Wall and Floor Tiling Inspection

In accordance with EN 12004 (adhesives for tiles), EN 14411 (ceramic tiles) and UNI 11493 Section 10. The substrate must be flat, clean, stable and free of contaminants. Maximum substrate flatness deviation is 2 mm under a 2 m straightedge for tiles up to 300 mm, and 1 mm for large-format tiles (over 600 mm) per UNI 11493. Screed must have cured for the minimum period (typically 1 mm per day up to 40 mm thickness).

1. Check substrate flatness using a 2 m straightedge — maximum deviation 2 mm for standard tiles, 1 mm for large-format tiles per UNI 11493; apply levelling compound if required

2. Test substrate moisture content with a carbide bomb (CM method) or electronic moisture meter — maximum 2% CM for cementitious screeds, 0.5% CM for anhydrite screeds before tiling

3. Verify substrate bond strength by scraping/tapping — the screed must be well bonded to the structural floor with no hollow areas

4. Check that the substrate has been primed with the appropriate primer for the adhesive system being used, especially on absorbent or dusty substrates

5. For tiling over plasterboard in wet areas, confirm that the board is Type H1 (moisture-resistant) and that a liquid-applied waterproof membrane has been applied per UNI 11493

- Tiling on a screed that has not fully dried, causing adhesive failure and tile debonding

- Substrate flatness not checked, resulting in lippage between tiles and uneven surfaces

- Missing waterproof membrane under tiles in shower areas, leading to moisture penetration into the wall structure

- Primer omitted on dusty or highly absorbent substrates, reducing adhesive bond strength

In accordance with EN 14411 (ceramic tiles — definitions, classification and marking), EN 12004 (adhesives — classification and requirements) and NTC 2018 Chapter 11. Tiles must carry CE marking and conform to the absorption class specified: Group BIa (porcelain, <0.5%) for exterior and wet areas, or as specified by the designer. Adhesive class must match the application — C2TE S1 minimum for large-format and exterior tiles per UNI 11493.

1. Verify CE marking and product data sheets for tile batches — check that the tile group (BIa, BIb, BIIa, etc.) matches the specification for each area

2. Confirm that all tiles in each area are from the same production batch (lotto di produzione) to ensure consistent colour and calibre

3. Check adhesive type and class against the specification — verify CE marking, pot life and open time stated on the bag match the working conditions

4. For exterior applications, verify that tiles have frost resistance (marked as frost-resistant per EN ISO 10545-12) and adhesive is class C2 minimum

5. Verify that grout type and colour match the specification — cementitious (CG) or reaction resin (RG) per EN 13888

- Tiles from different production batches mixed in the same area, causing visible colour variation

- Standard C1 adhesive used for large-format tiles or exterior applications instead of the required C2 S1/S2 deformable adhesive

- Tiles with high water absorption (Group BIII) used in exterior or wet areas, leading to frost damage or staining

- Adhesive mixed incorrectly (too wet or too dry), reducing bond strength

In accordance with EN 12004 and UNI 11493. Adhesive must be applied using the appropriate notched trowel size for the tile format. Minimum adhesive coverage: 65% for internal floor tiles, 80% for external tiles, wet areas and large-format tiles (>600 mm side length) per UNI 11493. Back-buttering is required for tiles over 600 mm side length.

1. Verify the notched trowel size matches the tile format — typically 6 mm for mosaics, 8 mm for tiles up to 300 mm, 10–12 mm for tiles 300–600 mm, and 12–15 mm for tiles over 600 mm

2. Periodically lift a freshly laid tile to check adhesive coverage — measure the percentage of tile back covered with adhesive; it must meet the minimum (65% internal, 80% external/wet)

3. For large-format tiles (>600 mm), verify that both the substrate and the tile back are combed with adhesive (double-buttering / doppia spalmatura)

4. Check that adhesive is applied within the open time stated by the manufacturer — test by touching the adhesive surface; if it skins over, it must be removed and reapplied

5. Verify that adhesive does not fill more than two-thirds of the joint width, leaving space for grout penetration

- Insufficient adhesive coverage causing hollow-sounding tiles (detectable by tapping) and eventual debonding

- Adhesive applied beyond its open time, resulting in a dry skin that prevents proper bonding

- Back-buttering omitted for large-format tiles, leaving voids under the tile centre

- Notched trowel too small for the tile format, producing insufficient adhesive bed thickness

- Adhesive squeezed into joints, preventing proper grout penetration and adhesion

In accordance with UNI 11493 and EN 14411. Joint width must be consistent and not less than 2 mm for rectified tiles or 3 mm for non-rectified tiles, unless the designer specifies otherwise. Maximum lippage (dislivello) between adjacent tiles: 1 mm for tiles up to 300 mm, and 2 mm for larger formats per UNI 11493. Levelling clips are recommended for large-format tiles.

