Lime has been used as a wall coating for hundreds of years because – if applied correctly – it literally becomes limestone again once it has cured. Lime plaster is more scuff resistant and water droplet resistant than clay plaster without sacrificing much vapor permeability. Lime does require a fair amount of energy to process (though not as much as Portland cement). Also, it can be tricky to work with in dry climates as it needs a constant level of moisture over a long drying time to cure properly. Lime plaster is more difficult to repair than clay plaster but is more durable.
Lime plaster is also a good choice for straw bale walls because of its vapor permeability. Lime does wick water, so consideration needs to be given when using it as an exterior plaster. We recommend using a clay &/or clay-lime base to help protect the substrate from wicked water.