Design fundamentals - The Hempcrete Topic: Designing and Building with Hemp-lime - page 525

will dry out the surface between periods of wet weather. On a north-facing wall, however,
where insufficient sunlight falls to have a drying effect between rainstorms, then a render
finish may prove too permeable and the accumulation of moisture in the wall too great.
In this case, the solution will probably be to use a cladding finish with a vented air gap
between the cladding and the face of the hempcrete wall. Cladding might take the form of
a wooden screen, stone or brick masonry with lime mortars, or hung slates or tiles over
wooden battens. As well as the level of protection offered by the cladding material, con-
sider the likely level of maintenance required by the cladding itself in the particular situ-
ation. For example, wooden screens in highly exposed situations will need far more main-
tenance, through the application of protective oils or paints, than would stone masonry or
hung slates.
Site-specific effects on wall thickness
In some instances it may be appropriate to vary the thickness of the walls around the build-
ing to cope with extremes of temperature on differently exposed elevations. In our exper-
ience this is rarely done, but it may be quite sensible, for example, to make walls thicker
where they were exposed to excessive sun or to cold winds. This particularly applies in a
building for which thinner-than-standard hempcrete walls are being specified.
Site-specific effects on roof and plinth
This is to some extent self-evident: in areas of high rain or snow, consider increasing the
overhang of the roof and the height of the plinth, in order to reduce the amount of water
that comes into contact with the face of the wall. By the same token, a good-sized roof
overhang, or the continuation of the roof into a covered cloister or walkway around the
edge of the building, can help with shading exposed walls of the building in very hot
climes.