Lime built structures can tolerate seasonal and minor structural movement without damage to masonry or joints. Any movement is taken up by minute adjustment within the flexible mortar beds over the many courses of brick or stonework. The hairline cracks that may occur can subsequently be resealed by so called autogeneous healing. The mechanism for this is not well understood but may involve continuous carbonation or re-carbonation of deposits of lime out of solution.
'We know from surveys undertaken on buildings constructed in Victorian and earlier periods that where lime mortars have been used, movement and settlement has occurred without major structural damage,' says Lachlan McDonald of Ellis & Moore. These structures he notes can also accommodate greater expansion and contraction due to temperature changes. Moreover cracks that may occur in a lime mortar can also be self-healing due to the relatively slow carbonation of lime.
'So why not use it - it seems the perfect material for the job!'