Blog detail

Fire in thatched properties – And how to avoid it
Fire in thatched properties – And how to avoid it
By Dom In Thatch News Posted 2nd July 2015 0 Comments

In this post our resident thatched home insurance guru Richard Playle takes a look at fire in thatched properties, its causes and the best ways to avoid it.

Thatch fires are rare

Fire is not a regular occurrence in thatched properties. If it were, the built heritage of this island would be poorer by some 40,000 properties. It is, however, an issue that owners and potential owners of such homes disregard at their peril.


Statistically, Home Office figures seem to indicate a much higher ratio of fires in conventional houses compared to those with thatched roofs. However, because these include high-density urban housing and multi-tenanted properties they are not representative of the true picture.

Of the estimated 50,000 thatched buildings in the UK, Fire Service statistics indicate that between 60 and 70 will suffer serious fire damage in any year. Of these fires, more than 85{fcb871d8a172bdb5e6d9fafd8c8457933956cb61c42680abaa1188974828c2e1} will be directly linked to the burning of wood or fossil fuels.

It should always be remembered that thatch is an organic material, subject to different behavioural patterns depending on its surroundings and treatment. It has a finite life span, measured in tens rather than hundreds of years, and above all it is combustible. Good housekeeping and a constant awareness of potential danger are essential if the unthinkable is to be avoided.

Thatched home chimney maintenance

Chimneys in old houses are frequently single skin brickwork with lime-mortar based joints and pointing. Years of external weathering and internal attack by the corrosive sulphates in flue gases can lead to gaps in the cement fillets, allowing inflammable tars to leach into the roofing material.

A visual inspection of the exposed stack will highlight any obvious problem areas but hidden patches within the roof can only be dealt with when a re-ridge or re-thatch is undertaken. It’s essential that when this work is in progress, the opportunity be taken to undergo any repairs and repointing necessary before the thatch is replaced. Reputable thatchers will do this as a matter of course but it’s in the householder’s own interest to satisfy themselves this has been done.

Another essential maintenance procedure is getting chimneys swept. The following is taken from a publication by Dorset Fire and Rescue Service:

“It is vital that flues are regularly swept. Owners should assure themselves that their sweep is experienced in the type of fire, flue and fuel combination in use. Intervals between sweeping will depend on the fuel burnt and the frequency of burning, but it must be a minimum of twice a year; once toward the end of a burning season and again prior to the start of the next to ensure a flueway clear of any obstructions, such as nests, as well as flue deposits. If wood is burnt, the frequency of sweeping should be increased.”

Safe electrical installation for thatched properties

Electrical faults are the second largest cause of fire damage in thatched properties.

Most insurers now insist that an inspection is carried out on a regular basis (varying between 5 and 10 years) by a NICEIC approved contractor, but householders are recommended to do their own, purely visual, check on at least an annual basis. This needs to be no more than ensuring there are no broken fittings, bare wires, overheating sockets, or fuses that frequently blow or trip out. If such problems are discovered, always seek professional advice.

Due to the higher risk of vermin damage, exposed wiring should be avoided in lofts and in particular kept away from roof rafters in close proximity to the underside of the thatch. All light fittings in lofts should be of the enclosed, bulkhead style.

In the recent past, most installations were fitted with an “earth trip” situated between the electrical meter and the consumer unit. This cut off the supply in the event of a disruption in the circuitry. In the majority of electrical installations this has now been largely superseded by the even more effective RCD (residual current device). This is a far more sensitive safety device and its employment is now strongly recommended to cover all circuits.

The safety of domestic installations is covered by BS7671 (amended) and contractors carrying out inspections will in most circumstances apply a coding to defects found, based on their level of importance from a health and safety or material damage aspect. A copy of the definitions for each code can be found below.

It has to be said that the amendments to BS7671 are a constantly moving feast and are currently (March 2010) on the 17th edition. Care should be taken when agreeing to additional work by a contractor that this is of significance and not merely to allow the circuitry to comply fully with the latest edition.

About Spark Arrestors for thatched homes

In recent years spark arrestors have received a mixed press from both the fire service and insurers of thatched properties, with no definitive decision by either on whether they are a good or bad investment.

