Outline specification : plastering, rendering, masonry and pointing

Product Description

Unilit 40 is a traditional, dry premixed mineral water-repellent finishing mortar based on natural hydraulic lime as the binder and appropriate well-graded aggregates.

Unilit 40 is characterised by a slow but strong bonding, a high plasticity, a low content of soluble salts and an excellent water vapour permeability. 

The natural hydraulic lime mortar is inherently stable and designed to reduce problems of micro cracks along with premature drying out. 

Unilit 40 is perfectly water-repellent and, hence, performs perfectly where rising damp and capillary action is prevalent.

The natural hydraulic lime binder, used to prepare the preblend, conforms to the European Standard EN 459-1, NHL 5 for building limes.  The mortar Unilit 40 conforms to the European Standard UNI EN 998-1.

Application Area

Unilit 40 can be applied as a finish wherever, both from internally and externally, an important exposure to moisture is present. Due to its physical properties, Unilit 40 prevents the direct moisture transfer through the finishing layer, while its optimum vapour permeability allows humidity present in the wall to be able to rapidly migrate from the structure beneath.

Unilit 40 can be applied as a fine finishing layer or thin pointing (joint widths up to 5 mm) in order to protect the background from direct rain water penetration and/or to strongly diminish colour differences within the finish as a result of humidity gradients within the background.

Unilit 40 can perfectly be applied in new construction, renovation as well as restauration, both internally and externally.


Prior to application, the substrate must be cleaned and freed of all traces of oil and grease. The substrate benefits from being slightly dampened. Saturation of the substrate is not recommended, as this will influence negatively impact upon the bond of the hydraulic lime mortar to the substrate as well as the aesthetic appearence.

The mortar is mixed with clean water at a ratio of 4 to 5 litres of water to a bag of 30 kg ready mixed natural hydraulic lime powder. Mixing is undertaken with a slow speed electric paddle for a period of 3 to 4 minutes.  A creamy workable mortar is obtained, which has approximately 2 hours of open time.

When used as a fine finish the mortar is applied in two passes, fresh on fresh, at a total thickness of about 5 mm and consequently sponged, flattened or polished with a trowel to achieve the desired finish. When used for thin (re)pointing  the mortar is applied with a small pointing iron and pressed firmly within the joint. At the end the masonry surface is cleaned with a soft brush in order to remove all excess mortar remains.

If desired, a coloured finish can be applied afterward with a mineral paint, either a lime wash or either a silicate paint. A drying period of 1 to 2 days must be respected.

The mortars must not be applied at temperatures below +5°C nor when a risk of frost exists. They should never be applied on to a frozen surface or in the case of thick fog. In hot, windy and dry conditions measures should be taken to prevent accelerated drying out of the freshly applied mortars. Applied mortars must be protected from frost and direct sunlight for 48 to 72 hours after their application.

Download the PDF version