Survey cracks, parapets, penetrations. Positive: re‑waterproof with 2K PU or Polyurea; SBS under protection for simple roofs. Negative backup: PU injection from below where inaccessible. Always reinforce upstands and joints; pond test 72 hr.
LQ-ROOF
Survey cracks, parapets, penetrations → grind/clean → provide 20×20 mm fillets at upstands → apply 2K PU or Polyurea to spec DFT; reinforce corners with geotextile → terminate into chases; add protection where needed → 72‑hr pond test.
DFT log per pass; adhesion pull‑off ≥1.0 MPa; pond test 72 hr pass; holiday detection for spray systems on representative areas.
Includes terraces and roof slabs; parapets, upstands, penetrations, expansion joints consolidated into Roof Leakages canonical record.
Summary
Roof leakages arise from slab or screed cracks, aged or punctured membranes, weak parapet and expansion joint detailing, and unreinforced penetrations. Prefer positive-side re-waterproofing when accessible; use negative-side injection only when the roof surface cannot be accessed.
Symptoms
- Damp ceiling below the roof after rains
- Local seepage near parapets, joints, or pipe bases
- Blisters, cracks, exposed reinforcement on roof surface
Probable causes
- Thermal movement and joint detailing failures
- UV degradation and aging of past coatings
- Poor terminations at parapets and edges
- Penetrations not reinforced or sealed
Standard remedy overview
1) Positive-side re-waterproofing (preferred)
- Repair cracks, provide 20×20 mm fillets at upstands
- Prime and apply specified membrane to target DFT
- Reinforce corners, joints, and details; terminate into chases; provide wear or protection layers as needed
2) Negative-side contingency (when top access is impossible)
- Map leakage lines; install NRVs at 300–500 mm centers from below
- Inject suitable grout (PU hydrophilic for running leaks; vinyl acrylate for micro-porosity)
- Plan follow-up positive-side waterproofing when accessible
Recommended technologies
- 2K PU (hand) and spray PU for large roofs
- Polyurea for heavy-duty, fast-turnaround work
- SBS sheets for simple geometries (under screed/tiles)
- Injection grouts for negative-side cut-off
Quick SOP
1) Survey cracks, joints, penetrations; conduct hose test if needed
2) Prepare substrate; provide fillets
3) Prime and apply system to DFT; reinforce details
4) Terminate into chases; install protection/wear coat
5) 72‑hour pond test where applicable
Decision guide
- Large exposed roofs needing fast return → spray PU or polyurea
- Simple roofs under protection → SBS sheets
- Inaccessible top surface → injection cut-off from underside, then plan positive-side system later
Acceptance criteria
Video Masterclass
Masterclass: Roof Leakages — Coming soon
Disclaimer
Conix is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.