Civil Engineering Reference
In-Depth Information
From accurate bale plans you can work out
how many bales you need, as well as how
many hazel stubs (two per bale on the first
course), pins (two per bale for the fourth and
sixth courses), staples (in every bale where
it changes direction, e.g. corners) and other
quantities of materials. Details of foundations,
windows, first floor and roof can be worked
out.You also now have the basis for drawing
your own plans for planning permission.
number of bales or half bales, thereby
reducing the labour time involved in
customising.
In a loadbearing design the walls will settle
a bit once the weight of the roof is on, or
after you have done the pre-compression,
so allow for this by leaving gaps above
windows and doors that can be filled in later.
With construction-grade bales, settlement
in a seven-bale-high wall should be about
70mm (2¾”); for less-dense bales you need
to allow for more settlement than this, unless
you have a lightweight roof.The amount of
settlement depends on the density of the
bales and the amount of loading applied to
them (such as the weight of the roof, whether
there is more than one floor, etc.).
Principles of bale design
and layout
•
Before you draw your final plan, and
before you finalise the dimensions and
lay out the foundations, you need to
know the dimensions of the bales you
will be using, as they can vary a lot!
Interestingly, some of the laboratory tests
done to find out how much load strawbale
walls can carry have appeared to show that
only single-storey houses can be built this
way. This is patently not true in practice!
We need to be very careful when looking at
research findings and especially when talking
to engineers, as they are often not very
familiar with strawbale building in practice
and may test or calculate for situations
that turn out to have no relevance to actual
performance. Common sense and practical
experience should be our guides. After all,
it was engineers who proved that a bumble
bee cannot possibly fly . . .
•
The bale plan should be made up of a
whole number of bales wherever pos-
sible. Any half bales should be only at an
opening.
•
Do not have any places in the wall (e.g.
beside a window) that are less than half
a bale in length.
•
Window and door openings must be at
least one bale length away from corners
in loadbearing designs.
•
If at all possible, choose window and
door sizes that, together with their framing,
are multiples of bale dimensions.
•
Try to design frameworks so that the dis-
tance between posts is equal to a whole
