Waterproofing and Moisture Protection

EN 13967 and CTE DB-HS1 Section 2.1 require that the substrate receiving waterproofing membranes be clean, dry, smooth, and free from projections or voids. The surface must have adequate falls (minimum 1% for flat roofs per CTE DB-HS1) and be structurally sound to receive the membrane system.

1. Verify the substrate surface is free from dust, loose particles, oils, and contaminants

2. Measure surface moisture content with a pin-type meter — maximum values per membrane manufacturer specifications and CTE DB-HS1

3. Check surface regularity with a 2 m straightedge — deviations must not exceed 5 mm per UNE 104400

4. Confirm that all required falls and drainage slopes are achieved (minimum 1% for flat roofs per CTE DB-HS1)

5. Verify that internal corners have fillets and external corners are rounded to prevent membrane stress

- Substrate too wet at time of membrane application leading to blistering

- Surface irregularities causing membrane bridging and puncture risk

- Missing or inadequate fillets at internal corners

- Insufficient drainage falls causing ponding water

EN 13707 (reinforced bitumen sheets), EN 13967 (plastic/rubber sheets), and CTE DB-HS1 require that waterproofing membranes meet specified performance characteristics including tensile strength, elongation at break, and resistance to water penetration per EN 1928. Materials must carry CE marking and a Declaration of Performance (DoP).

1. Verify membrane product has CE marking and the Declaration of Performance (DoP) matches the specification

2. Check that the membrane type, thickness, and reinforcement match the design requirements per CTE DB-HS1

3. Confirm material has been stored correctly — rolls stored upright, protected from UV and moisture per manufacturer instructions

4. Review test certificates for watertightness (EN 1928), tensile strength, and elongation at break

5. Verify membrane compatibility with adjacent materials (primers, adhesives, insulation) per UNE 104400

- Membrane product substituted without design approval

- Materials stored flat or exposed to sun causing deformation

- Missing or expired CE marking documentation

- Incompatible primer or adhesive used with membrane type

CTE DB-HS1 and UNE 104400 require primers to be applied to substrates before bonded membrane installation to ensure adequate adhesion. The primer type must be compatible with both the substrate and the membrane system. Application rates and drying times must comply with manufacturer specifications and EN 13969.

1. Verify correct primer type is used for the substrate and membrane combination per manufacturer data sheet

2. Check that primer is applied uniformly at the specified coverage rate (typically 0.3-0.5 l/m2 for bituminous primers)

3. Confirm primer has fully dried/cured before membrane application — touch-dry test and minimum waiting time per manufacturer

4. Verify primer application extends to all areas receiving membrane including upstands and details

5. Check ambient temperature is within specified range for primer application (typically 5-35 C)

- Primer omitted from vertical surfaces and detail areas

- Insufficient drying time before membrane application causing poor adhesion

- Wrong primer type for substrate material

- Application in temperatures outside specified range

EN 13707 and CTE DB-HS1 Section 2.4 specify minimum lap widths (typically 100 mm side laps, 150 mm end laps for bituminous membranes) and installation methods. UNE 104400 details torch-applied, self-adhesive, and mechanically fixed installation procedures. All laps must be sealed to ensure continuous waterproof layer.

1. Verify membrane is laid in the correct direction — perpendicular to the fall line with laps facing down-slope

2. Measure lap widths at side joints (minimum 80-100 mm) and end joints (minimum 150 mm) per CTE DB-HS1

3. Check that torch-applied laps show uniform bitumen squeeze-out (2-5 mm bead) indicating full bonding

4. Verify membrane is fully bonded or mechanically fixed as specified — no air pockets or unbonded areas

5. Confirm that membrane is not overstretched during application, which reduces thickness and performance

6. Inspect all T-joints (three-layer intersections) for proper sealing

- Lap widths below minimum requirements causing water ingress paths

- Insufficient torch heat resulting in unbonded laps

- Overheating bituminous membranes destroying reinforcement

- Air trapped beneath fully bonded membranes causing blisters

- T-joints inadequately sealed

CTE DB-HS1 Section 2.4 and UNE 104400 require all penetrations, upstands, outlets, and movement joints to be detailed with additional membrane reinforcement. Upstands must extend a minimum of 200 mm above the finished surface level. Pre-formed collars or boots must be used for pipe penetrations per EN 13967.

1. Verify upstand heights — minimum 200 mm above finished paving or gravel level per CTE DB-HS1

2. Check all pipe penetrations have pre-formed collars or formed boots fully bonded to the membrane

3. Inspect movement joint details for correct flexible treatment allowing differential movement

4. Verify internal and external corner reinforcement strips are installed with minimum 150 mm overlap each side

5. Check that membrane terminations are mechanically fixed and sealed with appropriate sealant

- Upstand height less than 200 mm after paving or ballast is installed

- Pipe penetrations sealed with mastic only instead of proper collar detail

- Movement joints treated as rigid causing membrane failure

- Corner reinforcement strips omitted or insufficiently lapped

CTE DB-HS1 Section 2.2 requires drainage layers for below-grade waterproofing and inverted roofs. Protection layers (geotextile, drainage boards) must be installed to prevent mechanical damage to membranes per EN 13252 (geotextiles) and EN 13967. Drainage systems must connect to the building's drainage network per CTE DB-HS5.

1. Verify drainage board or dimpled membrane is installed with dimples facing the waterproofing membrane per manufacturer instructions

2. Check that a separation geotextile is placed over the drainage layer to prevent clogging per EN 13252

3. Confirm drainage layer connects to perimeter drains and ultimately to the storm water system per CTE DB-HS5

4. Verify protection board or layer is installed before backfilling or paving over the membrane

5. Check that filter fabric overlaps are minimum 150 mm and secured against displacement

- Drainage board installed with dimples facing wrong direction

- Missing geotextile filter allowing fine particles to clog drainage

- Drainage layer not connected to outlet, trapping water against membrane

- Protection layer omitted exposing membrane to mechanical damage during backfill

UNE 104400 and CTE DB-HS1 recommend flood testing (ponding test) for flat roofs and tanked areas to verify watertightness before protection layers are installed. The test involves flooding the area to a depth of 50-100 mm and maintaining the water level for a minimum of 24-48 hours. Any leaks must be repaired and retested.

1. Verify all outlets are temporarily sealed and the area is flooded to 50-100 mm depth

2. Mark the water level and maintain for minimum 24 hours (48 hours recommended by UNE 104400)

3. Inspect the underside of the structure for any signs of water penetration or damp patches

4. After draining, inspect the entire membrane surface for defects, blisters, or displaced laps

5. Confirm all identified defects are repaired and affected areas retested before protection layers are applied

6. Record test results with photographs, dates, and water levels in the quality documentation

- Flood test duration too short to reveal slow leaks

- Test conducted after protection layers installed, making leak location difficult

- Water level insufficient to test upstand details

- Defects repaired but area not retested to confirm fix

- Test results not documented for building handover records