10 common mistakes when laying tiles - and how to avoid them

Laying tile may look like a simple process at first glance—apply adhesive and set the tile. In practice, however, there are many details to consider. Even one mistake can be enough for tiles to become uneven, crack, or allow water to leak within a few months, requiring the work to be started again.

We have gathered the 10 most common mistakes and offer expert advice on how to avoid them.

1. Preparing the surface incorrectly

You cannot build a solid house on a weak foundation. In the same way, tiles cannot be laid on a dusty, damp or uneven floor.

• Mistake: Laying tiles on a dusty, damp or uneven floor (poured base).
• Result: The adhesive bonds to the dust rather than the floor. Over time, the tile becomes hollow-sounding and comes loose.
• Solution: The surface must be perfectly clean, dry and level. Always use a primer to bind the dust. If the floor is uneven, first use a self-levelling floor compound.

2. Ignoring grout joints (laying tiles without joints)

Some homeowners want a “seamless” look and ask for tiles to be laid without gaps.

• Mistake: Laying tiles edge-to-edge, without joints, in the hope of a better appearance.
• Result: As temperatures change, both the building and the tile itself “breathe” (expand and contract). Without space, the tiles press against one another and crack or buckle.
• Solution: Leave at least a 2–3 mm grout joint. This is essential for thermal expansion. Quality grout will also make these lines look attractive in the interior.

3. Choosing the wrong tile adhesive

Not all adhesives are the same. Adhesive intended for small ceramic wall tiles will not support heavy porcelain floor tiles.

• Mistake: Using inexpensive “universal” adhesive for large-format or porcelain tiles.
• Solution: Porcelain tile is heavy and does not absorb water, so it needs a reinforced, flexible adhesive. For large formats, use class C2TE S1 (for example, MAPEI Keraflex Maxi S1).

4. Applying adhesive unevenly

• Mistake: Applying adhesive in spots at the corners of the tile.
• Result: Voids remain beneath the tile. If a heavy object falls on that area or you step on it in a heel, the tile will break.
• Solution: Use a notched trowel and apply the adhesive in even ridges. For large tiles, use the “double application” (back-buttering) method—apply adhesive to both the floor and the back of the tile.

5. Soaking tiles in water

• Mistake: Soaking modern tiles in water.
• Reality: This method was necessary for Soviet-era clay tiles. Modern tiles and adhesives do not require it. On the contrary, excess moisture interferes with the adhesive’s performance.
• Solution: Lay them dry. Clean the back of a tile with a damp sponge only if it is dusty, but never wet it.

6. Levelling by eye

• Mistake: Working without a level and laser.
• Result: When you reach the centre of the room, the lines will be slanted and the pattern will shift.
• Solution: Use a laser for straight lines and always use a tile-levelling system (so-called clips and wedges). This system aligns tiles perfectly with one another and prevents lippage.

7. Ignoring grout quality

• Mistake: Using inexpensive grout in wet areas.
• Result: Water gets beneath the tile, and mould and fungus develop.
• Solution: Use hydrophobic (water-resistant) and anti-fungal grout (for example, MAPEI Ultracolor Plus).

8. Rushing the work

• Mistake: Walking on a wet floor.
• Result: Stepping on newly laid tile disrupts its level and deforms the surface. Grouting too early traps moisture beneath the tile, which can cause the grout to yellow or develop stains.
• Solution: Wait at least 24 hours from laying the tiles until grouting. Walking on them too early shifts the tiles out of level.

9. Poor-quality tools

• Mistake: Walking on a wet floor.
• Solution: Wait at least 24 hours from laying the tiles until grouting. Walking on them too early shifts the tiles out of level.

10. Working without a professional

• Mistake: Carrying out complex work (for example, large-format tiles or a herringbone layout) without prior experience.
• Solution: Laying tile requires practical skill and an experienced hand. If you are not confident, hire a professional. As an alternative, you can invite a tradesperson only as a consultant to begin the layout, then continue according to their instructions. In the end, this will save you money.

Frequently asked questions (FAQ)

What size notched trowel should I use for 60 × 60 cm tiles? — Use a 10 mm or 12 mm notched trowel at minimum. It is also advisable to use the “double application” method (apply a thin layer of adhesive to the back of the tile as well) so the adhesive fully covers the surface.

Can new tile be laid over old tile? — Yes, but only if the old tiles are firmly set and do not move. You must use a special primer (for example, quartz primer or “Betonokontakt”) and a high-quality flexible adhesive.

Why has the grout cracked? — Grout usually cracks if the adhesive underneath was not completely dry at the time of grouting, or if too much water was added to the grout mixture. It can also happen if the subfloor moves.