Roof Coverings and Underlays: Essential Concepts

Specific Roof Coverings and Regulations

IBR (Corrugated Iron Sheeting): Requires continuous support, specific overlaps, and secure anchoring to prevent lifting.
Concrete/Clay Roof Tiles: Must be uniform, interlock effectively, maintain color, have adequate overlap, and be secured with purlin straps for stability.
Thatch: Adheres to SANS 604h:1990 Part T; larger roof areas (over 20m²) necessitate professional consultation.

Definition & Purpose: A material installed beneath roof tiles to reduce suction, manage structural loads, prevent condensation, provide waterproofing, minimize wind noise, and enhance thermal performance.
Materials: Common types include asphalt-saturated felt, rubberised asphalt, non-bitumen asphalt, plastic sheeting, and sisalation.
Key Advantages: Acts as a secondary weather shield, offers waterproofing, serves as a condensation and dust barrier, protects insulation, prevents tile uplift, is vapor resistant, and is generally cost-effective.

Concrete Roof Tiles: Installation involves precise batten dimensions and spacing, calculated based on tile length and overhang to ensure proper support.
Thatched Roofs: Requires robust rafter pole installation, incorporation of fireproof materials, specific thatch thickness, and adherence to fire safety distances from adjacent structures.
Steel Roof Sheeting: Purlin spacing is critical for structural integrity and economic efficiency, influencing the required roof pitch.

Battens: Primarily used for fixing individual roof tiles, typically smaller in dimension and spaced closer together.
Purlins: Employed for securing larger roof coverings like corrugated iron sheeting, are generally larger and spaced further apart to support greater loads.