Pebble dashing, also known as dry dashing, is a type of finish where pebbles are partially embedded in the mortar used to cover exterior walls of a property. The pebbles help protect the wall against the elements and are available in a wide range of colours and sizes. Pebble dashing requires less skill than regular plastering because the stones help to cover up many imperfections in the final coat of render.
Prepare the surface of the wall by using a wire brush to ensure it is free from any loose imperfections or debris like old paint or render. Remove any organic material and apply a fungicidal wash.
Pour the dry render for the undercoat in a wheelbarrow or large bucket. Add the required quantity of water and mix until you achieve the consistency of a smooth paste. Lightly dampen the wall with water before beginning to apply the render.
Load the hawk with render using a trowel. Transfer some of the render to a steel float and then, using a gentle sweeping motion, slide the render onto the wall covering no more than a metre width each time. Each new application should slightly overlap with the first. Ensure the render is no more than 10mm thick. Use the float to blend the render until you have a smooth finish. Use a scratch comb to score the surface to provide a good key for the topcoat. Allow the render to dry completely, a process that could take up to a week.
Mix the dashing render with the recommended quantity of water. Spray the wall with water before applying the dashing render over the basecoat to a thickness of between 8mm and 10mm.
Place tarpaulins or plastic sheets on the ground beside the wall. Ensure the pebbles are clean and free from dust before half-filling a bucket with them. Using a trowel, scoop some of the pebbles and flick them towards the wall with an upward motion so that they stick into the wet render. Try to make each flick cover as wide an area as possible so that the coverage is even. Continue until the entire wall is covered. Any pebbles which do not stick will be collected by the tarpaulin and can be reused.
Press a wooden float against the pebbles to make sure they are firmly bedded in the render.
The thickness of the final coating will vary according to the size of the pebbles you wish to use. It should not exceed 10mm and should be slightly less than the largest pebble being used.
Pebbles that have been thrown against the wall but not stuck may need cleaning before they can be used again in order to remove any traces of render.
If using more than one bag of pebbles, mix them together beforehand for greater consistency of colour.
To prevent young children from picking out and swallowing stones from a recently completed wall, ensure the pebble dashing begins at least 1m from the ground.
Keep the surface of the render slightly damp while it is drying out. This will help prevent it from cracking.