The
closed construction
"the screw roof"
Using this
construction the reed is screwed onto a flat wooden surface.
(see daigram)
The wooden sheet material (19 mm thick because of the length of the
screws) can be a triplex or plywood, underlaying or whatever as long
as it is pressed in a way that the screws will not be pulled out.
The layer of air underneeth the thatch is non-existant. The whole of
the thatch is helping to make a 30 cm thick layer of insulating material.
The roof will not allow any draft.
There is a definite division between outside and inside.
Fire in the thatch cannot draw oxygen from untherneath , the fire will
smoulder more than it will burn, and even when it burns, it burns not
as fiercely and it will burn on the outside where the fire department
or a neigbour with a garden hose can extinguish the fire quite easily.
In Holland such a roof can be insured for the same price as a house
with tiles.
 
Even
before the roof is thatched the roof is closed already.
From the inside one can see that a fine finish is obtained for free.
If a better insulation is wanted one can buy sandwich panels or box
panels which are specially made in Holland for the thatched roof.
for more info see also specifications
screwroof
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