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FAQ for DEHNsure

If you have a question about a particular topic that you do not see in the list, please contact us and a member of our team will help you.

Contact us directly from the Contact tab or ask one of our approved installers from the Installers tab to initiate the process. We will help you by either inspecting the roof first and then making a proposal or by using submitted information to design and prepare a proposal for your thatched roof.

Every roof has a different shape, size and height, and a special system needs to first be designed before the cost can be worked out. Installers also have different costs for labour and travelling if the site is remote.

A basic DEHNsure lightning protection system done correctly is in most cases less expensive than traditional old mast lightning protection systems which have been done correctly according to SANS standards.

If electrical and electronic systems inside the building are also to be covered by DEHNsure (optional), more surge protection devices will add to the costs.

Contact us or our approved installers to get in indication of the pricing.

Depending on how remote the area is, how large the roof is, and how accessible the points where the system must be installed are, the whole process can typically take 2-3 weeks.

The installation of the system by approved installers typically only takes 1-2 days for a standard building.

The DEHNsure concept requires a fully installed lightning protection system according to SANS 62305 with DEHN parts.

The roof will be accessed at the ridges from the inside and outside, where a hole needs to be made and re-sealed. The supporting tube/HVI mast is mounted with bolts to the wood or metal beams that hold the thatch.

The HVI conductor is mounted to the beams that go down to the walls, and then routed further to the ground. The ground is broken where earth rods are installed 3 metres into the ground from the surface.

Equipotential Bonding Cables (“Earth Cables”) are run underground or along the walls to the Electrical Main Distribution Board (DB) to connect all the earthing of the building together.

A Lightning Capable Surge Protection Device is installed by an electrician into the Main DB and connected to the same system to ensure safe and predictable handling of lightning currents.

If electronic systems are also to be covered by DEHNsure (optional), all the systems declared must have additional DEHN surge protection installed at the equipment, such as inside plug points and on communication cables (DSTV, WiFi, etc.)

Lightning protection has complex standards that should be followed to make sure between 79% and 98% of lightning strikes are protected against. Thatched roofs should generally be covered against 86% of lightning strikes.

Basically, this percentage of lightning strikes must be intercepted by parts that are designed to handle the strong forces of a lightning bolt, safely take the lightning bolt’s current to the ground and dissipate the energy into the soil. To prevent fire, nothing must come loose or spark over to other parts of the building, which tested, robust parts can ensure.

Electrical and electronic parts are also able to carry lightning and surge currents unintentionally. To make sure nothing breaks in this case, surge protection devices are designed to handle the currents and reconnect them to the earthing system. They make sure the devices and wires don’t reach voltages that are too high to handle.

The international standards that South Africa has adopted give a calculation that can be done to see whether you need lightning protection or not. It depends on many factors, but is largely influenced by the size of the building or system, and what type of lightning activity is common in the area.

A thatched roof building is always required to have lightning protection according to South African National Standards due to its highly flammable nature.

Lightning strikes to thatched roofs can obviously cause the roof to catch fire. Once a thatched roof goes up in flames, it frequently burns very quickly and can then spread to the building itself, creating a total insurance loss – never mind the potential loss of life to both humans and animals.

A lightning strike can also cause huge magnetic fields to move over electrical wires which creates surges that can damage your electronic equipment and appliances. Therefore, a complete lightning protection system (LPS) needs to provide external protection from the possibility of an actual direct lightning strike, which could cause the roof to burn, as well as internal protection against the possibility of a surges as a result of lightning, which could damage the electronics.

A surge protector is designed to limit unwanted impulse voltage caused by lightning or other surge sources. While surge protection devices don’t eliminate the risk of damage, they substantially limit the damage caused by lightning and power surges.

This allows electronic devices to continue operating without any intervention.

When a lightning protection system is installed, the lightning currents need to be controlled everywhere they might enter. For this reason, a lightning capable surge protector is used to prevent catastrophic damages to the electrical system.

A freestanding lightning mast, which varies in length from around 10 to 30 metres, works by intercepting lightning strikes when they occur in the area. By protruding out further than any other parts that need to be protected, lightning attaches to the tip of the masts and gets conducted to the ground. The mast needs to be strong enough, be electrically continuous as well as earthed and bonded sufficiently for everything to behave as expected.

