Waterproofing Inspection

Per DTU 14.1 and DTU 43.1, the substrate must be clean, dry, smooth, and free from defects before waterproofing application. Surface moisture content must not exceed the limits specified for the chosen membrane system. EN 13967 specifies substrate requirements for moisture barrier installations.

1. Verify that the concrete substrate has achieved the minimum age and strength specified in DTU 14.1 (typically 28 days minimum cure)

2. Measure surface moisture content using a calibrated moisture meter — must not exceed 5% for bituminous membranes per DTU 43.1

3. Inspect the substrate for cracks, honeycombing, or surface irregularities exceeding 5 mm under a 2 m straightedge

4. Check that all penetrations (pipes, ducts) are properly formed with suitable upstands or sleeves

5. Confirm that primer or bonding agent has been applied where required by the membrane manufacturer

- Substrate too wet at time of membrane application, causing adhesion failure

- Surface irregularities puncturing the membrane under hydrostatic pressure

- Missing or inadequate treatment around penetrations and pipe sleeves

- Insufficient curing time of the concrete substrate before membrane installation

DTU 14.1 and DTU 43.1 specify minimum overlap widths, bonding methods, and installation sequences for waterproofing membranes. EN 14967 defines performance requirements for flexible sheet membranes. All laps must be fully sealed with no voids, wrinkles, or fish-mouths.

1. Verify that membrane type and thickness match the specification and are certified to EN 14967 or hold an Avis Technique

2. Measure overlap widths at sheet joints — minimum 100 mm for side laps and 150 mm for end laps per DTU 43.1

3. Check that membranes are fully bonded or mechanically fixed as specified, with no air pockets or wrinkles

4. Inspect all seam welds using a probe or seam tester to confirm complete fusion

5. Verify correct orientation and layering sequence for multi-layer systems per DTU 43.1

- Insufficient overlap width at sheet joints leading to water ingress

- Fish-mouths or wrinkles at laps causing localised weakness

- Incomplete torch welding or adhesive bonding leaving unbonded zones

- Wrong membrane orientation or incorrect layering sequence in multi-ply systems

Per DTU 14.1 and DTU 43.1, all junctions between waterproofing membranes and building elements (walls, pipes, drains) must be sealed with dedicated detail components. Upstand heights, corner treatments, and collar details must comply with the DTU minimum dimensions.

1. Verify that upstand heights at wall-to-floor junctions meet the DTU 14.1 minimum of 150 mm above finished floor level

2. Inspect pipe penetrations for correctly installed prefabricated collars or clamping flanges with compression seals

3. Check internal and external corner details for reinforcement strips applied in accordance with DTU 43.1

4. Confirm that expansion joints are treated with flexible bellows or loop details per the membrane manufacturer's instructions

5. Verify that drainage outlets are recessed and the membrane is dressed into the outlet body with a clamping ring

- Upstands too low, allowing water to bypass the membrane at wall-floor junctions

- Pipe collars not clamped or sealed, creating a direct water path

- Missing reinforcement at internal corners leading to membrane cracking

- Expansion joint details too rigid, causing membrane tears during thermal movement

- Drain connections not watertight due to missing clamping rings

DTU 14.1 requires that below-grade waterproofing be protected from mechanical damage by a protection board or geotextile drainage layer. DTU 43.1 specifies protection layers for roof membranes including gravel ballast, paving, or green roof substrates. EN 13252 covers geotextile drainage composites.

1. Verify that a protection board (minimum 4 mm thickness) or drainage geocomposite is installed over the below-grade membrane per DTU 14.1

2. Check that the drainage layer directs water to a collector drain at the base of the wall

3. For flat roofs, confirm that gravel ballast is minimum 50 mm deep and of the correct grading per DTU 43.1

4. Inspect that protection layers are continuous with no gaps that would expose the membrane to damage during backfill

- Missing or damaged protection board allowing backfill materials to puncture the membrane

- Drainage layer installed upside down, blocking water flow instead of channelling it

- Insufficient gravel ballast depth causing wind uplift of the membrane on flat roofs

- No collector drain at the base, allowing hydrostatic pressure to build against the membrane

DTU 14.1 and DTU 43.1 require flood testing or spray testing of completed waterproofing systems before concealment. Flat roofs must be flood-tested to a minimum depth of 50 mm for 48 hours per DTU 43.1. Below-grade systems must be inspected before backfill.

1. For flat roofs, verify that flood testing has been carried out at minimum 50 mm depth maintained for 48 hours per DTU 43.1

2. For below-grade works, confirm that the entire membrane system has been inspected and documented before backfilling per DTU 14.1

3. Review test reports for any leaks detected and confirm that all repairs have been completed and re-tested

4. Use infrared thermography to identify trapped moisture or cold bridges indicating membrane failure

5. Check that all test results are recorded in the inspection log with date, duration, and outcome

- Flood test not maintained for the full 48-hour duration, missing slow leaks

- Below-grade membrane backfilled before inspection, concealing defects

- Leak repairs not re-tested after completion

- Missing or incomplete test documentation

Per DTU 14.1 and DTU 43.1, the waterproofing contractor must provide complete as-built documentation including membrane product certificates, test reports, and warranty conditions. French decennial liability (garantie decennale) applies to waterproofing as it is considered a structural element under French building law.

1. Verify that the waterproofing contractor holds valid decennial insurance (assurance decennale) covering the installed system

2. Confirm that all membrane product certificates and Avis Technique references are included in the handover file (DOE — Dossier des Ouvrages Executés)

3. Check that as-built drawings accurately show membrane layout, detail locations, and penetration treatments

4. Review warranty terms for duration (typically 10 years under garantie decennale) and any exclusions or maintenance conditions

- Contractor decennial insurance expired or not covering the specific waterproofing system installed

- Missing Avis Technique documentation for the membrane products used

- As-built drawings not updated to reflect changes made during construction

- Warranty voided by failure to follow specified maintenance procedures