LIME
Lime has been used as a binder for mortars, renders and plasters in traditional buildings around the world for thousands of years. Today, Portland cement is used as the primary binder in modern mortars and there are important differences between the two, which are in turn important for the conservation, repair and restoration of traditional buildings.
Lime plaster
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Lime plastering onto laths, brick or stone involves a traditional method of creating a durable and breathable finish for interior walls and ceilings. We will try to conserve any existing plaster wherever possible - hollow or detached plaster can sometimes be consolidated and saved, which may be preferable to replacing it, especially if it is very old. Where lime is restored, we will match the texture and profile of any existing lime plaster (for example ‘pillow cushion’ profiles for panel infills). ​
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In all cases, we will make any repairs to the underlying wall, supports or laths to provide a secure base for the plaster to adhere. Broken or perished laths will be replaced where necessary with matched materials (usually oak, chestnut or larch). These can either be sawn or hand riven and fixed using galvanised nails or screws.
Plastering will usually involve applying three coats – base, float and finish coats - each separated by a few days to a week to allow sufficient drying time.
Lime render
​Applying lime render to your home (to exterior laths, brick, stone or daub) follows a similar process to that used for plastering and usually involves applying three coats, each separated by a few days to a week to allow sufficient drying time. Specialist finishes, such as roughcast (where the render contains gravel) may require a fourth coat.
We always try to conserve any existing lime render wherever possible and by carefully matching the existing material we can sometimes repair failed render without the need for complete re-rendering. This includes cracked, hollow, damaged or missing render.
In some instances, where any existing cement render is causing damp problems or is known to be damaging the underlying brick or stone, you may wish to remove it and replace it with breathable lime. We can assess the practicality of doing so and its potential impact on the underlying wall.
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See also our Blog.
Lime pointing
Repointing with lime mortar is a traditional method used for restoring historic buildings or structures. Lime mortar is preferred over modern cement-based mortars for such projects because it allows for flexibility and breathability, which is important for the preservation of old buildings with softer masonry.
Old lime or repointed cement mortar will be carefully raked out (normally to a depth of twice the joint height) using hand tools and, where any damage to the bricks can be confidently managed, mechanical removal with a masonry saw or mortar raking disc (and sufficient dust extraction). The raked joints will be thoroughly cleaned of loose material to help provide a strong bond for the new mortar.
A colour-matched lime mortar will be used to repoint the section of wall. An assessment of the type and strength of lime to be used will be determined by the exposure of the wall and the strength of the existing bricks or stone. Non-hydraulic lime putty is most often used with or without special additives (pozzolans). The pointing will be finished with a joint profile to match the existing wall or flush finished.
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See also our Blog.
Limewash
Limewash is a traditional method of finishing walls, particularly on exterior surfaces of buildings and is known for its natural, matt finish. It provides a breathable coating, allowing moisture to evaporate. This is particularly beneficial for buildings built using traditional construction methods where breathability is essential to prevent issues like trapped moisture and decay.
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It is not uncommon to see modern masonry paint applied over the top of old, existing limewash. If this is the case for you, we would need to remove the paint layer before applying the wash.
A minimum of 3-4 thin coats will be applied, depending on the surface, with ideally 24 hours between each coat to allow enough time for the wash to cure.
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Limewash requires maintenance over time, as it can gradually wear off or be affected by weather conditions - typically requiring renewal every five years.