Tiling Inspection

Per DTU 52.2, the substrate must meet specific flatness tolerances before tiling. For thin-bed adhesive fixing (typically 3-6 mm), substrate flatness must be within 5 mm under a 2 m straightedge and 2 mm under a 200 mm straightedge. The substrate must be clean, sound, and dry.

1. Measure substrate flatness using a 2 m straightedge — maximum 5 mm deviation for thin-bed fixing per DTU 52.2

2. Check localised flatness using a 200 mm straightedge — maximum 2 mm deviation per DTU 52.2

3. Verify that the substrate is free from dust, laitance, paint, or any contaminant that would reduce adhesion

4. Confirm that a suitable primer has been applied where required by the adhesive manufacturer

5. For plasterboard substrates, verify that the boards are type H1 and a SPEC membrane is applied in wet zones per Cahier CSTB 3529

- Substrate out of flatness tolerance, causing lippage between adjacent tiles

- Laitance or dust on screed surface reducing adhesive bond strength

- Missing primer on absorbent substrates leading to premature adhesive drying

- SPEC membrane omitted in wet areas, allowing moisture to penetrate the substrate

Per NF EN 14411 and DTU 52.2, tiles must meet the performance classification required for the application. In France, the Classement UPEC system rates tiles for Usure (wear), Poinconnement (indentation), Eau (water resistance), and agents Chimiques (chemical resistance). The tile UPEC rating must equal or exceed the room classification.

1. Verify that tile product data sheets confirm compliance with NF EN 14411 and display the correct group classification (BIa, BIb, BIIa, etc.)

2. Check that the tile UPEC rating (e.g. U3 P3 E2 C1) meets or exceeds the room UPEC classification per CSTB cahier

3. Confirm slip resistance classification — R rating for commercial areas, or Classement PC (pieds chaussés) for French barefoot/shod requirements

4. Verify that the tile water absorption rate is appropriate for the application (below 3% for external use per NF EN 14411)

5. Check tile batch consistency — all tiles should be from the same production batch to ensure colour and size uniformity

- Tile UPEC rating lower than the room classification, leading to premature wear

- Insufficient slip resistance for the intended use, creating a safety hazard

- Mixed tile batches causing visible colour and calibre variations

- High water absorption tiles used externally, causing frost damage

Per DTU 52.2 and NF EN 12004, tile adhesives must be selected for compatibility with the substrate, tile type, and environmental conditions. For tiles larger than 400 cm², double-buttering (encollage double) is required per DTU 52.2 to achieve minimum 65% contact area (internal) or 90% contact area (wet areas and external).

1. Verify that the adhesive classification (C1, C2, C2S1, etc. per NF EN 12004) is appropriate for the application

2. Check that double-buttering is applied for tiles exceeding 400 cm² and for all external or wet area installations per DTU 52.2

3. Remove a sample tile (if possible) to verify adhesive contact area — minimum 65% for dry internal, 90% for wet/external per DTU 52.2

4. Confirm adhesive bed thickness is within the manufacturer's specified range (typically 3-6 mm for thin-bed)

5. Verify that adhesive open time is respected — tiles must be placed while the adhesive is still tacky

- Single-buttering used on large format tiles, resulting in hollow spots and debonding

- Adhesive contact area below minimum requirements, causing tiles to sound hollow

- Adhesive skinning over before tile placement due to excessive open time

- Wrong adhesive class used for external or submerged applications

Per DTU 52.2, tiled surfaces must be level, with consistent joint widths and minimal lippage between adjacent tiles. Maximum permitted lippage is 1 mm for rectified tiles and 2 mm for non-rectified tiles. Joint widths must be minimum 2 mm for internal walls and 4 mm for external floors.

