Different Types of Lime Mortar

The lime binding component used in construction mortars, can be broadly categorised into two types, Natural Hydraulic Lime (NHL) & Non-Hydraulic Lime.


Which mortar to use

When mixed with aggregate and water, these different lime components produce two, noticably different  lime mortars.

The main difference between the two is the speed in which they set, gain strength and therefore, their preferred applications.

Note! Typically, if a lime mortar has been specified or there has been reference to NHL (eg. NHL3.5 or NHL.5) a Hydraulic Lime Mortar is required. View Our Construction Mortars

Hydraulic Lime Mortar

Suitable for conservation, restoration works and 'New-Build' construction. 

Hydraulic Lime Mortars are made using a binder of Natural Hydraulic Lime (NHL). 

The initial chemical set of a Hydraulic Lime Mortar, makes it suitable for the demands of modern day construction, allows for a similar build rate to that of a cementious mortar but also suitable for restoration works or when working within historic surroundings.


Non-Hydraulic Lime Mortar

Commonly referred to as ‘Fat Lime’ or ‘Lime Putty.' 

Mainly used for very specialist restoration and conservation works. It does not have an intial 'set', is softer and sets very slowly, by carbonation only. 

For this reason, it is limited in its use and not ideally suited to 'new build' construction.

* Limetec do not manufacture or supply Non-Hydraulic Mortars. 

Lime Components / Binding Agents Explained

Abreviations and the noticable similarity between 'Non' and 'Natural', means they are often confused.

Natural Hydraulic Lime (NHL)

Hydraulic Lime is a general term for varieties of lime which set through hydration. Made from limestone that contains natural silicates, these silicates create an initial chemical ‘set’ when mixed with water and then, continues to gain strength, through carbonation.


* Natural Hydraulic Lime is the component used in all Limetec products.

Non-Hydraulic Lime

Non-hydraulic lime is made from pure limestone, pure calcium carbonate. It sets by carbonation only, absorbing carbon dioxide from the atmosphere and because of this, takes a long time to set. Non-hydraulic lime comes in two forms, a dry powder and a putty. 


* Limetec does not supply these products.

“Natural Hydraulic Lime is perfectly suited for new build and can play an important role in the future of modern construction”