Roofing Installations
A successful roofing installation depends on proper material selection, exact pitch calculations, correct underlayment, and weather-resistant flashings.
Key Installation Steps
Substrate & Framing Preparation
Ensure trusses, rafters, or purlins are structurally sound, level, and spaced per engineering standards. Inspect for rot or warping before mounting decking or battens.
Underlayment & Moisture Barrier
Lay high-performance breathable roofing felt or synthetic underlayment starting from the eave upward. Overlap seams by at least 100 mm to ensure water sheds toward gutters.
Flashing & Valleys
Install corrosion-resistant metal flashings along valleys, sidewalls, chimneys, and ridge joints before fixing the primary roofing material.
Primary Roofing Application
Secure tiles, shingles, or metal sheeting (e.g., IBR or Corrugated profiles) using anti-corrosive fasteners fitted with weather-sealing EPDM washers. Maintain correct overlap tolerances based on roof pitch.
Ridge & Hip Sealing
Finish top ridges with dedicated capping and dry-ridge systems or mortar bedding, ensuring full resistance against wind-driven rain and thermal movement.
Essential Technical Specifications
| Metric / Parameter | Recommended Standard | Purpose |
| Minimum Pitch (Corrugated) | 10° (1:5.7 slope) | Prevents water back-up under metal seams |
| Minimum Pitch (IBR Profile) | 5° (1:11 slope) | Ensures high-capacity runoff for commercial spans |
| Fastener Spacing | Every crest/valley at eaves, alternate crests on intermediate purlins | Maximum uplift resistance against high winds |
| Purlin Spacing (Timber) | 900 mm to 1200 mm centers (varies by sheet thickness) | Supports dead loads without sagging |
Critical Installation Checklist
Thermal Expansion Spacing: Leave appropriate clearance holes for metal fasteners to allow metal expansion and contraction without tearing sheets.
Corrosion Protection: Use minimum Class 3 or Class 4 fasteners, especially in coastal or marine environments.
Flashing Overlaps: Ensure all vertical flashings overlap wall cladding or brickwork step-flashings by at least 150 mm.
Ventilation: Incorporate ridge or soffit vents to prevent condensation buildup within the attic space.