The mast is positioned to make sure possible lightning strikes to the area will attach themselves to the mast instead of the building being protected. Smaller lightning strikes can also come into the area somewhat sideways, and sometimes more than one mast is required to prevent lightning from hitting the sides of the building being protected.

If you install a free-standing lightning conductor mast, you also need surge protection, as the mast will not be enough on its own to prevent damage to the equipment in the building.

A freestanding external lightning conductor mast needs to be properly maintained, at least annually, to ensure it stays in fully working condition, especially with lower quality parts that are prone to rust and wind related damage.

DEHN’s high-voltage-resistant insulated (HVI) technology is recommended for many reasons.

The conductors can easily maintain separation distance and prevent lightning from sparking anywhere to the building and its systems - Installation takes place directly next to conductive structural parts or electric lines or pipes without danger.

The HVI technology is extensively tested in our DEHN Test Centre – with the one of the biggest lightning current generators in the world – a fully accredited and competent laboratory in Germany.

Appearance and design are becoming increasingly important for modern buildings, and DEHN’s HVI conductors and more aesthetically pleasing and are shorter and more compact than a traditional 30 metre mast.

The HVI systems are easy to mount and have many available combinations for different scenarios.

The HVI components are also flexible when retrofitting to existing buildings. Existing thatch roofs are the most common installations.

Maintenance is simpler than masts. With high-quality, robust parts, damage from rust is prevented – and are tested to still work even when they’re corroded. The modularity makes parts that need to be changed out at a later stage for any reason, easy and cost effective compared to masts.

HVI systems are designed to withstand high wind loads. They are rated to never bend permanently or break even in the roughest storms.

They can be installed behind walls and facades, while HVI conductors with grey sheathing can be painted the same colour as the building.

For the client (homeowner and architect) this means optimal adjustment to the architecture of the building and new design possibilities.

HVI lightning protection systems have been tested and proven in the field since 2003. This lightning protection system passes strict tests with simulated lightning in our labs, which is backed up with successful real-world applications for more than 16 years. DEHN is so confident in a correctly installed system, that it is willing to cover failures or damages, which are highly unlikely, up to the amounts declared by the client at the installation phase. DEHNsure is a testament to DEHN’s confidence in our system.

Thatched roofs are highly flammable and when they catch alight, they burn quickly, even if firefighters are able to get to the scene timeously. This means that from an insurance company’s perspective, there is a greater chance of having a total loss from a thatched roof fire than there is from a fire made of non-thatch material.

A thatched roof is regarded as a non-standard construction by insurers, as compared to tile, slate, concrete, asbestos, metal or zinc roofs, which are deemed to be standard.

Before an insurance company will provide cover on thatched roofs, certain requirements must be carried out. These include having the roof professionally installed and making sure that the owner carries out regular maintenance.

In addition, the owner must take steps to reduce fire risk, including protecting the thatched roof from possible direct lightning strikes. Another risk from lightning comes in the form of resultant power surges, which can damage electrical equipment and appliances.

The insurance company will consider the protective measures that have been implemented to safeguard the thatched roof when determining the insurance cover and premium.

All thatched roofs need to be installed and maintained by professionals in order for insurance to be offered. You will not be covered if your thatched roof is of defective design, specification, construction, workmanship or material.

The top layer of thatch degrades over time and needs to be brushed every five to eight years. When the roof reaches a minimum thickness, it is time to re-thatch.

You will not be covered if your building is not maintained properly or has been damaged over a period of time by mildew, damp, or wet- or dry-rot.

No. Fire retardants slow the heat build-up in the event of a lightning strike on a thatched roof, or sparks from a chimney, but they do not actually stop a fire. They can assist in preventing a flame in the thatched roof from catching, thereby drastically reducing the chances of the fire growing, as well as how fast the flames grow.

Different types of extinguishers are designed to fight different types of fires. Carbon dioxide or “B” class extinguishers are best in cooking areas. Water extinguishers or “A” class are best to use directly on the thatch and should be kept on every floor or loft if the building is higher than one storey. Remember to service all your extinguishers annually.

Yes. Thatched roofs covered with thin steel tiles have many advantages for the longevity of the roof amongst other benefits.

Roofs with Harvey tiles also require lightning protection, because they are too thin to safely handle lightning currents. DEHNsure and DEHN’s HVI systems also work with these roofs.