East Herts District Council

It is one of the oldest building methods still practiced today. In Hertfordshire, the thatching tradition has led to very attractive and distinctive roof forms that contribute greatly to the character of the county. In East Hertfordshire, most thatched roofs are in rural areas on a variety of buildings, such as pubs, barns, farmhouses, bus shelters, garden ornaments as well as houses. Each thatched roof is unique, consisting of a variety of roofing details.

It is desirable to re-thatch a roof in the appropriate original thatching material - normally long straw in East Hertfordshire.

Changes from one type of thatch to another need Listed Building Consent in the case of Listed Buildings. A change from thatch to tiles or slates would also require Listed Building Consent and is not generally recommended because of the alterations to structural roof timbers often required and the change in the building's character.

In terms of life expectancy, there are a number of factors to consider - including the degree of exposure of the roof and the quality of the material and the thatcher, but all thatches should last at least 15 years. Long straw if laid well will last for between 25 years - 35 years, combed wheat reed can last for between 30 - 40 years, and Norfolk Reed can last for up to 60 years.

New Works to Thatched Buildings

If you are contemplating an extension to a thatched building, there are several points to bear in mind.

The extension to be thatched. should be designed and constructed so that it is technically possible to thatch satisfactorily. Additional features planned may be quite unsuitable for thatch. In order therefore to avoid unnecessary expense and delay, it is always worthwhile discussing the outline proposals with a thatcher.
New windows should be of proportions and design fitting the building. Windows on the first floor should be eyebrow or eaves windows. Their design allows the proper draining of surface water. Dormer windows drain inefficiently, are costly to install and difficult to thatch. A particularly common problem occurs where new windows are planned in a position which makes thatching difficult. The thatcher requires space to work and turn his material. Thus windows, chimneys and vent pipes should be clear of the gables and valleys. It is also important to note that surface run-off will be greatest in the valley joining the existing thatch to a new extension.
New rafters should be at least 2 inches deep in order to hold thatch hooks.
A new thatched roof should have a minimum pitch of 45 degrees.
Providing gutters can be a problem, since they look unsightly and cannot be secured very easily. It is rare to find gutters on a thatched roof, although where found, they are usually of timber and of much wider section than modern gutters. Timber gutters are less likely to clog with fragments of thatch and can be lead lined to prevent leakage.

In new buildings, the chimney should conform to the Building Regulations. Easy access is advised in order to regularly inspect the condition of the stack. A new stack should ideally be placed at the ridge to avoid awkward detailing. Lead flashings can be secured to the thatch at the base of the chimney, although a lime-based mortar may also be used.
Always ensure that the building is properly insured during a building contract and that strict fire precaution measures are taken at all times by all workmen on the site.

The Ridge

Patterned ridges or a block ridge, with hazel liggers are not traditional. They first appeared in the mid 18th Century. The traditional finish for a long straw thatch is the flush ridge, a simple and unfussy finish. The patterned ridge which many thatchers decorate as their trademark arose from the use of reed in thatching, which could not be bent over the ridge. The ridge lifespan is shorter than the rest of the roof, since this bears the impact of the rain, snow and wind. A ridge may require re-thatching after 10 - 15 years, although this is only a guideline, since each roof is unique. Again, a thatcher will advise you if the ridge should need renewing. If you are contemplating the renewal of your ridge, it is preferable to encourage the historic tradition of the simple flush ridge with a long straw thatch.

Thatching Materials

There are three main thatching materials - long straw, Norfolk or water reed and combed wheat reed. Long straw is the traditional thatching material in East Hertfordshire being the most readily available. Though Norfolk reed thatching does exist in this area, it is less common and not a local material. Combed wheat reed is alien to East Hertfordshire.

Long straw thatch - the wheat used for long straw thatching is grown specially. The wheat is subjected to strict control of fertilizers and other modern farming methods, so the quality for thatching is sustained. Farmers who grow wheat for thatching tend to specialise in it. The wheat used for straw thatching is harvested when it is slightly green, of lengths of 2.5-3 feet. Long straw is composed of loose uncombed material which is dampened and shaken into a bed. It is then pulled out and formed into Yealms (bundles) ready for laying.

Long straw thatch has a distinctive appearance, with both ears and butts visible on the surface with a thickness of at least 15 inches. It is also recognisable by the hazel spars and liggers (see glossary) which hold the straw in place. Long straw is always covered with wire netting to protect the thatch from bird and vermin damage. If a tree overhangs the roof of long straw, netting is not used since this catches leaves and causes rot and fungus

Water reed is less common to East Hertfordshire, being a native of East Anglia, and was used on a limited number of C19 estate cottages and early C20 houses. Some reed is now imported from the continent. The reed needs to be about 4 feet long, and when laid looks harder than straw.

Liggers and spars are not used at the verges of gables and eaves.

Combed wheat reed - this material was originally produced by combing the ears and leaves of wheat from the stalk, to leave a straight reed. It also must be about 2.5-3 feet in length and the finished thatch about 12 inches thick. All the sharp stalk ends are exposed, so that the rain drips off the end, rather than running down the roof, as with long straw.

Choosing a Thatcher

Skilled thatchers generally undergo a 4 year training period, and are usually members of the Master Thatchers' Association. It is best to obtain estimates from more than one thatcher in particular, ask the estimating thatchers to provide names and addresses of properties where they have worked, so that you can inspect the thatch and establish their expertise and talk to the owners!

