Placing hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 367

When the surface has dried sufficiently, finishes can be applied.
The way to tell whether the wall is sufficiently dry for the application of finishes is to en-
sure that there is a consistent dry crust on the surface of the wall, to a depth of around
40mm. This indicates that the wall has dried to the extent that water is now reaching the
surface of the wall only as moisture vapour, rather than liquid water droplets. Tannins only
dissolve in liquid water; they are not carried by moisture vapour, so once this stage is
reached you are safe to apply renders and plasters without the risk of staining.
The time taken for hempcrete walls to dry to this point varies depending on a number of
factors: the type of binder used, the thickness of the wall cast, local weather conditions,
good mixing technique (limiting the amount of water that goes into the mix) and good dry-
ing management once walls have been cast. The 'normal' time before finishes can be ap-
plied is around 6-8 weeks, depending on the binder used and of course on the thickness of
the wall.
When planning the build schedule, 6-8 weeks after casting should be considered the earli-
est time at which finishes (especially wet finishes) can be applied to a wall of 300-350mm,