Search results
Results from the WOW.Com Content Network
Cement render or cement plaster is the application of a mortar mix of sand and cement, (optionally lime) and water to brick, concrete, stone, or mud brick. It is often textured, colored, or painted after application. It is generally used on exterior walls but can be used to feature an interior wall. [1]
A stone wall in France with lime mortar grouting being applied. Right: unapplied. Centre: lime mortar applied with a trowel. Left: lime mortar applied and then beaten back and brushed with a churn brush. Lime mortar or torching [1] [2] is a masonry mortar composed of lime and an aggregate such as sand, mixed with water.
It allows the building to 'breathe' – as lime is porous, it allows for the collection and evaporation of moisture. Portland cement in contrast, an often applied render for stone or brick buildings, traps moisture behind the stonework, which can result in the erosion of the masonry. [2] A lime render may be covered by a lime wash.
Lime used in building materials is broadly classified as "pure", "hydraulic", and "poor" lime; [11] can be natural or artificial; and may be further identified by its magnesium content such as dolomitic or magnesium lime. Uses include lime mortar, lime plaster, lime render, lime-ash floors, tabby concrete, whitewash, silicate mineral paint, and ...
In two coat render a base coat is applied with a common mix of 4 parts sand to one part cement and one part dehydrated lime and water to make a consistent mortar. Render is applied using a hawk and trowel and pushed on about 12 mm thick to begin.
Lime is almost as good in balancing humidity as clay. It prevents moisture accumulation inside the building as well as in the wall by its excellent permeability, and is more elastic and workable than cement render. Lime itself is usually white; color comes from the aggregate or any added pigments.
In Economy Village, the rear and middle wythes of brick dwelling walls are laid in a clay and sand mortar with the front wythe bedded in a lime and sand mortar to provide a weather proof seal to protect from water penetration. This allowed a rendering of clay plaster and setting coat of thin lime and fine sand on exterior-walled rooms.
It is usually not recommended to replace more than 20% of the lime content with cement when rendering the facade, and it is a matter of contention whether adding any concrete is ever appropriate in order to maintain the benefits of lime over concrete. Lime plaster is permeable and allows for the diffusion and evaporation of moisture.