The thatch
has to be fastened on to wooden plating of at least 19 mm thick. (because
of the lenghts of the screws used) If the screws are allowed to show
on the underside (for example when insulation is fitted to the underside)
then it is possible to use even thinner plating. All is permitted
as long as a screw will hold when pulled. The underconstruction should
be dry and clean.
The
spacing of rods:
The fist rod
has to be mounted 200 mmm from the bottom.
The second one 120 mm above the first, every next one comes 280 mm
above the last.
The top rod comes 200 mm from the top.
The last but one 200 mm underneath the last one.
(see scetch)
Tilting fillet:
Everywhere where
the thatch is extended over the under construction a barge board has
to be fitted which should stand above the underconstruction about
50mm. The exact dimensions of this depends on the reed used. (the
shorter the reed, the smaller this measurement.
Thickness of the thatch layer:
If the distance
from the top of the roof to the eaves does not exceed 7 meters, the
slope of the roof exceeds an angle of 45 degrees, and reed is used
which is shorter than 1.5 meters, than the thickness of the thatch
layer should be at least 25 cm on the eaves and 22 cm on the top of
the roof. The wear part of the thatch should be at least 10 cm (the
part of the thatch on top of the fastening rods)
All measurements should be taken through the layers of thatch, at
a right angle to the roof construction.
If the distance
is more than 7 meters, or the slope is less than 45 degrees, or reed
is used which is longer than 1.5 meter, the measurements should be
at least 28 and 25 cm. (the minimal layer of wear should in this case
be at least 12 cm.
Lately there is a tendency to make thicker thatched roofs (upto 35
cm)
- surface:
- To determine
the price of a thatched roof, in Holland, the total outside surface
of the thatch is measured.
- Quality
of reed:
- Determination
of the quality of reed is very difficult. The customer should rely
on the professional skills of his thatcher for this.
In the specifications of the roof the origins of the reed should
always be mentioned.
- Fastening
the thatch:
- The reed must
be fastened very firmly to the construction at intervals as shown
above.
The fastening rod must be of galvanised mild steel of a thickness
of 5 mm
The thin binding wire is made of stainless steel
The reed is fastened somewhere between 40 and 55 cm from the end.
- The thatch
should not extend the construction by more than 15 cm.
- Under the top
tiles very often a small band of wire netting is attached to strenghten
the cement and to prevent damage of the thatch by birds.
- lifespan:
- The lifespan
of a thatched roof should be at least 25 years.
This lifespan is depending on many things such as: the sloop of
the roof, the reed used, the skills of the thatcher who made the
roof, and the care and maintenance which it is given.
The minimal slope on which thatch can be applied is 30 degrees above
a small dormer window (absolute minimum) and 45 degrees for the
main roof.
If the thatch is applied to a roof with a sloop less than 45 degrees
one has to be prepared to accept an even shorter lifespan.
(see also the page:
lifespan and
maintenance)
