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Thatching

publication date: Jun 26, 2007
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There is evidence of thatching in the UK dating back to the Bronze Age. Traditionally it was mainly found on ‘poorer’ dwellings, being a cheap readily available lightweight material. As such it was ideal for use on what were often cruck beamed, wattle and daub clad, relatively insubstantial humble homes, where the load bearing capacity of the walls was a major consideration. It was common to hold the straw in place with liberal daubs of wet clay and so must have appeared less than elegant, compared with our modern ideals.

The old name ‘thack’, still used in parts of Yorkshire and similar to the German word ‘Dach’, originally applied to any kind of roofing surface. As reed, straw and heather were used most frequently, it subsequently acquired today’s much more limited meaning. It was however utilised on many important structures and although records are limited, on Queen Victoria’s accession to the throne, there were 250 thatched ordained ecclesiastical structures in Norfolk alone. It is also recorded that in 1300, six acres of rushes were commissioned to cover the main hall and chambers of Sussex’s Pevensey Norman Castle.

However the threat of fire was ever present and the 12th Century Normans actually forbade the erection of any new thatched dwellings in London. It was common for the addition of a coat of lime wash, or lime plaster, to reduce combustibility.

Although thatch is not now thought to be the cause of the Great Fire in 1666, the only thatch building in London during the last 400 years to receive consent since is the Globe Theatre.

In Cambridge thatched buildings were restricted by order of Council in 1619.

Notwithstanding this, with the gradual rise of the merchant class and due to the lack of locally available alternatives, thatch gradually became common on their proud rural dwellings in rural Counties such as Suffolk, Cambridgeshire and Essex. Fire was still the major concern and long pole ‘firehooks’ adorned the side of many buildings. One can still be seen on a cottage in the High Street of the South Cambridgeshire village of Linton and I have read that there is another on an outside wall of a church in Welwyn Hertfordshire. These pole hooks were often also used to drag ponds and lakes for drowned bodies. Finally rapid decline came with the commercial production of cheap Welsh slate in about 1820, allied to transportation improvements, first with the canals and then the onset of steam railways.

Straws can include rye, oat, wheat reed, barley, scraw (Irish term for turf) and even heather. Locally, in northern Essex, by far the most common covering is long straw threshed wheat creating a ‘soft’ almost ‘poured on’ appearance, although combed wheat reed roofs (botanically no affinity to true reed), can be found in some places, as well as water reed itself. Locally, there were once great and extensive reed beds designated specifically for thatching use, both in the wetlands of Huntingdonshire and around the isolated granite Fenland intrusion, still known as the Ills of Ely. Conservationists today argue that the introduction of reed in traditional longstraw regions offends the ‘genius loci’ and they may have a valid point. Indeed during the 1960/70’s longstraw use declined rapidly in favour of reed (Phragmites Communis), but this was due in no small part to the very inferior quality being produced. Poor workmanship was also at fault, as traditional skills had largely been lost for the scale required, when renovation became increasingly popular during successive housing booms.

Long straw, hollow stem winter grown is best produced from old seeds. With the onset of modern machinery, in the late 1900’s, it was difficult to obtain quality longstraw for a time, as machine beaten and bruised long straw was deemed to be haulm (harmed). Some established firms even still grow their own. Old seed varieties include wonderfully named types such as Little Josh, red standard, aquilla, square headed master, maris huntsman and widgeon. The key to wheat straw quality is primarily in the growing and harvesting i.e. ground/growth preparation.

Straight, hard, high quality wetland water reeds from the Norfolk Broad lands can last 50 to 60 years.

