This article is part of our series of How To Paint Exterior Renders, including sand and cement render, lime render, and pebble dash.
An Introduction To Pebble Dash Render
Pebble Dash is a decorative exterior masonry coating applied to a wall using a wet mortar with pebbles (or spar) cast onto it. Traditionally, the mortar used in pebbledash was lime based, but in more recent times cement is the main mortar used. Since the 1990’s a polymer-cement mortar has been available offering a wide range of colours for the mortar layer. Each different product has its own attributes giving advantages and disadvantages.
Nowadays, Pebble Dash is actually what is called Spar Dash. It is very similar to Pebble Dash, in fact it is applied in exactly the same way.
Depending on where about in the country you are, buildings tended to have different aggregate depending on what was available. For instance if you were near the coast, you would often get more smoother, more rounded aggregates that had been quarried from the sea. Whereas areas such as where flint is the predominant stone the aggregate would tend to be sharper, due to the way that flint splits.
The difference between Pebble Dash and Spar Dash is the aggregate material. Where Pebble Dash obviously uses pebbles, Spar Dash uses materials such as chippings, gravel substances and shale. The individual sizes vary from around 3mm to 25mm and are available in almost any colour. You can blend a combination of colours together to achieve flakes or highlights within the wall finish. There are 3 main types of pebble dash coating used in the UK: wet dash, tyrolean and harling. Wet Dash (or Roughcast) is made of Spar or chippings that they mix into the final coat of mortar. You then cast the mix to spray onto the wall.
Pebble Dash Render In Modern Times
This is a traditional finish found all around the UK. However, it has generally fallen out of favour in recent times. Tyrolean or Stucco is a traditional finish mainly used in England and Wales. You can apply it using a Tyrolean gun. You build it up in several layers until you achieve the finish you desire. Tyrolean is good for decorating walls with existing old or poor condition brickwork. Harling is also a traditional finish, applied mainly in Scotland and Ireland. Harling was traditionally a Lime based product cast onto the wall via a flicking method. This involved layering the Lime until reaching the desired effect. This method is also useful for covering up poorly maintained walls or old brickwork.
Recommendations From Our Technical Team
A traditional pebble-dash finish has the surface blinded out with a dense aggregate. This aggregate is generally non-porous so would require an adhesion primer to help paints successfully bond and adhere to the substrate. To achieve an excellent bond, we recommend first priming the substrate.
Rust-Oleum Murfill Waterproofing
An excellent painting system for pebble dash is Mathys Rust-Oleum Murfill Waterproofing Coating. This coating is extremely water repellent. It also holds approval by Trinity House for application on to lighthouses. It comes with a 10 year guarantee if application is correct. A primer of Rust-Oleum Noxyde Anti Rust Cladding and Steel Paint thinned by 20–25% with fresh water. Apply a coat at a cover rate of 0.4 kg per m2, on completion, allow to cure overnight.
Glixtone High Performance Masonry Paint AC1
AC1 Smooth Masonry Paint is a high performance, water based paint coating, designed for use on new build housing projects and over existing masonry paints. AC1 offers Anti-Carbonation properties that provide outstanding level of resistance to carbon dioxide and other acidic gases with a life expectancy in excess of 30 years. Highly resistant to UV rays, oil, grease, alkali, salt & dirt.
Do you require further advice and guidance on how to paint pebble dash render or other renders? Do not hesitate to contact our technical team on 01462 421 333. Our technical team can advise on all aspects of your project and specify the best performing paint system based on your individual requirement.