1. Measure lippage between adjacent tiles — maximum 1 mm for rectified tiles, 2 mm for non-rectified per DTU 52.2

2. Verify joint width consistency — minimum 2 mm internal walls, 3 mm internal floors, 4 mm external per DTU 52.2

3. Check overall surface flatness with a 2 m straightedge — maximum 3 mm deviation per DTU 52.2

4. Confirm that tile layout is symmetrical with cut tiles at perimeter edges being no smaller than half a tile width

5. Verify that floor tiles have adequate fall towards drains in wet areas — minimum 1% slope per DTU 52.2

- Excessive lippage between tiles creating trip hazards and an uneven appearance

- Inconsistent joint widths giving an unprofessional finish

- Narrow cut tiles at visible edges due to poor layout planning

- Insufficient fall to drains in shower areas causing ponding water

Per DTU 52.2 and NF EN 13888, grout must be fully compacted into all joints with no voids. Movement joints (joints de fractionnement) must be provided at maximum 60 m² intervals or 8 m linear in any direction for internal floors per DTU 52.2. Perimeter joints must be filled with flexible sealant, not grout.

1. Verify that grout type (CG or RG per NF EN 13888) is appropriate for the application — RG (epoxy) required for chemical exposure areas

2. Check that all joints are fully filled with grout compacted to full tile depth with no voids or pinholes

3. Confirm that movement joints are provided at maximum 60 m² areas or 8 m spacing per DTU 52.2

4. Verify that perimeter joints at walls, columns, and changes of substrate are filled with flexible sealant, not grout

5. Check that grout colour is consistent and joints are cleaned of excess grout residue

- Grout voids or pinholes allowing moisture penetration behind tiles

- Missing movement joints causing tile debonding and cracking at stress points

- Perimeter joints grouted instead of sealed with flexible sealant, causing cracking

- Grout haze left on tile surfaces due to inadequate cleaning during installation

Per DTU 52.2, a sounding test (sonnage) must be performed on completed tiling to detect hollow or debonded tiles. The test involves tapping each tile with a sounding hammer or hard object. A hollow sound indicates insufficient adhesive contact. Maximum acceptable hollow area is 15% for internal floors per DTU 52.2.

1. Tap each tile systematically with a sounding hammer, listening for hollow versus solid sounds

2. Mark any tiles producing a hollow sound for further investigation

3. Calculate the percentage of hollow tiles — must not exceed 15% for internal dry areas per DTU 52.2

4. For wet areas and external installations, no hollow tiles are acceptable (0% tolerance per DTU 52.2)

5. Where hollow tiles exceed limits, investigate whether re-fixing or replacement is required

- High percentage of hollow tiles due to insufficient adhesive coverage or single-buttering

- Hollow tiles concentrated near edges or corners where adhesive was not spread fully

- Hollow tiles in wet areas allowing water ingress and eventual debonding

- Tiles that initially sound solid becoming hollow over time due to adhesive failure

Per DTU 52.2 and Cahier du CSTB 3529, tiling in wet areas (douches, salles de bains) must incorporate a SPEC (Système de Protection à l'Eau sous Carrelage) waterproofing system. The SPEC membrane must cover all tiled surfaces in the splash zone and be dressed into drains and outlets. Tile adhesive and grout must be suitable for wet conditions.

1. Verify that a SPEC-certified waterproofing membrane has been applied to all walls and floors within the wet zone per Cahier CSTB 3529

2. Check that the SPEC membrane extends minimum 200 mm beyond the splash zone boundaries

3. Confirm that membrane reinforcing tape is applied at all internal corners, changes of plane, and around penetrations

4. Verify that drain and outlet connections are waterproof with the membrane dressed into the fitting body

5. Check that adhesive classification is minimum C2S1 for wet area wall tiling and C2 for wet area floor tiling per DTU 52.2

6. Confirm that grout in shower areas is waterproof type or epoxy (RG per NF EN 13888)

- SPEC membrane omitted or only partially applied in the wet zone

- Membrane not reinforced at corners, leading to cracking and water ingress

- Drain connections not sealed into the membrane system

- Standard grout used in showers instead of waterproof or epoxy grout

- Adhesive not suitable for prolonged wet conditions