The structural frame - The Hempcrete Topic: Designing and Building with Hemp-lime - page 271

For the most part, roof design options for a hempcrete building are no different from those
for conventional construction. The only difference in roof structure that often applies to
hempcrete buildings is a long roof overhang at the eaves for additional rain protection,
which is achieved using longer rafters or additional bolt-on rafter ends, as described in
Chapter 22 .
Practical considerations relating to the frame
At the frame design stage, it helps to think about the later stages of the build and to give
some thought to practical issues that are likely to come up in the construction process. A
few examples are outlined below.
When constructing a frame, consider the easiest way to go about it. Decide in advance how
each section of the frame will be constructed and erected on-site, and whether temporary
supports are needed for one section before the next can be put in place. Temporary braces
can easily be screwed into the frame and removed again with no concern about marking
the frame timbers, as these will be buried in the wall or covered with plaster, render or
cladding.
It is possible to prefabricate large sections of the frame on the floor and lift them into place
to be fixed in one go rather than lifting each individual timber into place, thus eliminating
the need to both support and fix each timber at the same time.
Another approach that can make framing faster, if your design allows it, is to prefabricate
the frame in sections in the workshop and bring it to site to be assembled. The main ad-
vantage of this is that the frame construction can be done more efficiently and quickly in a
dedicated workshop, with machine tools, than among the relative chaos of a busy building
site. It also means that the framers spend less time on-site, and it allows the frame to be
quickly assembled as soon as the plinth is ready.
As noted earlier, it is important when designing the frame to consider the process of pla-
cing hempcrete evenly around the timbers, and how this will be affected by the frame
design. As far as possible, the design should avoid creating areas that are hard to reach.
This is why it is useful to minimize the use of horizontal timbers.