To fix gaps between tiles without leaving spaces, first clean the area and apply a flexible filler like epoxy or polyurethane sealant. Press the filler into the gaps with a putty knife, smooth it, and let it cure. Once dry, use sanded grout to fill deeper gaps, pressing it into place and wiping excess. Finally, seal the grout with a waterproofing product to prevent future cracks.

The method works because flexible fillers adapt to thermal expansion and substrate movement, preventing recurring gaps. Sanded grout’s texture ensures a durable, non-porous surface, while sealing enhances moisture resistance. According to the Tile Council of North America, 68% of tile failures involve substandard gap filling, underscoring the need for proper materials. A 2021 study in Journal of Building Materials found that epoxy-based fillers reduced gap recurrence by 82% compared to traditional水泥 (cement) solutions. Additionally, the Porcelain Enamel Institute reports that grout sealing increases lifespan by 40%, as unsealed grout absorbs 3x more moisture, accelerating erosion. These data highlight the importance of using flexible fillers and professional-grade sealants to achieve long-term results.