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Lightning protection for thatched roofs

It’s a reality that thatched roofs are extremely popular in South Africa, both within many rural communities and a number of upmarket developments. Constructed of soft material, such as straw, reed, grass or coconut leaves, a thatched roof is more susceptible to catching alight as a result of a lightning strike than any other roof type, according to the South African National Standard (SANS).

When a thatch roof is constructed, wire mesh is used to reinforce and secure the bundles of thatch. Should lightning strike, then current flows through the wire mesh and the thermal effect (generated heat) may occur, and set the roof alight.

Dehn Africa can assist homeowners in avoiding lightning related disasters through the provision of lightning protection system (LPS) components for use specifically on thatched roofs. The company recently introduced new methods of protecting thatched roofed structures in South Africa, and it is no longer necessary to have a 30 metre long mast installed.

The latest preferred external protection system for installation on thatched buildings is the high-voltage-resistant insulated (HVI) lightning protection system that is compact, neat and approved by leading insurance companies and SANS.

For protection measures to be successful, air-termination conductors on thatched roofs must be installed as elevated traverses, for example: on isolating supports, with certain distances also to be kept for the eaves. LPSes should be designed to provide sufficient low impedance so that the lightning energy can follow in the required route. This requires an integrated design and effective use of material with enough low impedance. For protection measures to be successful, air-termination conductors on thatched roofs must be installed as elevated traverses, for example: on isolating supports, with certain distances also to be kept for the eaves.

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