The best reed is cut when all the flag (foliage) has withered, which is in mid winter. Imagine, in times gone by, how hardy the tough the Fen-man had to be to crop the reed, constantly braving winter’s raw elements, travelling amidst deep dark lonely dyke waterways in shallow, poled, punts. I am informed there is no high ground beyond Ely and the Eastern Ural Mountains to protect against those rough winds and base elements, so it must have been bitter, raw and unforgiving. It was therefore arduous to cut, is ever difficult to use and thus expensive. I have been told that the best English reed grows in brackish water, or where it comes into contact with a tide, such as a river estuary or a fen; the suggestion being that the salt pickles the reed a little. However, as it is not available all year round, cropping declined dramatically and today over 90% comes from Turkey and Eastern Europe; it is generally deemed inferior by those who know. Indeed it is argued that a high quality straw thatch roof can, with appropriate care, outlast European reed.

‘Life’ for longstraw, is dependent upon many factors but the main ones are shape, pitch, geography, topology, the quality of the material and naturally the Thatcher’s art. Frequently a new ‘spar’ covering of straw is added over the old; it is called a spar coat because this is the name of the split hazels, sharpened at both ends and then bent into a staple shape, forced down to hold the new layer in place. Reed is generally completely stripped away, prior to re-laying. Many consider sedge (Cladium Mariscus - a grass like plant with a stem devoid of joints) to be one of the best ridging materials, but due to exposure, even then generally requires replacement every 10 years or so. Thatch bundles are about 18 inches to 2 foot long and laid thick butt end facing. There are many wonderful terms associated to thatching but some you might have heard are a square, a usual basis of measurement being 10 foot by 10 foot, a yealm being a drawn, prepared, tight armful of long straw, whilst a nitch describes a 28lb reed bundle.

Many of the 100,000 UK thatched properties are either listed or located in Conservation areas, dictating the need for consent if alterations are required. Insurance premiums are generally higher, because when a fire does occur, its results are usually severe. A senior Cambridgeshire Brigade Officer once told me ‘show me a thatched property and I will show you where there has been a fire’. However many advisory thatching authorities consider the threat grossly overstated and quote statistics to prove the case. Further, nearly 90% of thatch fires are deemed due to the burning of fossilised fuels. As such, it is not surprising that the majority break out near chimneys. Similarly most fires are not on the surface, but underneath and can smoulder for a long time before erupting. An old fashioned fire prevention method was to plaster beneath the thatch and today barrier foil or something akin to thatch batts might be used, although some authorities argue that sheet or boarding on the underside of thatch causes sweating and so rots the material above.

Fire precaution

1. As a new owner of a thatched property take advice from your local Fire Authority, the Countryside agency, a reputable thatcher, or SPAB (Society for protection of ancient buildings)– I have also discovered both Leo Woods website at http:thatch.org and Keith Quantril/John Letts site at  http://www.building/ conservation. com/articles/longstraw, to be highly informative.

2. Fighting thatch fires is problematical and dangerous for any brigade – remember to tell them it is thatch, if you have need to dial 999.

3. Metal heat conducting materials should not pass through the thatch and fix aerials as far away as possible. Electrical wiring should be ducted through fire retardant conduit/ducting.

4. Plumbing joins should have compression fittings and keep a good length of hosepipe connected to a standpipe to hand in your garden.

5. Obviously avoid fireworks, bonfires etc.

6. Have an integrated main powered smoke/fire alarm system fitted.

7. Remember 85% of fires are chimney related. A stack should rise vertically at least 5 foot above the thatch. Have them regularly swept to avoid tar build up. Spark arrestors are good practice, but it is essential they are also regularly cleaned. Burn seasoned wood, avoid those high in resin and preferably use only smokeless coal. Although you should make certain chimney liners have been installed in accordance with manufacturer’s recommendations, remember that wood burning stoves generate intense heat which can sometimes crack liners, especially older ones – so again check and service regularly.

8. There are arguments against the effectiveness of chemical fire retardant additives to roof surfaces. Indeed some maintain such additives attack the covering, but on the strength of the evidence I am aware of, it still seems wise precaution to me. Surface spraying will only have a limited effect, especially as it wash off to an extent and not penetrate to the base. Soaking in retardant and then drying prior to use increases the cost, but is certainly effective.

