet membrane, acts as a moisture barrier. 3. When Adding Heated Flooring Planning to install radiant heating beneath your tiles? An underlayment is often necessary to create a stable surface for the heating system while preventing heat loss through the concrete. Solution: Use an uncoupling membrane or a specialized underlayment designed to accommodate heat cables. 4. When Soundproofing Is Important For buildings with multiple levels, soundproofing underlayment can be a game-changer, reducing the noise caused by foot traffic or dropped objects. Solution: Rubber or foam underlayments are excellent choices for soundproofing. 5. When the Concrete Is Perfectly Smooth and Dry Even in the best-case scenario—a flawless, level, and dry concrete surface—you might still benefit from an underlayment to enhance adhesion and reduce long-term wear and tear. Types of Underlayment for Tiling Over Concrete Not all underlayments are created equal. Depending on your project’s specific needs, you’ll want to select the right type of underlayment to ensure the best results. 1. Crack Isolation Membranes Crack isolation membranes are designed to combat the movement of concrete cracks from transferring to the tiles above. These membranes are typically thin, flexible sheets that can be applied directly to the surface of the concrete. Best for: Floors prone to cracking or minor surface imperfections. Popular option: Schluter-DITRA. 2. Uncoupling Membranes Uncoupling membranes provide a layer of separation between the tiles and the concrete. This reduces the stress caused by expansion and contraction, preventing tile damage. Best for: Areas exposed to temperature variations or heavy traffic. Popular option: Schluter-DITRA and RedGard uncoupling mats. 3. Waterproof Membranes These membranes are a must for moisture-prone areas to create a barrier between the concrete and the tile adhesive. Waterproof membranes can either be sheet or liquid-applied. Best for: Bathrooms, basements, and other wet environments. Popular option: MAPEI AquaDefense or Kerdi Waterproof Membrane. 4. Foam or Rubber Underlayments These types of underlayments are ideal for reducing sound transmission and adding cushioning under your tiles. Note that they are less common for concrete compared to other subfloor materials. Best for: Soundproofing in multi-level buildings. Popular option: QuietWalk Cushion Underlayment. How to Install an Underlayment Over Concrete Follow these general steps to prepare your surface and install an underlayment before tiling over concrete. Step 1: Prepare the Concrete Surface Clean the surface thoroughly. Remove dirt, debris, oils, or previous adhesives. Fill any large cracks or chips with a concrete filler or patching compound. Sand any high spots to level the floor. Step 2: Measure and Cut the Underlayment Roll out or lay your underlayment sheets on the floor to measure. Use a sharp utility knife or scissors to cut the material to fit your space. Step 3: Secure the Underlayment Depending on the type, you may need to use adhesive, screws, or simply lay it flat. For sheet membranes, use thin-set mortar to adhere it to the concrete. Step 4: Seal the Edges Apply waterproof tape or additional membrane strips to seal the joints in moisture-prone areas. Step 5: Prepare for Tiling Once the underlayment is secure, you’re ready to begin laying your tiles with thin-set mortar. Invest in the Right Foundation for Tiling Success While it may be tempting to skip the underlayment when tiling over concrete, doing so can lead to unforeseen issues later on. From preventing cracks to managing moisture, underlayments are an essential step for a professional and long-lasting tile installation. By taking the time to assess your specific project needs and choosing the right underlayment, you can ensure your tiled floors not only look great but also stand the test of time. Do you have a tiling project in mind and want more expert advice? Explore our blog for additional tips or get in touch with our flooring specialists for personalized recommendations! We serve Austin, Round Rock, Cedar Park, Pflugerfille, West Lake Hills, Bee Cave, Manor, Sunset Valley, Manchaca, Buda, Hornsby Bend, Hudson Bend Tile contractors, Tile contractor, Bathroom remodel Austin, Tile installers Tile Installation Pros Austin Austin, TX 78744 512-312-7956 https://www.tileprosaustin.com