Civil Engineering Reference
In-Depth Information
plate should also ensure that the straw itself
is raised above the finished floor level by at
least 25mm (1”), so that if you accidentally
drop a bucket of water on the floor the flood
won't touch the straw.
Wet ground
This might be badly drained, or flood from
time to time.
•
Stone pile foundations with piers on top.
Tie-downs
•
Timber pile foundations raised above the
ground. (Illustrated on page 64.)
The foundation design will often need
to incorporate some method that allows
for the wallplate/roofplate and roof to be
fastened down securely to it to prevent the
roof from being lifted off by strong winds.
If the roof is heavy (e.g. slate or planted)
or the site is sheltered this may not be
necessary. Methods of tie-down include the
following.
•
Raft foundations of timber, e.g. as in
Winchester cathedral, which was built on
a marsh.
Moving sand soils
As in wet ground, you need to use a deep foun-
dation that carries you below the sand layer.
•
Plastic strapping can be laid underneath
the foundations in a U-shaped plastic
pipe for protection (25mm water pipe
works well). The strapping can then be
carried over the wallplate once the straw
is in position, and fastened in tension
using buckles or similar.
Sloping ground
Any type of pier foundation is suitable here,
or stepped strip foundations.
Other differences in
foundations owing to the
use of straw
•
Strapping can be fixed to the timber base-
plate that is laid on top of the foundations,
as long as the walls are heavy enough to
prevent the baseplate from lifting.
Timber baseplate
Compression
Strip foundations will always have a timber
base plate on top, and pier foundations will
have a structural box beam linking the piers.
These provide fixing points inside and out
for render stop, skirtings, tie-downs, etc.,
and also for short hazel stubs on which the
first course of bales is imbaled(!), preventing
it from sliding off the foundation. The base-
It will usually also be necessary to fasten
temporary compression straps to the
foundations. Some ways of doing this are
as follows.
•
Leave a hole in the foundation through
which a metal pin can be inserted later to
protrude 100mm (4”) from each face, so
