External Rendering

Textured render finishes

Ashlar detailing provides an aesthetically pleasing effect within the render finish and is achieved by cutting recessed joints into the “green render” using simple tooling. The effects can be quite stunning but good execution by the applicator is paramount and Parex will offer training and advice when this is required.

There are some basic rules with regard to Ashlar cutting that should be observed. These are regarded as good building practice and are detailed below.

  • Total render thickness in one pass should not exceed 25 mm.
  • There must be a minimum thickness with regard to exposure. In most conditions, the Ashlar cut will vary between 5 and 10 mm. Minimum depth of render at lowest point should be 15 mm.
  • For severe exposure, a minimum depth of render at lowest point should be 20 mm.

In the late 1700’s, builders started using rendered finishes on almost everything as bricks were expensive but instead of leaving a plain surface, many buildings had lines drawn onto the part-dried render to imitate more expensive stone blockwork (i.e. ashlar blockwork which meant a dressed cuboid stone with close fitting joints, a classical style originating in Ancient Greece) – and the practice remained common until the late 1800’s.

Trying block marking a few times and recreating a period feel on older buildings requires you to be as consistent with something like a 9 inch x 15 inch minimum block size, and keeping the verticals and horizontals on the level to ensure smooth progress on rendering. Ashlar cutting looks particularly good when painted (use a satin finish external covering) although the extra detailing means that quite often this isnt necessary. The illusion of masonry joints was sometimes enhanced by a thin line of white lime putty, graphite or some other pigment.

Other textured finishes are the English cottage finish (a traditional external finish), adobe and Spanish, pebble-dashed or dry-dash surface, fan and sponge texture, reticulated and vermiculated, roughcast (or wet dash) and sgraffito.

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