1. Check joint width consistency using a calibrated spacer or feeler gauge — joints must be uniform across the installation and match the specified width

2. Measure lippage between adjacent tiles using a straightedge and feeler gauge — maximum 1 mm for tiles ≤300 mm, 2 mm for larger tiles per UNI 11493

3. Verify overall surface flatness with a 2 m straightedge — maximum deviation 2 mm for walls and 3 mm for floors per UNI 11493

4. Check that tile cuts at edges and around penetrations are clean and not chipped — cuts should be made with an appropriate tile cutter, not snapped

5. Verify the layout pattern matches the approved design — check symmetry, alignment of joints between walls and floors, and that cut tiles at room edges are of acceptable width (typically minimum half-tile)

- Excessive lippage between tiles, creating a trip hazard on floors and an unsightly finish on walls

- Inconsistent joint widths giving the installation an unprofessional appearance

- Very narrow cut tiles at room edges (slivers) due to poor layout planning

- Pattern misalignment between adjacent walls or between wall and floor tile joints

- Tiles not level in wet areas, causing water to pool instead of draining to the outlet

In accordance with UNI EN 13888 (grouts for tiles — requirements, evaluation of conformity, classification and designation) and UNI 11493. Grout type must match the application: cementitious grout (CG1/CG2) for standard internal use, improved cementitious grout (CG2 WA) for wet areas, and reaction resin grout (RG) for chemical exposure or hygiene-critical areas. Minimum joint width is 2 mm for rectified tiles and 3 mm for non-rectified tiles per UNI 11493. Perimeter joints and movement joints must be sealed with elastic sealant, never with rigid grout.

1. Verify grout type and class against the specification — check CE marking and that the grout class (CG1, CG2, CG2 WA, or RG per EN 13888) is suitable for the area of use

2. Check that joints are fully filled to a consistent depth — grout must fill a minimum of two-thirds of the tile thickness and be finished flush or slightly concave

3. Inspect for consistent grout colour across the installation — variations indicate inconsistent mixing or application timing

4. Verify that all perimeter joints, movement joints and joints at changes of plane are sealed with a flexible sealant compatible with the grout, not filled with rigid grout

5. In wet areas (showers, bathrooms), confirm that a waterproof grout (CG2 WA or RG) has been used and that joints are continuous with no gaps or pinholes

- Rigid grout used in perimeter and movement joints, leading to cracking as the building moves

- Grout mixed too wet, resulting in weak joints, colour variation and pinholes

- Grouting carried out before adhesive has cured, disturbing tile position and adhesive bond

- Grout residue (boiacca) not cleaned from the tile surface promptly, leaving a haze that is difficult to remove

- Insufficient joint filling leaving voids that admit moisture and weaken the joint

In accordance with D.M. 236/1989 (accessibility requirements — floors must be non-slip), EN 14411 and UNI EN 13748-1. Floor tiles in common areas, bathrooms, kitchens, ramps and external areas must have adequate slip resistance. D.M. 236/1989 requires a dynamic coefficient of friction (DCOF) ≥ 0.40 for level floors and ≥ 0.40 for ramps. Testing per DIN 51130 (R value) or CEN/TS 16165 (pendulum test) is commonly referenced in Italian specifications.

1. Verify that the tile product data sheet declares the slip resistance class — R9 minimum for internal dry areas, R10 or R11 for wet areas and external surfaces per the designer's specification

2. For critical areas (swimming pool surrounds, commercial kitchens, external ramps), perform or request a pendulum test (CEN/TS 16165) on the installed surface — minimum PTV 36 for low risk

3. Check that the tile surface finish installed matches the specification — polished tiles (lappato) generally have lower slip resistance than matt or structured finishes

4. Verify that accessible ramps are tiled with tiles having a minimum R11 classification and that tactile indicators are provided where required per D.M. 236/1989

5. Inspect drainage falls in wet areas — minimum 1% towards floor drains to prevent standing water, which reduces the effective slip resistance of any tile

- Polished porcelain tiles specified for wet areas or external surfaces without verifying slip resistance values

- Slip resistance class not documented in the project specification, making compliance verification impossible

- Drainage falls incorrect in showers and bathrooms, causing standing water and increased slip risk

- Tiles meeting dry slip resistance requirements but failing when wet — wet testing not performed

- Tactile paving omitted at ramps and level changes in public buildings