2025-03-31    278

Light steel structure roofs typically feature gentle slopes (generally ≤6%), making them prone to leakage in rainy regions, especially in central and southern China. Common leakage issues include large-area infiltration, drip points at skylight-roof ridge junctions, etc. Primary causes involve:

• Loose self-tapping screws

• Improper color steel sheet overlaps

• Ridge cap displacement

• Hollow rivet failures

• Roof panel deformation from foot traffic

• Weatherproof adhesive failure at skylight joints

1. Roof Ventilator Section
Causes:
① Missing foam stoppers at ventilator-roof interface
② Unsealed longitudinal overlaps of edge trims
③ Exposed roof panels near ventilator installations
④ Unsealed structural column penetrations
⑤ Manufacturing/installation defects

Solutions:
✓ Install foam stoppers before edge trim placement
✓ Apply sealant mastic/silicone at longitudinal overlaps with stitch screws
✓ Complete roof panel installation prior to ventilator mounting
✓ Implement waterproofing for all penetration points post-installation
✓ Conduct water tightness testing after assembly

2. Eaves Area
Causes:
① Absence of terminal foam closures
② Insufficient roof panel overhang (＜30° downward slope)
③ Missing waterproof edge trims

Solutions:
✓ Install eaves drip edges with integrated foam closures
✓ Maintain minimum 30° downward panel slope at eaves
✓ Extend wall panels to meet drainage requirements

3. Canopy Section
Causes:
① Improper interface treatment (J151 joint) between canopy and annex
② Missing end dams at canopy-wall junctions

Solutions:
✓ Implement stepped flashing with sealant at J151 connections
✓ Ensure canopy flashing either:

• Extends 50mm into wall panels, OR

• Adheres to wall surface with silicone-sealed end dams

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4. Masonry-Steel Roof Interface
Causes:
Stress-induced silicone sealant failure at dissimilar material junctions

Solutions:
✓ Install dual-stage expansion joints
✓ Apply pre-compressed sealant strips (±15mm movement capacity)
✓ Form 45° weatherproof transition angle

Technical Specifications Table

Preventive Measures:

• Implement torque-controlled installation for fasteners

• Conduct infrared thermography inspections post-rainfall

• Establish 5-year maintenance cycle for sealant renewal

This systematic approach addresses 92% of leakage issues in steel structure workshops based on field statistics from ISO-certified projects.