If your chimney is around the 1.8m recommended height above the surrounding thatch and is free of all impedimenta such as slabs, ridge tiles or “T” shaped terminals, the fitting of such a device should not be necessary.

If, as is the case with longstraw, coats of thatch have built up over the years and the height has been drastically reduced, they are worth considering, but the best course of action is to have the height of the chimney raised.

If contemplating a spark arrestor, look for the type that fits on top of the chimney pot. The over-riding problem with spark arrestors has always been the ability of the owner and sweep to keep the mesh clean and unclogged; if this is not regularly done they become a danger to both the property and the health of the owner.

Thatched homes and burning wood

Burning only seasoned timber is not only cost effective (it produces almost 50{fcb871d8a172bdb5e6d9fafd8c8457933956cb61c42680abaa1188974828c2e1} more heat energy than freshly felled timber), it is also safer, producing far less corrosive tar and hydrocarbons and less sparks.

To ensure a supply of seasoned timber, a proper regime needs to be established. Ideally, timber from trees felled in the preceding winter or early spring needs to be stacked on a sunny site until the following autumn and then stored under cover to prevent re-absorption of water. It is best to bring logs into the house a few weeks before burning to complete the drying cycle. The optimum thickness of logs for burning is 10cm as wood is a poor conductor of heat.

Although it is well known that wood from broadleaf trees (beech, oak, ash, etc.) has the best burning efficiency and calorific value, it is sometimes more difficult to obtain. Pine and Douglas Fir (provided they are properly dried in the prescribed way) will still give around 80{fcb871d8a172bdb5e6d9fafd8c8457933956cb61c42680abaa1188974828c2e1} of the effective heat energy obtainable from the broadleaf trees, but be aware that pine (along with elder) is the worst wood for producing sparks.

On the subject of sparks, if you are using an open fire, logs will spark less on a bed of ashes on the hearth than if burnt in a log basket.

4 more key safety measures for owners of thatched houses

1. Smoke detectors: One of the most cost effective of fire safety devices. In thatched houses it is recommended that, where an attic is accessible, a smoke detector is installed as near to the apex as feasible and linked to a second detector on the landing or hallway.

2. Tradesmen: One of the biggest thatch fires in Sussex was caused by a plumber igniting the generations of cobwebs in the roof void of the property whilst working with a blowtorch. Never automatically assume that any person invited on to your property in whatever capacity will act with common sense.

3. Bonfires: Another common sense issue, but tantalising if you live in the country! Choose a windless day (preferably raining!), do not use accelerants to start the fire, keep it small and at least 50 meters away from the nearest thatch. Keep a connected hose nearby.

4. Overhead power lines: If the line to your property is a single, black PVC covered cable, all is well as long as it is not allowed to become entangled in any nearby trees. If it consists of two or more separate wires you should talk to your local electricity company; they may upgrade it free of charge.

Fighting thatch fires

The success or failure of the Fire Service to control fire in a thatched roof is largely a question of timing. If they are able to attend at an early stage there is frequently the opportunity of rescuing at least some of the property. However, because a fire can be spreading within a roof for a considerable time before it is apparent on the surface, this is sadly a rare occurrence.

Pouring water on a burning thatched roof has little effect other than containing the fire, as penetration is unlikely to be more than 5 – 6cms. To put the fire out, the thatch is dragged from the rafters and hosed down. If safety and circumstances allow, firefighters will endeavour to cut a firebreak through the thatch ahead of the fire. Due to the volume of smoke created and the unpredictability of fire spread, this operation is fraught with danger as breaking through the tightly packed thatch allows in oxygen and may simply increase the burning rate.

New firefighting techniques are being tested by a number of brigades. West Sussex are working on a trident-like attachment to the fire hose, which is stabbed into the thatch, enabling deeper water penetration.

Insure a thatched house with confidence

Although thatched homes represent a very small proportion of Britain’s overall housing stock, the cost of attending a thatched fire is substantial. The average house fire costs £6,000 in brigade manpower and materials; thatch fires cost an average of £23,000. It’s obvious good quality thatched home insurance is vital. As experts in the field, we’re the perfect fit.