Cruck frames are a very early and
simple form of building a timber framed house. First one has to find
a tree (or a very large branch) which has a natural curve. This curve
must be in one direction only, i.e. it must not start curving upwards
and then go off to the left or right; a banana shape one might say.
The tree is then sliced down the middle to provide two similar pieces
of wood of the same, but complementary, shape. By placing the ends
on the ground (say) 20' apart and the other ends together (say) 20'
in the air, an arch shaped structure is formed. This provides a frame
which will support the roof and walls of a building.
To make a complete building, more trees of similar shape and size
are required to make a number of cruck frames. For example, 5 cruck
frames would make a four bay building. A large tree may provide 2
pairs of crucks. The two
parts of a cruck frame are known as the blades.
Various other timbers are added between the blades depending upon
the position of the cruck frame within the building. For a gable,
provision must be made to support the external wall (wattle and daub?),
and for the centre of a large room (a hall for example), only timbers
to strengthen and enhance the cruck are required.
Finding suitable trees from which to make crucks is not easy as there
are a limited number which have grown over hundreds of years with
an even curve. They were also much in demand for ship building (used
the other way up!) For this reason the cruck frame method of construction
gave way to the box
frame which only required straight lengths of timber.
to see a drawing of a cruck frame
This is a drawing of an old one that we will use.
here to see an example of a box
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