Hemp lime masonry is as useful in building renovation as in new construction. It is much more flexible than cement and it has proven to be a robust building material with very little shrinkage.
It adheres to steel, brick, concrete, wood and old plaster or render. It can be cast against old stone, brick or cob (earth) walls either on the inside or the outside, and readily goes onto uneven surfaces.
Often used in conservation work in Europe and the UK, the material is demonstrating that it has major potential as an insulating plaster in renovation of buildings where other materials may not cope with the dampness in old walls. It can be used as infill for very small sections or for whole walls. The flexibility and the lack of cracking can ensure that the walls remain airtight.
Retrofitting is done by attaching temporary studs to the existing surface, as in new building. The formwork is attached to these studs. Dependent on the thickness of the walls, if necessary once the wall section has been completed, the studs can be removed and the gaps filled with hemp lime material.
On old buildings that do not have an attractive finish the material can be applied to external walling and then rendered. It insulates the existing thermal mass. It is equally effective when used instead of dry lining on damaged internal walls because it ensures that there are no cavities and retains breathability.