Thatch roofing is one of the may ways to achieve sustainable and low cost housing specially in rural areas.

1. THATCH ROOFING
ACROPOLIS INSTITUTE OF
TECHNOLOGY AND RESEARCH,
INDORE
DEPARTMENT OF CIVIL
ENGINEERING
ANKIT SHAH,
ASST. PROF,
CED

2. INTRODUCTION
• Thatch roofing is a traditional roofing method that involves using dry vegetation such as
straw, water reed, rushes, sedge, and so on to create a roof covering.
• It is still used in abundance in some equatorial countries, such as in Fiji where palm leaves are used,
Dominica with feathered palm leaf roots, and Kenya with sugar cane leaf roots.
• In developed countries, thatch roofing has started to become more popular again, as a conscious
design choice because of its aesthetics and for its ecologically-friendly credentials as a sustainable
material.
• The material composition of thatch, with its natural voids and surface irregularities, provides
excellent insulation when dry and compact.
• However, when degraded with an accumulation of moss and rainwater, the insulation properties are
less reliable. Thatch can also be vulnerable to fire.

3. History of Thatch Roofing
• Thatched buildings were very common with indigenous peoples such as the Maya, Inca and Aztecs.
• Across Europe too, wild vegetation was used to cover shelters and primitive dwellings. Straw is
believed to have been used as a roofing material in the Neolithic period when cereal agriculture
began to develop.
• Before commercial production of slate begun, thatch was only commonly available roofing material
until late 1800.
• The use of thatch began to decline towards the end of the 19th century because of the agricultural
recession and the urbanisation of previously rural people.

4. Thatch Materials
• The most common type of thatching material used was straw, depending on the availability of type
of straw in the region.
• This led to a diversity of styles, with different types of roof being characterised by the type of
thatch.
Different types of thatch materials used are:
1) Water reed
2) Longstraw
3) Combed wheat reed

5. 1) Water Reed
• This is the most durable of the thatching materials, with a life expectancy of around 50-60 years.
• When re-thatching with water reed, new reed is fixed directly onto the rafters, starting at eaves level,
with the butts of the stalks exposed.
• Steel or hazel sways hold each layer of reed in place.
• A legget is then used to dress the thatch into shape.
• Water reed are used in wetland areas such as the counties of East Anglia.

6. 2) Longstraw
• Longstraw must be made into yealms before it can be used for thatching. A yealm is a tight, compact
layer or straw which is level at both ends. This straightens and tidies the straw, making it
manageable for thatching.
• When re-thatching with longstraw, existing material will usually only be removed back to a base
coat, before the new straw is fixed using hazel spars. Netting is usually fitted to the whole roof as
longstraw is more susceptible to attack from birds.
• Longstraw roofs are steeply pitched.

7. 3) Combed Wheat Reed
• It is quite similar to water reed, this is a type of straw which has the grain removed using a combing
machine.
• Applying combed wheat reed is similar to water reed. however, the existing material from the roof
doesn’t necessarily all have to be removed.
• Combed wheat reed roofs are shallow pitched

8. Ridges
The ridge of a thatched roof
must be carefully
maintained every 10-or-so
years, as the fixings are
external. The two main
types of ridge are as
follows:
The ‘wrap-over’: Formed
by folding a thick layer of
material over the roof apex
and fixing on both sides.
The ‘butt-up’: Formed by
forcing the butts of the
material together from either
side to form an apex.

10. Performance
The performance of a thatched roof depends on
the roof shape and design, the pitch, the location
of the building (in terms of weather conditions),
the quality of the material, and the skill of the
thatcher.

11. Advantages
of Thatched
Roofs
The natural properties of thatch
have a number of benefits:
• It is naturally weather-resistant.
• It does not absorb a lot of water when
properly maintained.
• A roof pitch of at least 50-degrees allows
precipitation to run off quickly.
• It is a natural insulator, with air pockets that
insulate well in both warm and cold
weather.
• When applied correctly, thatch has very
good wind resistance.
• Thatch is relatively light, meaning that less
timber is required in the roof structure.
• It is a versatile material when it comes to
covering irregular roof shapes.

12. Disadvantages
of Thatched
Roofs
There is the perception that thatch roofing is at
a higher risk of fire, meaning that thatched
houses are harder to insure. Thatched roofs can
also be more expensive than other coverings,
and costly damage can be caused by birds,
rodents and insects.

14. Thatched Roof Fire
Protection
• There are few disadvantages to thatched roofing
as compared to slate, asphalt tiles and other
materials.
• The most significant disadvantage is the fact
that thatch is combustible.
• Once a fire starts in a thatched structure, that
structure is more likely to suffer damage directly
related to roofing materials.
• Therefore, certain precautions must be taken to
ensure the safety of buildings with thatched
roofs.
• The problems don't arise until a fire actually
starts.
• So the goal of thatched structure owners is to
prevent fires from occurring.

