Positively Dashing
29/11/2005

Zack Barrett, Marketing Manager at Brett Landscaping and Building Products, discusses the re-emergence of a traditional façade finish.

Used only for building refurbishment for too long, dry-dashing is enjoying something of a renaissance of popularity amongst specifiers: it is increasingly being seen as a surface finish of first choice for a number of reasons relating to both its acknowledged cost and performance benefits and a renewed interest in the aesthetic finish it can provide.

The process of dry-dashing involves the use of quarried aggregates in combination with a surface render. In most cases the aggregate finish is left bare, allowing the natural appearance of the stones to provide the primary aesthetic appearance of the façade. The colour of the stones will, of course, vary depending on their source: the most popular by far is Durite Canterbury Spar which gives the familiar brindled appearance, although other aggregate types with their own colour variations are also available.

A contemporary twist can be added to the appearance by using a coloured backing render that will either accentuate or contrast with the colour of the aggregate to give a unique appearance. The surface will not require painting, of course, and the facets of the quarried calcined aggregates give a high solar reflectivity that helps the façade to maintain its bright appearance.
The natural durability of the aggregates is not in question and the surface will weather over time just like any other natural stone. The only possible additional consideration for the choice of aggregate would be to consider a low-absorption material as a first choice in areas with potentially high levels of airborne pollution to ensure that pollutant particles simply wash off in the next rain shower.

The choices of both aggregate types and render colours allows specifiers a huge choice of visual effects and it is probably an awareness of this choice that is giving dry-dashing its renewed appeal – other characteristics of the process have not changed, but support the use of dry-dashing in a range of applications.

The most important of these, and particularly for volume house builders, is probably cost: including both the initial application stage and the cumulative costs over the lifespan of the building.

During the construction phase, dry-dashing in the hands of a professional renderer is a quick finish to supply and is a forgiving surface. Smooth render finishes need absolute precision in both the original structure and the application – any imperfections will be instantly obvious and any slight unevenness in the underlying material will be highlighted. The application of dry-dashing aggregates to the render solves all of these problems by providing a surface whose very randomness conceals any minor imperfections in the surface of the building.

Naturally this handy characteristic has always made dry-dashing a popular choice for refurbishments, allowing an aging façade to be given an immediate and long-lasting face-lift without the costs involved in re-pointing brickwork or repairing cracked or weathered renders.
Once installed, the dry-dashing requires very little ongoing maintenance. Usually the surface will not be painted and will not need to be specially cleaned.

 

The uneven characteristic of the surface is also a good deterrent to graffiti artists, as the satisfaction of spraying the mottled surface of an aggregate finish does not compare to the impact achieved by defacing a flat white render. For areas with really determined vandals, however, it is now possible to buy aggregates with anti-graffiti resin-based coatings, allowing and surface defacement to be removed easily and quickly.
A good recent example of the use of dry-dashing illustrates many of the advantages of the system.

 

Carrick Housing in Cornwall improves and manages council housing on behalf of Carrick District Housing and, as part of its rolling repair programme, has recently refurbished some 50 houses using Durite Canterbury Spar and Black and white Spar dry-dashing aggregates from Brett Landscaping and Building Products.

Summing up the reasons for the specification of this finish, Planned Maintenance Manager Simon Waters observed: “Our aim was to improve the insulation quality and appearance of the council’s housing stock which has involved upgrading the existing rough cast render finish with more attractive and long lasting dry-dashing. The result is a vast improvement that will reduce ongoing maintenance.”

Similar motives led to Flintshire County Council specifying dry-dashing for the upgrading of thirty-six houses across Baggilt, Holywell, Shotton and Abermoddu. In this instance the Durite Canterbury Spar was chosen particularly because its natural, weathered appearance allows the renovated facades to blend well with the appearance of existing properties.

While the aesthetic properties were clearly an important consideration for both these projects, it is also worth noting that the dry-dashing finish is increasingly being used in partnership with a range of insulating renders. With the steadily increasing pressure on housebuilders to improve the thermal insulation of external walls, we are beginning to see experimentation in the UK with alternatives to the traditional brick and block construction.

As timber framed and other pre-fabricated systems become more popular there is a new acceptance of alternatives to a traditional brick façade. We believe that the next fifty years will see an increased use of rendered exteriors of all types and that brick will no longer dominate the housing landscape and that introducing variety into the urban environment can only be a positive move. The imaginative and creative use of aggregates in dry-dashing surfaces will make an increasingly positive contribution to the appearance of housing in all sectors, while also offering the cost effective life cycle demanded by today’s specifiers.

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