All the information below can be viewed in more depth at our specialist pebbledashing information website.

Decorative Aggregates have been producing quality products for the construction and refurbishment industries since 1984. In addition to our extensive range of decorative aggregates we produce dried and industrial products as well as pebbledashing or dashing aggregates. We are able to produce grades and mixes that our customers require and to meet their exacting specifications. To do this we continually invest in the latest production facilities to ensure our range is up to date and fulfills customers requirements.

Dry-dashing or Pebble-dashing products are also known by other names such as Roughcasting or Harling. The use of aggregates applied to the external walls of buildings is a practice that has been around for hundreds of years. The ability to protect the external walls of buildings from all extremes of weather has always appealed to architects and builders who want a long lasting appearance that will extend the life of the building. We have pioneered the washing, blending and bagging of aggregates that gives a range of colours that is unrivalled and meets the most demanding customers requirements.

Application Guide Summary

We have prepared a guide to give all parties involved in the application of dry dashing aggregates an indication as to the correct way to use the products. This guide will only deal with issues relating to the aggregates being used and will not attempt to offer guidance or advice regarding the render that they are being applied on to. The current British Standard Code of practice for External Renderings BS EN13914-1:2005 offers little guidance regarding the specific process used to apply dry-dashing and this document is intended to provide good practice methods that when used on all applications will reduce the likelihood of problems. By working with contractors, system designers and specifier’s our range has developed into the most comprehensive set of products available.

Our detailed Application & Product Guidelines are available at our pebble dashing information website and refer to applying pebble dashing on to render. The website contains the following subjects:-

• Handling
• How aggregates used for dry-dashing should be supplied and handled.
• Preparation of Background
• How backgrounds to be rendered should be examined for contamination, deterioration, surface roughness, suction and strength.
• Application
• How to mix the dashing prior to application.
• Production
• How the product is selected from reliable and consistent quarries and prepared for use.
• Uneven Appearance Due to Lime Bloom
• How cement based renders can display lime bloom and how best to avoid it..
• Uneven Appearance and Irregularity of Surface Texture
• How uneven towelling and application of chippings can cause patchy appearance on walls.
• Temporary Protection of Dashed Elevations
• How to use temporary protection of the elevation when scaffold is used to apply dashing aggregates in poor weather.

Rendering Defects – What Can Go Wrong?

• The main culprits in render defects are:-
• Bad Materials
• Bad Mixing
• Bad Substrate
• Bad Application
• Bad Design
• Weather

Other examples based on wide experience of defective render surfaces can include:-

• Heavy spalling
• Light spalling
• Delaminating
• Heavy Cracking
• Light Cracking or fissuring
• Balding
• Friable Surface
• Wrinkled Surface
• Lift Marks
• Scud or whip marks
• Bleaching or Patching
• Rust Staining

Rectifying Problems with Render Application

The long term effectiveness of any treatment requires the correct identification of the defect and the removal of the source of that defect be it bad design or workmanship. Removal of the defective material if required and effective preparation of the substraight. There are three courses of action that are appropriate:-

• Patching
• In many cases this would be the most economic solution in the short term.
• Re-rendering
• This can be an effective long term solution.
• Overcoating
• This requires the application of a supplementary coat/s of render on top of the existing render finish.

Also covered in more detail on our Trade Application Guide page on our specialist indepth Pebble Dashing website are:-

• Preparing Surfaces for Rendering
• Render Mixes
• Rendering onto masonry substraights
• Pre Mixed Dash Receiver