Finishes for hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 399

Lime finishes
Lime finishes can be used internally and externally, and share the ability of clay, although
to a lesser extent, to buffer moisture in response to changes in the indoor humidity. They
have advantages over clay in terms of cost and convenience of application. Lime finishes
are particularly suitable for use externally, since the re-carbonation of the building lime
gives them a hard finish that withstands weathering while retaining the all-important prop-
erty of being vapour permeable.
Lime plaster in a new-build hempcrete house.
Lime finishes, especially those based on air limes or feebly hydraulic limes, have a unique
ability to reseal small cracks in their surface, should any appear. This is due to the presence
of free lime (lime within the render that has not fully carbonated - see Chapter 3 ). These
particles of lime are free to move around in the render, and when it rains, are deposited in
the crack and then carbonate on exposure to air, sealing up the surface again.
More detailed information on lime plasters and renders is given in Building with Lime: A
practical introduction and Using Natural Finishes.