Understanding Thatched Roofs
By Charles Chalcraft, a Master Thatcher

The preparation of a Home Condition Report (HCR) on a thatched property requires the Home Inspector to have specialist knowledge about thatch and to be competent enough to identify the condition of the roof.  To do this a home inspector needs to be able to identify the type of thatch, to know how it is attached and how it works. There are about 80,000 thatched buildings in England and Wales and there are three main thatching types; Combed Wheat Reed, Long Straw and Water Reed all of which can be found on top of a wide selection of building types including, cob, stone rubble, stone, brick, timber frame and some new builds of concrete block or brick.                                                        

Regional styles of roof
There are a variety of different traditional regional shapes of roof and a number of different regional methods of thatching. In the West Country thatched roofs will be either Combed Wheat Reed or Water Reed and have a shallow pitch with a rounded shape.. Often multi coated, they can be up to 2m deep at the ridge.  The rest of the thatching counties have Water Reed, Combed Wheat Reed and Long Straw roofs, where the pitch tends to be steeper.  In East Anglia and the Midlands roof shape is more angular and Long Straw giving the appearance of being poured onto the roof frame.

How long will it last?
It is essential that NO home inspector or surveyor makes any indication as to how long the roof will last. There are many life spans of a thatched roof batted around and there is NO hard and fast gauge to use. The life of thatch depends upon many factors working together and largely depends upon the ability of the roof to dry quickly without over drying. Claims are wildly made that roofs will last for up to 60 years; in reality some roofs have, some roofs have also failed after 5 years.

Thatchers use the best quality reed that is available but straw and reed are natural products and there are good years and bad years. Other factors that will effect the life of a thatched roof include the position and location of the house, the pitch of the roof, trees, moss, birds, insects and animals, the skill of the thatcher, use of some fire retardants and moss killer sprays and poor roof design to name but a few.

Fire Precautions
Fire will always be a potential threat to all buildings whatever the roof is made of and thatched houses do not catch fire any more often than other houses. Most house fires start within the building and can be attributed to a number of causes including poor electric or gas appliances. There have been many attempts to fire proof thatch either by treating the reed before it is put on the roof, by spraying chemicals into the roof or by creating a fire proof barrier between the thatch and the roof structure. There are a variety of other fire barriers and there are special requirements for electrics in lofts. It is advisable for linked smoke alarms to be fitted in the loft of a thatched property and any netting over the surface of the thatch has to be fitted correctly so that it can be removed easily.

Older chimneys are often less than one metre in height from the thatch to the top of the chimney pot. Spark arrestors are now generally considered hazardous and unless they are removed and cleaned several times a year they can clog up with tar and restrict flue gasses. Ideally there should be a fire barrier placed between the thatch and the chimney.

The installation of woodburners and liners now comes under Building Regulations. In the past where open fireplaces cooled down over night, now woodburners can maintain a near constant and more intense heat that reaches further up the chimney - this dries out the lime mortar between the bricks which may be as much as 400 years old. When wet and unseasoned logs are burned the acidic tar produced can go through granite and lime mortar or corrode a stainless steel chimney liner. A close inspection of chimney stacks in the loft is necessary to detect any smoke or tar stains - if found then recommendations should be made to call in a chimney specialist.

The Condition of a Thatched Roof
New roofs and badly leaking ones should be relatively easy to judge. The part worn roofs will be more difficult to detect. Look for obvious signs of leaks - brown water stains running down the walls both inside the house and under the eaves and hollows, dips and gulleys in the coatwork. Thatched valleys and the area beneath chimneys are vulnerable spots but thatched roofs can be repaired and patched successfully. This is often done when a roof is being re-ridged.

This article offers you a very brief overview of thatch however if you are contemplating adding thatched roofs to your portfolio of expertise then you are recommended to undertake additional research and training.

Understanding Thatch - A course run by a Master Thatcher
The Understanding Thatch course will equip home inspectors to understand some of the complexities of how a thatched roof works, to appreciate the differences between the main thatching materials and between the different regional styles. With experience course delegates should then be able to undertake Home Condition Reports on most buildings with a thatched roof.

Suitable for estate agents, home inspectors, and surveyors, the course is 2.5 hours and qualifies for CPD.

The course will be led by Charles Chalcraft. Charles is a retired thatcher who worked in Mid Devon, and is an associate member of the Devon & Cornwall Master Thatchers Association, a member of the National Society of Master Thatchers and the Devon and Cornwall Home Inspectors Association. He has project managed three major house restorations and is a qualified Home Inspector.

If you are interested in attending the Understanding Thatch Course or a Hands On Thatching Weekend Course, please see further details at

email an expression of interest to or phone on 01837 840900.

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