Good husbandry and old wives tales.

1. Just because a roof looks a mess, that does not mean it needs re-thatching and the converse is also sometimes true.

2. Do not judge the quality of a thatch roof by its thickness.

3. A raised ridge may not be traditional, but it certainly IS more durable than a flush one.

4. Expect to find ‘split’ and bark pole common joist/rafter supports. A few cracked ones are by no means uncommon. This does not make it a poor quality’ roof in itself.

5. Moss growth is not uncommon or indeed damaging. However, it is unsightly and a thick layer prevents the covering from breathing and so leads to rot. Moss/lichen is most commonly found on north facing damp slopes. Removal is ideal but I strongly recommend this is work for your thatcher.

6. Thatch does not absorb high volumes of rainfall and guttering is not traditional and very uncommon. The water is actually transferred from stem to stem until it drops off the ‘cave’ at the bottom. However, people do not like water dripping on their head and this is usually why cottages have a storm porch above the front door.

7. Well laid quality thatch, especially with a wire covering, generally does have good wind resistance. Tests up to 100 mph in America are deemed to have proved it superior to many tile coverings.

8. Do not tread on thatch, place ladders against it or similar. Also cut back overhanging trees and severely restrict the growth of trailing plants such as ivy and clematis for obvious reasons.

9. Thatch does not require constant maintenance. However a good quality sedge ridge is likely to require replacement after about 10 years, while face (the surface of the main roof) fraying, can often be dealt with by trimming.

10.It is often said you do not require insulation between the ceiling rafters as thatch is its own insulator. I do not agree with this. Heat rises and the object is to warm rooms, not the roof void above. However humidity and condensation problems are also important considerations.

There is considerable myth and mystique surrounding thatched cottages and much is made of individual styling and the admirable embellishments you can find. Patterned ridges are considered to be ‘relatively new’ by purists, but together with latticed, parallel liggers and cross rods at the eaves, permit the craftsman much artistic licence. Common styles for the ridge can be plain, cross herringbone, straight cut block, scalloped, diamond, clubbed, dragon teeth and similar. Many of the best roof lines also boast individual styling by way of ornamental filials, otherwise colloquially known as ‘dollys’.

Some say these pheasants, leaping fish, running fox and peacocks were originally intended to scare birds or keep witches away. Others say they were intended to be something for a witch to play with and so divert their mischief elsewhere. I have even heard it said that a single pheasant was a mark of shame, because some craftsmen placed two ‘dollys’ on the roof, but the second was never added until after you paid the master thatcher! It is has to be a flight of imagination to suggest that cats and dogs found sanctuary amidst the warmth of tatty cottage roofs, because both longstraw and reed are sharp, uncomfortable and unforgiving. Even so, myth maintains that they did and that because they would subsequently fall from the slippery surface when it poured, gave rise to the popular every day saying ‘it’s raining cats and dogs’.

The fact remains that the soft, quiet yellow/brown handsome colouring of humble longstraw or sleek close textured reed thatch coverings, epitomise archetypal rural existence, sought by so many. Today there is a real desire to protect and enhance our rural heritage. People have an overwhelming desire to discover their roots and associate with a slower period of existence, when reality was not epitomised by catwalks, cyberspace and Twentieth Century technology.

Thatch speaks of warmth and welcome, stability and continuity; an impeccable rural association in an age when daily life proceeds at an ever increasing pace. This welcoming simplicity has somehow become the life they wish to rekindle. A radiance beyond deceiving, the seducing speed of strategic technology of business, to mirror a past and embrace a more gentle, basic time. With it, the glad fact remains that the Thatcher’s art is in the ascendancy once again.

BRIEN WALKER BSc (Est Man) FRICS, FNAEA. Building Surveyor in the Saffron Walden Essex practice of NOW WALKER Associates.