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Fire retardants for thatched roofs

Statistically homes with a thatched roof are no more likely to catch fire than those with a conventional tile or slate roof and nationally represents a small percentage of house fires.

However, the results can be devastating and losses can be extremely high as many thatched properties are listed which invariably leads to higher repair costs. Thatch roofs are designed to repel water making them more difficult to extinguish, which can result in increased damage to the entire property.

There are many measures to reduce the risk of fire one of which is treating the roof with a fire retardant spray.

Which retardant?

A water-based solution of fire retardant and intumescent chemicals in a polymer emulsion binder specifically formulated for the protection of thatch roofing. It should be environmentally friendly with no detrimental effect to plants or animals and of course have no adverse reaction to the thatch.

Fire retardants for thatched roofs should not contain any borates or borate-based additives.

Application

Fire retardant sprays should be applied by trained personnel using high-pressure specialist equipment to treat not only the thatch surface but also the thatch stems to ensure a degree of protection for a number of years.

All too often fire retardants are applied to just the outer surface of the roof (often with a garden-type sprayer) only for them to ‘run-off’ due to the liquid repelling nature of the thatch.

The application should be carried out at a certain pressure using a specific tip spraying upwards into the thatch coat work at the angle of the roof ensuring penetration of between 50mm and 75mm.  This will ensure the fire retardant is applied to both the surface and thatch stems.  On an older roof or specific types of thatch, the pressure can be reduced.

When to apply?

There should be no rain for a minimum of four hours prior to applying a fire retardant, ideally the roof needs to have been exposed to direct sunlight for two hours prior to the application.

Due to the high levels of moisture in the air during the winter months the application is normally carried out between the end of March and at the very latest, depending on the long-range forecast, the end of October. After this time, the damp conditions can slow the curing process and leave the roof more vulnerable to the risk of a rain shower during this time.

Why treat a roof?

The latest report from fire investigators, Burgoynes revealed that out of the 103 thatch fires they investigated between December 2008 and July 2013, the most common cause identified was an ejected ember (64), with the next being a chimney fire (11).

http://www.burgoynes.com/fires-thatched-buildings

Which product?

Thatchsayf is a water-based solution containing fire retardant and intumescent chemicals for the protection of thatched roofing.

When applied correctly, Thatchsayf penetrates the stems of the thatch by up to 75mm and will also form a thin protective film on the surface of the thatch stems.

On exposure to heat, Thatchsayf will foam (intumesce) and form a carbonised char, binding the thatch stems together, cutting off the supply of oxygen to the fire and delaying the spread of flame and lowering the radiated heat output.

Thatchsayf is environmentally friendly, can help prevent bacterial and fungal growth and has no detrimental effect on the thatch.

What are the benefits?

  • Reduced insurance premiums
  • Fire penetration delayed for over 30 minutes
  • Can be applied to new or existing thatched roofs
  • Prevents bacterial and fungal growth inc. moss
  • Application is fully certified

A roof treated with Thatchsayf will offer protection from a number of fire risks, including sparks, ejected embers, bonfires, Chinese Lanterns, fireworks and barbecues.

Thatchsayf is tested to BS476: part 3: 2004 and achieved the designation of EXT.S.BA.

Once a roof is treated, the homeowner will be issued with a Certificate of Completion, which can then be issued to Architects, Building Control Officers, Insurance Companies etc. as proof that the thatch has been correctly treated with Thatchsayf. Certification is valid for 5 years before re-application is required.

Many specialist thatch insurance recognise the application of Thatchsayf and will offer a reduction in premiums to those taking a pro-active approach in reducing the risk of fire.

The application of Thatchsayf is undertaken by trained and approved contractors using a high pressure spraying system. This ensures that the correct pressure and coverage is applied to the thatch.

A typical roof should take no more than a day to treat and will dry within 3-4 hours.

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