The information in the article below is provided by Jem Raison, Master Thatcher.
Thatch is a general historic term for any type of roof covering involving vegetation. Although it now applies chiefly to straw and naturally growing water reeds (Norfolk reed), cottage roofs have been covered with heather (Scotland), grass (West of Ireland) and Bracken (Yorkshire).
It would have been the first ‘man made’ roof covering after our ancestors left their caves. From the time of the Roman occupation right through to the Victorian age the cheapest way to roof just about any building, whether temporary or more permanent, was with a type of thatch. Only the wealthier in society could afford clay tiles as a more effective and secure roof (The Romans probably introducing the technology for this). The heathers, grasses and bracken mentioned above would have been readily available and in later centuries the straw from cultivated crops would have provided a cheap by-product of the annual grain harvest. Only in areas where a convenient and superior material was available would thatch quickly decline during the late 18th and 19th centuries. These areas were Wales, and the north of England with their slate quarries, the Cotswolds with stone which split easily to make stonesfield slates and London and the south-east where bricks and tiles were being manufactured in huge quantities to develop the major city conurbations.
Thatch survived almost by default in the more rural areas, predominantly the south-west but also East Anglia, Hampshire & Wiltshire together with the south midlands. During the 1950’s and 60’s thousands of thatches were stripped off and replaced with tiles and only during the later 70’s was this destruction halted. Now, 90% of all thatched houses are listed so that they must continue to be thatched. The trend has even been reversed in Dorset where many new houses are now being thatched to increase the stock.
The main advantage of thatch is that most of us like to look at it! The aesthetic appeal of a thatched country cottage is almost universal and although it forms a good layer of insulation (warm in winter yet cool in summer) that’s about it! On the down side it’s not cheap to live underneath with maintenance and insurance costs being inevitably greater than those of a tiled or slated roof. These days, however, buying a thatched property involves a conscious decision to do just that and with careful planning and paying for reliable professional advice the risks can be minimised.
Fireproofing an old thatch is not practicable, most straw based thatches consist of an accumulation of old layers with the most recent coat pegged on top. Some of the old thatch underneath can be up to a hundred years old and there is no guaranteed method of impregnating the whole mass of thatch on the roof. New build thatch can have fireproof barriers fitted to the roof timbers before the thatch is applied (see ‘The Dorset Model’ under building regulations for thatch).
With regard to care there are no hard and fast rules but the old saying ‘a stitch in time saves nine’ could have been coined for thatch. The best advice is to find a reputable local thatcher and request an inspection every three to five years. This will allow a trained eye to identify any potential problems before they begin.
The cost of thatching will vary slightly around the country, but it will vary a lot depending upon the complexity of the roof, access to the building, condition of the existing thatch and so on. A ‘ball park’ figure to include all thatching types, scaffold and Vat would be £180-£200 per square metre. But in any individual case it is most advisable for clients to obtain a written estimate before making an offer to buy a property.
The first port of call is the local thatching fraternity. There are courses available but they only augment an existing apprenticeship so the hopeful trainees will have to find a thatcher willing to take them on before they can be enrolled on such a course.