The National Building Regulations and Building Standards Act specifies that roofs be designed and built such that the are safe and not easily damaged by wind or other natural force. Furthermore the law also specifies that roofs must be waterproof, but these are only basic requirements.
The law states that roofs be designed and constructed such that they are long lasting and not allow rainwater to seep into the interior of a structure nor shall a roof structure allow rainwater to accumulate on its surface.
The South African National Building Regulations Part L-Roofs covers:
- Roof coverings and waterproofing systems, and
- Drainage and waterproofing of flat roofs.
Roof Waterproofing Systems and Roof Coverings
The SANS legislation states that roofs be resistant to the incursion of rain to such that water in category 1 buildings (see below) not penetrate the roof and not run down the inside of walls onto the floor, or form puddles or damp patches on the building’s ceiling or the floor.
Roofs on buildings falling outside of category 1, should be designed and constructed such that any water penetration not be intense enough to allow water to run down the inside surface of the roof or drip onto the floor or ceiling. SANS legislation further states that roofing material and waterproofing systems must be able to be repaired if damaged.
Additionally, roof coverings must:
- Withstand temperature ranges from -10 degrees C to +80 degrees C, as well as rapid temperature changes of without failing
- Not deteriorate through the effect UV radiation
- Not be affected by sub surface condensation
- Withstand chemical attack from atmospheric salt or gas
- Not be affected by bacterial or fungal growth or of lichen growth
- Not be punctured or suffer penetration while the roof is in use
- Withstand movement
- Materials intended for roof coverings must have a minimum lifespan of 10 years or 20 years if the structure is difficult to replace