Waterproofing and Damp-Proofing Inspection

In accordance with EN 13967 (damp-proof sheets), EN 13969 (bitumen damp-proof courses) and UNI 11470 (design and installation of waterproofing systems). NTC 2018 Chapter 11 requires documented material traceability. The substrate must comply with surface regularity and moisture content limits specified in UNI 8178 (flat roof waterproofing).

1. Verify that the concrete substrate has cured for the minimum period specified by the designer (typically 28 days) and test residual moisture content with a capacitance moisture meter — values should be below 4% by mass

2. Inspect the substrate surface for cracks, honeycombing, sharp protrusions and loose material; all defects must be repaired before membrane application

3. Check that fillets (sgusce) are formed at wall-to-floor junctions at 45 degrees, minimum 50 mm leg, in accordance with UNI 11470

4. Verify that falls are correct (minimum 1% for flat roofs per UNI 11470) using a spirit level and laser level

5. Confirm that the substrate has been primed with the appropriate bituminous primer and that the primer has fully dried before membrane installation

- Membrane applied to substrate with excessive residual moisture, leading to blistering and delamination

- Missing or poorly formed fillets at changes of plane, creating stress points in the membrane

- Insufficient falls causing standing water (ponding) on flat roofs

- Substrate cracks not treated with reinforcement strips before membrane application

- Primer omitted or not allowed to dry, reducing membrane adhesion

In accordance with EN 13707 (reinforced bitumen sheets for roof waterproofing), EN 13969 (bitumen damp-proof courses), EN 13956 (plastic and rubber sheets) and UNI 11470. NTC 2018 Chapter 11.1 requires that all construction materials are accompanied by a declaration of performance (DoP) and CE marking. Materials must comply with the specifications in the designer's waterproofing project.

1. Check delivery documents and CE marking labels for each roll of membrane, verifying product type, thickness, reinforcement type and declared performance values

2. Cross-reference the delivered membrane product against the designer's specification and verify compatibility with the substrate and any insulation layers

3. Verify the membrane thickness using a calibrated gauge — typical minimum values are 4 mm for single-layer bituminous systems and 1.5 mm for synthetic (PVC/TPO) per UNI 11470

4. Check storage conditions on site: rolls must be stored upright, protected from rain and direct sunlight, and at temperatures above 5 °C for bituminous membranes

5. Confirm the membrane has the required certifications for the specific application (e.g., root resistance per EN 13948 for green roofs, fire classification per EN 13501-5 for roofs)

- Membrane product substituted on site without designer approval, resulting in incompatible system

- Missing or illegible CE marking and DoP documentation

- Membrane stored flat or exposed to weather, causing deformation or surface degradation

- Thickness below minimum specification due to manufacturing tolerances not checked

In accordance with EN 13707 and UNI 11470, membranes must be applied with the method specified by the manufacturer (torch-applied, self-adhesive or mechanically fixed). Lap widths must comply with UNI 11470 (minimum 80 mm side laps and 120 mm end laps for bituminous membranes). NTC 2018 requires execution in accordance with the approved project documents.

1. Observe the application process: for torch-applied membranes, verify that the bitumen on the underside is uniformly melted (visible flow of bitumen at the roll edge) without overheating or burning the reinforcement

2. Measure side lap widths with a tape measure — minimum 80 mm for bituminous and as specified by manufacturer for synthetic membranes (typically 50–100 mm)

3. Measure end lap widths — minimum 120 mm for bituminous membranes; verify that end laps are staggered by at least 300 mm between adjacent sheets

4. Check that laps are fully sealed by pressing along the joint and verifying continuous bitumen squeeze-out or weld bead for synthetic membranes

5. Verify that the membrane is applied in the correct direction (from the lowest point upward) so that laps shed water correctly

6. For mechanically fixed systems, check fastener type, spacing and pull-out resistance in accordance with ETAG 006 / EN 16002

- Insufficient heating of bituminous membrane resulting in poor adhesion and open laps

- Lap widths below minimum, particularly at corners and complex details

- End laps aligned between adjacent sheets, creating a four-layer intersection point prone to leakage

- Overheating of membrane destroying the reinforcement and reducing durability

- Membrane applied in wrong direction with laps facing into water flow

In accordance with UNI 11470 and EN 13707 Annex A, all penetrations (pipes, drains, vents) and junctions (parapets, walls, expansion joints) must be waterproofed with purpose-made details. Upstands must extend a minimum of 150 mm above the finished surface level (UNI 11470 Section 7). D.M. 236/1989 requires accessible roof terraces to have waterproof thresholds.