15. Precautions
for
Thatched
Structures
Following advice should be kept in mind to significantly reduce
the risks of thatched structure fire.
1. Chimney related (loose embers, etc.)
2. Electrical problems
3. Stove, Burners and Fireplaces
4. Roof Voids
5. External Fire Sources
Contd…

16. 1. Chimneys
Chimneys in thatched structures should regularly be inspected by a
registered chimney engineer to ensure integrity. Any hidden sections
of the chimney should be checked by a thatcher when any work is
done on the roof.
Other safety precautions for chimneys include the following:
• Chimney pots should be at least 1.8m above the thatch
• Chimneys should be swept semi-annually; quarterly when wood
is burned
• Spark arrestors should be avoided in thatched structures
• Liners meeting local regulations should be installed
• Register plates should only be installed with the help of an
experienced professional.
Contd…

17. 2. Electrical
Electrical problems are the second most common cause of fires in
thatched structures. In order to prevent such fires, owners of a
thatched structure should take the following cautions:
• Electrical systems should regularly be inspected to ensure
integrity
• Any and all wiring connections must be spaced at least 30cm
away from thatch and wire netting
• TV aerials and dishes should be installed on poles or gables
rather than attached directly to the roof
• Any overhead electrical feeds should be insulated with ceramic
insulators
• Electrical wiring in the roof space should be contained inside
metal conduit
• Loft space should be protected against rodents that might
otherwise damage electrics
• Light fixtures in the roof space should be enclosed in the
bulkhead; recessed lighting should never be used
• External halogen lights should never be installed close enough
to thatch to cause a fire via heat transfer.
Contd…

18. 3. Stove,
Burners
and
Fireplaces
• Many property owners use stoves, burners and fireplaces for
internal heat. Obviously, such cases present an additional risk
for structure fires.
• A thatcher should be consulted for advice on the best location
for the burner and the safest way to install it. .
• Only a licenced professional with experience should be
allowed to install the burner inside a thatched structure.
• When selecting a new unit, consumers should stick with the
smallest possible unit that will provide the desired amount of
heat.
• In cases where burners already exist, property owners need to
ensure they are in proper working condition AND safe before
lighting a fire.
Contd…

19. 4. Roof
Voids
Roof voids present an extra level of danger in thatched structures
because they tend to be bone dry. It's critical to avoid creating any
sparks in the spaces. Therefore:
• Hot work should never be conducted in roof voids
• Compression or push fittings should be used by plumbers in
these spaces
• Frozen pipes should be thawed with hot water – never a
blowtorch, hair dryer, etc.
• Smoking, candle use, and lighters should all be prohibited in
roof voids
• Lofted areas should be kept clean and clear of clutter in case
there is a fire
• Fire-resistant covers should be used on all access hatches.
Contd…

20. 5. External
Final
Sources
External sources of fire abound, especially in rural settings. Property
owners should be extremely careful with anything external that poses
a potential fire hazard. For example, halogen security lights generate
considerable amounts of heat; they should never be installed within
proximity of a thatched roof.
Additional precautions against external fire threats include the
following:
• Property owners should never start bonfires or use Chinese
lanterns or fireworks on their property
• Barbeques should only be used well away from the structure and
downwind
• Property owners should inform neighbors about the risks of
bonfires, fireworks, barbeques, etc.

22. Fireproofing
Thatched
Materials
There are three kinds of materials they can use to
fireproof thatch:
• Thatchbatts
• Aluminium Barrier Foil
• Fire Retardant Spray
When used in combination, these three products
give maximum fire protection
The Thatchbatts and Foil work by physically
insulating the house interior from the thatch. The
Spray protects the thatch itself with a non-toxic,
bio-degradable, and odorless fire retardant.

23. Thatchbatts
• Thatchbatts are non-combustible, high quality resin bonded
lightweight Rockwool slabs, designed to provide fire
protection to the underside of thatched roofs on new buildings
and/or extensions to existing buildings. They will also provide
thermal and acoustic insulation.
• Thatchbatts are installed between the roof rafters. When used
in conjunction with Aluminium Barrier Foil, Thatchbatts
provide a total fireproof barrier between the thatch and the
house.
• While thatchbatts won't prevent thatch from catching fire from
external sources, they effectively shield the thatch from wiring
and internal sources of fire.
• Most importantly, they provide a wide margin of time to safely
evacuate a thatched building whose roof has caught fire.

25. Aluminium
Barrier Foil
• Barrier Foil acts as both a fire resistant barrier and a thermally
reflective insulator. An added advantage is that, once it is fixed to
the roofing laths, the foil provides a weatherproof covering to the
roof during the thatching operation, thus avoiding the necessity of
using tarpaulins, etc.
• Barrier Foil contains no flammable materials. It is a heavy gauge
aluminium foil specially selected for its combination of strength
and fire resistance.
• The foil is applied in exactly the same manner as traditional roofing
felt.
• When combined with Thatchbatts, the level of protection to the
interior of a building is the highest possible.
• On its own, the Foil provides a high degree of protection, but
evacuation times would not be as long as with the thatchbatt/foil
combination.

27. Fire
Retardant
Spray
There are two types of fire retardant sprays:
Indoor Spray and Outdoor Spray
• The outdoor spray is sprayed directly onto the surface of
the roof.
• Outdoor spray not only provides fire retardant capabilities,
but it is also water repellent.
• Outdoor spray cannot be washed out and is a special
protection against leaching.
• The indoor spray is used on the internal surface of the
thatch and the supporting timbers.

29. THANK
YOU