Approach the local Master Thatchers' Association who will be able to offer a specification for the work. Also, if a thatcher is at work in your area, then first hand experience in his techniques and ability are there for you to see. Finally, select a thatcher who knows the local traditions, the climate, and local suppliers of long straw.

Thatching Repairs

It is often unnecessary to thatch a complete roof. Instead, patching or replacement of the straw or reed can be undertaken to remove the decayed material. This enables the lifetime of a whole roof to be extended.

There are several indications to show when repairs are necessary. Where the netting is loose and the long straw has begun to shift, it may be possible to patch the appropriate area. In particular, repairs around the chimney and to the ridge must be carried out every ten years or so - this gives an opportunity to check the condition of the chimney as well. However, there will come a time eventually when the whole roof will require replacing.

Signs to be aware of are obvious vertical lines in the thatch, which show that the courses of long straw or reed are rotten and exposed hazel ties and spars that have moved, or visible holes.

The holes show that birds and animals are attacking the roof.

A further major sign of the failing of the thatch is dampness. A damp thatch will often have patches of moss and fungus growing on it. The dampness weakens both the thatch and the roof structure, and the roof will require rethatching imminently.

Assessing the remaining life of a thatch is not easy. The rate of deterioration varies greatly, according to the location, thatching material, the thickness of the coat and the skill of the thatcher.

If it is possible to obtain details from the previous owners about the history of the roof, it is best to do so. It is not advisable to disturb the thatch and maintenance by way of climbing onto the roof should be kept to a minimum. If you have any doubts about the length of life span left in the roof, it is always best to consult the original thatcher. If he is not available seek another member of the Master

Thatchers' Association

A long straw thatched roof is not normally stripped to the rafters. The lowest layers of straw tend to be left in place, often dating from the time of the first coat. These layers provide an invaluable historical record of the traditional thatching techniques, such as tarred cord ties and split hazel sways. A water reed roof is completely stripped to the bare rafters and new reed applied.

Costs of Repairs and Re-Thatching

There is no clear cut cost of a new thatched roof. The price is dependent on many factors including the following:

The size of the roof and the number of valleys, junctions or other complex features such as dormers and eyebrow windows.
The availability of the thatching material and its type, and
The availability of a thatcher.

Other 'hidden' costs, which are only revealed once the thatch is removed such as repairs to the structural timbers which support the roof

Causes of Fire and Precautionary Measures

Fire is an extremely worrying aspect for the owners of thatched roofs. Historically thatch would often catch fire from spark' from the open fire through the smoke vent in the roof.

The introduction of brick chimneys reduced the danger, but nevertheless, a thatched roof is always at risk from fire. It is essential therefore to be prepared - adequate water supplies and speed are of the essence. An adequately sized loft access is essential for Firemen's access.

The commonest causes of fire in thatch are:

1. Electrical faults,

2. Lightning affecting the television aerial on the roof,

3. Stray sparks from the chimney, discarded cigarettes and garden bonfires.

Fire Precautions

1. Establish a water supply with adequate pressure to extinguish the fire. A swimming pool, pond, river, or spring are possible sources of water.

2. Speak to a fire officer at the Divisional Fire Office who will offer advice about fire precautions. Speak to the Fire Brigade if you believe you face particular problems.- this may be so if the property is isolated.

3. Fit the television aerial or satellite dish to a free standing pole, some 20 feet distance from the thatch. Alternatively, the aerial could be attached to a gable end. Aerials are at risk of conducting lightning and starting a fire.

4. Check electrical wiring routinely. This is a major cause of thatch fires.

5. Regularly look in the loft area for straw debris, and remove. Never store combustible items in the loft space, these can start the fire in the first place.

6. Enclose electric lights in the loft space in glass. Avoid leaving lights on in the loft unnecessarily.

7. Sweep chimneys twice a year, and do not use fuels which emit smoke or cause sparks or unseasoned logs.

8. Maintain a draught free roof space. A draught will fuel a fire.

Precautions which an expert should undertake:

FOR YOU

1. Ensure that new rafters are coated in a fire retardant.

2. Ask your thatcher to check the pointing and mortar joints of the chimney stack. Those joints which are hidden from view below the thatch may well require repointing.

Steps to take in the event of a fire:

1. Call the Fire Brigade immediately. Remember to inform them that the property is thatched.

2. DO NOT ATTEMPT TO REMOVE THE BURNING THATCH

- this will only fuel the fire.

3. Evacuate all occupants, closing all doors, windows and hatches on the building.

4. If it is safe to do so, use a garden hose with adequate pressure to help extinguish the fire, before the Fire Brigade arrive.

Glossary Of Thatching Terms

Leadwork-this provides an invaluable drainage system to the roof, particularly at valleys and also around the base of the chimney on the thatch.

Liggers - hazel sways which are about 3 feet long, used to secure Icing straw roofs at the eaves, barges and ridge. Liggers are used in reed roofs at the ridge only.

Netting - this is used with long straw thatch - it protects the straw from being pecked away by birds. It is not there merely to hold the thatch on. Netting does have disadvantages. It can trap leaves and other debris, and can prevent the smooth flow of surface water. This in turn may cause the growth of moss and fungus. It is also a drawback if there is a fire, for there is delay whilst the netting is removed. The netting is laid vertically from ridge to eaves and does not overlap, but is secured with special metal hooks at 9 inch intervals.

Sways - split hazel rods about 9 feet in length used to secure the courses of thatch as they are laid. Metal hooks hammered into the rafters secure the sways.

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Thatch

Introduction