Incorrect Install of EPDM around window Openings
The EPDM around the window opening is poorly formed and inadequately bonded, with loose folds, creasing, irregular joints, exposed insulation and apparent gaps at critical interfaces. The installation does not demonstrate a continuous, durable air and weather seal and may allow moisture and air ingress. The affected detail should be opened, inspected and fully reworked to the approved design and manufacturer’s instructions before being concealed; fire-stopping and cavity-barrier continuity must also be verified.
- NCQLE reference
- NCQLE-2026-00002
- Quality topic
- Defects and corrective action
- Lesson type
- Failure
- Evidence rating
- Experience
- Published
- 31 July 2026
- Last reviewed
- 31 July 2026
Evidence basis: Supported by relevant professional experience. This learning is provided for professional consideration and does not replace project-specific competent advice, statutory duties or contractual requirements.
Context
This was an Brand new install of External Hardie Planks cladding and new Window and door installs on a Penthouse Flat
The transferable lesson
EPDM around window openings must be installed strictly to the approved design and manufacturer’s instructions, with properly prepared substrates, fully bonded membranes, correctly formed corners and continuous sealed joints. Window interfaces should be treated as a formal inspection hold point, with the EPDM, insulation, fire-stopping and cavity barriers checked and photographed before concealment. Poor workmanship must be rejected and corrected before façade works proceed.
Recommended action
Agree the window-interface detail before installation and provide installers with manufacturer-approved drawings and training. Complete a benchmark installation for approval, confirming substrate preparation, compatible adhesives, minimum laps, corner formation and continuous sealing. Introduce a mandatory inspection hold point before concealment, supported by photographs of the EPDM, insulation, fire-stopping and cavity barriers. Reject and formally record loose, creased, damaged or incompletely bonded membranes, requiring full corrective work and reinspection.
Limitations and application
The findings are based on visual inspection of the accessible installation only. The photograph cannot confirm concealed membrane laps, adhesive coverage, fire-stopping or cavity-barrier continuity. Final acceptance must be assessed against the approved project details, EPDM manufacturer’s instructions and product-specific limitations, including substrate compatibility, temperature and weather conditions. Intrusive inspection or specialist review may be required to determine the full extent of the defect.