Domakihub How to Lay Large-Format Tiles: A Step-by-Step Guide
Get a flawless, professional finish on big-slab tiles — from substrate prep to final grouting.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 6 min read
Large-format tiles — anything above 60 x 60 cm — are increasingly popular in Greek homes, holiday rentals, and hotel lobbies because their minimal grout lines make spaces feel larger and easier to clean. The video above walks through the full process on camera, while this guide breaks each stage into clear, numbered steps with the technical detail you need to plan the job confidently. Whether you are tiling a new build screed in a villa on the Peloponnese or refreshing a bathroom in an Athens apartment, the principles are the same: a perfectly flat substrate, the right adhesive, and patient layout work before a single tile is set.
Why Large-Format Tiles Demand Extra Care
Standard 30 x 30 cm tiles are forgiving — small variations in substrate flatness disappear under a thicker bed of adhesive. Large-format tiles (60 x 120 cm, 80 x 80 cm, or the increasingly common 120 x 260 cm slabs) bridge across any hollow spots, causing them to rock under load and eventually crack. The industry tolerance for substrate flatness tightens to ±3 mm over a 2-metre straightedge for tiles over 60 cm on any side — compare this to the ±5 mm typically accepted for smaller tiles.
This flatness requirement is the main reason large-format tiling is borderline professional territory for DIYers. A confident, experienced DIYer can absolutely do it on a sound, newly poured screed; on an older Greek concrete floor with uneven high spots and previous tile adhesive residue, the prep work alone can justify bringing in a licensed tiler to avoid an expensive cracking failure later.
Permits, Professionals, and What You Can Do Yourself
In Greece, interior floor and wall tiling does not normally require a building permit — it is classified as regular maintenance (συνήθεις εργασίες συντήρησης). If your project involves breaking up a structural slab, installing underfloor heating, or waterproofing a wet room that is part of a major renovation, those elements may require a permit and a licensed civil or mechanical engineer to oversee the work. Always check with your local Πολεοδομία (planning office) for any project that goes beyond replacing like-for-like finishes.
For waterproofing in bathrooms and terraces — a critical requirement in Greece's climate — use a proper waterproofing membrane (liquid or sheet) applied by someone who knows the correct overlap at wall/floor junctions and drain collars. A tiler can do this, but a botched waterproof layer behind beautiful large-format tiles is an expensive failure. Confirm the installer has experience with the specific membrane system before you commit.
5 Steps to Lay Large-Format Tiles
- 1
Prepare and flatten the substrate
Check the entire surface with a long straightedge (at least 2 metres). Mark any high spots with a pencil and grind them down with an angle grinder fitted with a diamond cup wheel. Fill dips and hollows with a floor-levelling compound rated for tile use — brands such as Mapei Ultraplan or Weber floor are widely available in Greece. Allow the compound to cure fully (check the data sheet; typically 24 hours per 10 mm depth). Prime porous concrete before levelling compound to prevent rapid water loss. The finished surface must be clean, dry, structurally sound, and free of any movement, oil, or old adhesive release agents.
- 2
Plan your layout before mixing any adhesive
Find the centre of the room by snapping chalk lines between the midpoints of opposite walls. From that centre point, dry-lay a row of tiles along both axes without adhesive to see exactly where the cuts will fall at each wall. Aim for cut tiles at edges to be at least half a tile wide — anything narrower looks unbalanced and is mechanically weaker. On rectangular rooms that are not perfectly square (common in older Greek construction), you may need to offset the starting point slightly. Mark your final layout lines on the floor with a chalk line and confirm them with a large carpenter's square before proceeding.
- 3
Mix and apply the correct adhesive with full back-buttering
For tiles over 60 cm on any side, use a large-format, low-slip C2TE S1 or S2 classified adhesive — the classification confirms it has deformability to cope with minor thermal movement, which matters enormously on Greek terraces and ground-floor slabs that heat significantly in summer. Mix to a smooth, lump-free consistency. Apply adhesive to the floor using a large-notch trowel (10–12 mm notch) and also back-butter the tile itself with a thin skim coat, pulling a smooth layer across the entire tile back. This double-application technique is essential for large formats to achieve the minimum 95 % adhesive contact required under the tile — spot or ridge-only coverage causes hollow spots and cracks.
- 4
Set, level, and align each tile using a levelling clip system
Lower the tile carefully onto the adhesive bed at a slight angle and press it firmly into position without sliding. Use a rubber mallet and a large beating block (a piece of timber covered with rubber or foam) to tap the whole surface evenly — never tap just one corner. Insert tile levelling clips (strozzacroci system) at every joint, then lock the wedges with pliers or a dedicated gun. These ensure adjacent tiles are perfectly flush across their long edges, eliminating the dangerous lippage that causes a trip hazard and looks amateurish. Check level constantly with a spirit level across adjacent tiles. Allow adhesive to set before removing the clip bases (usually 24 hours).
- 5
Grout, seal, and protect movement joints
Remove clip bases and clean any adhesive from joints before grouting. For large-format tiles, use a high-quality polymer-modified grout — for joints under 3 mm an unsanded grout is appropriate; for wider joints use a sanded or epoxy grout. Mix to the manufacturer's ratio, apply with a rubber grout float at 45 degrees to the joint, and work in small sections. Clean excess with a damp sponge before it dries. Critically, do NOT grout movement joints — the perimeter joint at every wall, any expansion joint in the floor, and joints over structural beams must be filled with a flexible silicone sealant in a matching colour. In Greece's thermal environment, omitting movement joints is one of the most common causes of large-format tile failure within 2–3 years.
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FAQ
- What thickness of tile adhesive bed is acceptable under large-format tiles?
- Most C2TE adhesives are rated for a bed between 3 mm and 12 mm when used with back-buttering. Never attempt to level significant hollows with adhesive — it is not a levelling compound and thick beds increase the risk of shrinkage cracks. For hollows deeper than 6 mm, always use a proper levelling compound first and bring the substrate into tolerance before tiling.
- Can I lay large-format tiles over existing tiles in a Greek apartment?
- Technically possible but risky. The existing tiles must be completely sound (zero hollow tiles — check by tapping), the total floor build-up must not raise the floor enough to conflict with door thresholds or adjoining rooms, and the substrate beneath the old tiles must be able to carry the additional load. In older Athens apartment blocks with hollow-pot (πλακόπαρο) floor construction, adding heavy large-format stone or porcelain slab tiles over existing tiles can exceed the slab's design load. When in doubt, remove the old tiles and have a structural engineer assess the slab.
- How wide should grout joints be for large-format tiles?
- Most manufacturers of large-format porcelain tiles specify a minimum 2 mm joint to allow for the slight dimensional variation between tiles (calibrated tiles can go narrower; rectified tiles can go to 1.5 mm). For floor tiles in domestic or rental property, a 3–5 mm joint is practical — it is more forgiving during installation and easier to maintain. Avoid zero-joint or seamless layouts unless you are using perfectly rectified tiles on a perfectly flat substrate with professional equipment, as any slight lippage becomes immediately obvious.