Insider Guide: Thatching
In our second Insider Guide, we’re turning our attention to thatching, a traditional roofing method which dates back over 2,500 years.
In itself, thatching has several advantages, not least its environmental credentials. It uses natural resources, and the harvesting of the materials it requires both encourages new growth and benefits wildlife. Thatching offers very good insulation, enabling the property to be warm in winter and cool in summer, and is also helpful for soundproofing. Importantly, also, a thatched roof gives a feeling of elegance and tradition to the appropriate dwelling, and can elevate the property’s value.
The downsides to thatching include the effect on insurance premiums – being combustible, it can inflate the cost of buildings insurance. At Anglian Home Surveyors we recommend that homeowners seek suitable insurance from companies that specialise in insuring thatched properties as their rates are likely to be lower than those offered by general insurance companies. The costs of maintenance and replacement can also be higher than for a conventional slate roof.
The main types of thatch used in the UK and the commonly quoted probable life expectancies for the principal thatching materials are as follows:
- Water reed, often known as Norfolk reed, which has a lifespan of around 50 to 80 years
- Combed wheat reed, which will last 30 to 40 years
- Long straw, which requires a wire mesh cover and will last between 15 and 25 years
- Sedge, which is usually used for roof ridges and has a useful life of 10 to 12 years
There are exceptions to these rules, with some cases of water reed roofs lasting only 15 years and long straw roofs lasting 50 years plus. The quality of the thatcher, their experience in using the material, the quality of the material, the pitch of the roof and geographical or meteorological factors such as wind can all be a major factor in the lifespan of the thatching. The key is to choose the right thatcher, who in turn will ensure the correct thatch materials are used to meet the demands of the location and design of the property within the constraints of listed building or conservation area requirements.
Thatching deteriorates over time, and there are several factors which can contribute to this process. Microbial action is one of the main causes, and this can be accelerated by moisture, so it is preferable to keep the roof as dry as possible, and the growth of moss and lichens can be controlled through chemical treatments. When nesting, birds are a factor as they frequently pull out complete strands of straw, but potentially more of an issue are rodents – including rats, mice and squirrels – as they can chew the straw into smaller lengths. Covering the thatch with a well-maintained wire mesh can help to prevent much of this damage. It is also not unheard of for bats to be present in roof space, and if this is the case, it is important to consult Natural England or the Bat Conservation Trust as the Wildlife and Countryside Act 1981 states that it is an offence to disturb them when in situ.
With the increased risk of fire that thatching presents, precautions such as ensuring any bonfires and barbecues are kept well away from the building can help to keep everyone safe. It is useful to fit a spark guard to the chimney stack, to have the chimney swept once a year and to test all electrical installations regularly in order to reduce the risk of short circuiting.
It is also possible to apply fire-retardant materials either beneath or on top of the thatch for further protection. Any use of fire retardents or fire protection barriers to roof slopes in the case of a total re-thatch needs to be carefully considered because although they may slow the spread of fire they may lead to reduced ventilation which in turn may cause more rapid degradation of the thatching material used on your roof. It is generally recognised that flue liners reduce the risk of fire to thatch and should be fitted where appropriate to those flues being used.
It is vital to maintain thatching effectively as it does degrade over time. The most noticeable deterioration is the appearance of hollows and soft patches, and the ridges will gradually wear away over the course of 12 years. A qualified thatcher can carry our routine maintenance, and an annual inspection will uncover any issues that need attention.
As a homeowner, it is down to you to maintain thatching and ensure the safety of anyone who enters the property. If you’re at all concerned about your thatched roof, or any other aspect of your property, why not call Raphael Stipic of Anglian Home Surveyors, a leading building surveyor in Cambridge, on 01223 661439?
It is important to obtain an independent survey of the condition of the thatch on the property you intend to purchase from an individual who does not have a vested interest in any potential financial outlay as a result of the survey.
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