1. Measure upstand heights at parapets and abutments — minimum 150 mm above the finished surface or 250 mm in areas subject to snow accumulation per UNI 11470

2. Inspect pipe penetrations for properly formed collars with clamping rings and verify that the membrane is dressed into the collar without gaps

3. Check drain details: the membrane must be dressed into the drain body with a continuous bond, and the drain flange must be clamped over the membrane

4. Verify expansion joint details for the presence of a flexible loop or bellows in the membrane to accommodate movement

5. Inspect corner details (internal and external) for additional reinforcement layers — prefabricated corner pieces or additional membrane strips are required

- Upstand height below 150 mm, particularly where paving or gravel is installed on top of the membrane

- Pipe collars not clamped, allowing water ingress along the pipe surface

- Drain connections poorly sealed, with membrane not fully bonded to the drain flange

- Missing reinforcement at internal corners, leading to cracking under thermal and structural movement

- Expansion joints bridged rigidly without a flexible loop, causing membrane tearing

In accordance with UNI 11470 Section 9 and project specifications, flat roofs and wet areas must be flood tested (prova di tenuta) before protection layers or finishes are applied. The test duration is typically 24–48 hours with a water depth of 50–100 mm. For below-ground waterproofing, EN 13967 and NTC 2018 require documented verification of watertightness.

1. Verify that all drains are temporarily sealed and the area is flooded to the specified depth (typically 50 mm minimum) — record the water level at the start with a marker or gauge

2. Monitor the water level over the test period (minimum 24 hours for roofs, 48 hours for balconies and terraces per UNI 11470) and check for any drop in level

3. Inspect the underside of the waterproofed area (soffit) for any signs of water staining, dripping or damp patches during and after the test

4. If leaks are detected, mark the location on both the upper surface and the soffit, drain the area, repair the membrane and re-test

5. Document the flood test with dated photographs, water depth measurements, duration and a signed acceptance report

- Flood test omitted due to time pressure, with leaks only discovered after finishes are installed

- Insufficient test duration — test terminated before 24 hours, missing slow leaks

- Drains not properly sealed during test, giving a false negative result

- Repairs made but not re-tested to confirm effectiveness

- No photographic or written record of the test for the building file

In accordance with UNI 11470 and EN 13252 (geotextiles), the waterproofing membrane must be protected from mechanical damage and UV degradation by appropriate protection and drainage layers. For below-ground applications, EN 13967 requires a drainage layer and protection board. D.Lgs. 192/2005 and UNI/TS 11300 require consideration of the complete roof build-up for thermal performance.

1. Verify that the protection layer type matches the specification — options include geotextile separation layer (minimum 300 g/m² per UNI 11470), extruded polystyrene (XPS) boards for inverted roofs, or screed for accessible terraces

2. Check that drainage boards or granular drainage layers are installed with the correct orientation (dimples facing the membrane or outward as specified) and that filter fabric is placed on top

3. Confirm that drainage channels and outlets are unobstructed and connected to the rainwater disposal system

4. For green roof systems, verify that the root barrier, drainage layer, filter sheet and growing medium comply with UNI 11235 (green roof standard)

5. Inspect the transition between the protected membrane area and any exposed upstand areas — exposed membrane must be UV-resistant or protected with metal flashing

- Protection layer omitted, exposing the membrane to mechanical damage during subsequent works

- Drainage board installed upside down, preventing water flow to drains

- Filter fabric missing, allowing fine particles to clog the drainage layer

- Incompatible materials placed in direct contact with the membrane (e.g., uncured concrete on PVC membranes)