Lime Plaster Benefits

Lime plaster benefits are many but the most impressive are its breathability and flexibility making it very useful for conservation. In a modern building where this is no movement, flexing, shrinkage or damp then cement based renders and plasters are fine, but older properties that may have many different materials and specifications lime can be more forgiving 


Advantages over cement based coatings:


Breathable


Lime plaster will allow moisture to easily pass through whereas cement will trap and prevent moisture from escaping, leading to a greater problem - gradually building and then ultimately forcing the damp to come out elsewhere. Whilst damp will not rise much more than a metre, it has been reported that damp has been forced nearly 3 metres high into the next floor above due to the cement render not letting any moisture escape.

A damp wall plastered with lime will allow the wall to breathe everywhere and therefore prevent a build up of moisture.


Flexible

Whilst cement based plasters and renders are strong in compressive strenth they lack greatly in flexibility. Any movement can easily result in the very strong cement based plaster cracking and if used externally will allow the ingress of water and damp. Then the damp will be trapped behind a non breathable render. 

Lime whist not as hard is more flexible, so suited for use in an older building. 


Anti Fungal

The alkaline properties of lime are naturally bacteria repellant


Disadvantages of Lime 

Setting and hardening of lime is not an exact science. Cement and gypsum plasters have a standard set and hardening process whereas this process in lime is less predictable and takes a lot longer.


Strength

Lime mortars gradually achieve good compressive strength allowing for movement. 


Compressive Strength after 28 days 

Hydraulic Lime & Sand  (1:1.5)  1.47 N/mm2

Cement, Lime & sand (1:1:6)  7.7 N/mm2


Compressive Strength after 6 months

Hydraulic Lime & Sand  (1:1.5)  5.3 N/mm2

Cement, Lime & sand (1:1:6)  8.1 N/mm2 


Compressive Strength after 12 months

Hydraulic Lime & Sand  (1:1.5) 5.9 N/mm2

Cement, Lime & sand (1:1:6)  8.7 N/mm2



Water repellant yet breathable

Tadelakt is both breathable and hydrophobic