Conservation & Rendering Specialists
Hot lime or Common lime rendering
WALLS NEED TO BREATHE
Lime is the principal binder of traditional mortars, plasters and renders. It tends to be neglected in modern building practice, but it is central to successful maintenance and repair of traditional buildings. Traditionally-constructed masonry buildings used permeable materials such as stone, brick or cob (dried earth) in conjunction with permeable mortars and sometimes renders to keep out the weather. Moisture is both freely absorbed by these materials and released by evaporation from their surface. Damp is kept under control and prevented from reaching the interior by the dept of the wall and by the rate of evaporation.
Traditional materials are notoriously difficult to fully weatherproof, even by the application of modern materials such as silicons. Any impermeable coating such as a paint, cement render or sealant inhibits the ability of the surface to breathe and prevents evaporation, causing damp in the interior, and in time it is inevitable that it will crack, flake off or break down, allowing further moisture penetration to compound the problems. Any attempts to weatherproof a traditional wall is therefore pointless. A permeable render provides far more effective protection.
Lime mortars used as the bedding material for masonry and for pointing the joists provide a permeable route for the passage of moisture from the core of the wall to the surface where it evaporates. Where the stone is very hard and impervious, this may be the only route available. Where the stone is relatively soft, a more porous mortar will always be preferred to reduce the amount of evaporation which takes place through the stone.
Hot lime or Common lime rendering video demonstration.
WALLS NEED TO ACCOMMODATE MOVEMENT
Traditionally-built masonry walls work in an entirely different way: they are much more flexible and will accommodate minor structural and seasonal movements by minute adjustments over many joints. Hairline cracks in the mortar may subsequently be resealed by the precipitation of lime.
Cottage rendered using traditional materials
Hot Lime lime Render.
Natural hydraulic lime Render.
Church of the Rath, Killashandra Co. Cavan, Vaulted ceilings rendered
Using goat hair.
Using goat hair with lime,