Indicative detailing - The Hempcrete Topic: Designing and Building with Hemp-lime - page 575

Openings that do not have frame loads (joists or rafters) bearing on them need only the
framework to provide a fix for the door or window frame and extra timbers as necessary
to support the weight of the hempcrete. For short spans, these extra timbers might just be
battens as described above, in addition to the door or window framework, but for longer
spans, larger-section timbers or a separate structural lintel may be required to support the
hempcrete. Openings bearing frame loads also require a structural lintel within the frame.
For extra structural integrity in the cast hempcrete at this vulnerable area, the lift of hemp-
crete that goes over the opening (and extends beyond each side of the opening) is placed
in one go to form a cast-in-situ 'lintel' of hempcrete.
Sill details
Windowsills in a hempcrete wall should have a good-sized drip detail on them to take wa-
ter away from the surface of the wall. There are many options for doing this, and airtight-
ness should be maintained using the methods described on page 338 and shown in Figures
36 and 37. Standard aluminium or timber sills can be used (but, depending on the place-
ment of the window within the wall, a longer sill may be needed (see Figure 37(a) and (c) )
or a secondary sill can be placed below it (see Figure 37(b) ) . Natural slate provides an at-
tractive and durable option, and can easily be cut to the required size (see photo below).