How to paint pebble dash

Pebble dash, sometimes called dry dash, is a render finish with small stones pressed into the surface while it is still wet. It is found on a huge number of Irish houses, from 1960s bungalows to estate homes, because it is durable and sheds weather well. Left unpainted it weathers to a mottled grey; painted, it can look fresh for years. The rough texture, though, makes it slower and more awkward to paint than smooth render, and preparation is critical.

This guide covers checking pebble dash for problems, cleaning and repairing it, choosing paint, and the techniques that actually work on a rough surface.

Should you paint pebble dash?

Unpainted pebble dash in good condition does not need painting to protect the wall; the stones and render already do that job. People paint it to change the colour, freshen a stained or patchy surface, or match an extension. Once painted, it will need repainting from time to time like any painted wall, so it is a commitment. If the dash is already painted, keeping it painted is the norm.

Step 1: Check the condition

Paint will not hold loose material together, so start with a careful inspection of every wall:

• Loose stones: rub a gloved hand over the surface. A few stones coming away is normal; a shower of them suggests the dash is breaking down.
• Hollow areas: tap the wall gently with a hammer handle. A dull, hollow sound means the render has come away from the wall behind (blown render).
• Cracks: look around windows, doors and corners, and along the line of floors.
• Damp and staining: often below gutters, sills and downpipes.

Small loose or blown areas can be cut back and patched. Extensive blown render, bulging, or cracks that run through the wall need professional assessment before any decorating, as painting would only hide a problem that is getting worse.

Step 2: Clean the walls

Algae and mould grow readily on the rough surface of pebble dash, particularly on north-facing walls in the damp south-west. Apply a fungicidal masonry wash according to the label, leave it the stated time, then scrub off with a stiff brush and rinse. A pressure washer can be used with care on sound dash, but keep the pressure low and the nozzle back: a strong jet will knock out stones and drive water into the render. After cleaning, let the walls dry out thoroughly. With a rough, porous surface that can take several dry days.

Step 3: Repair

• Cracks: rake out loose material and fill with a flexible exterior filler or a suitable mortar. Wider cracks may need cutting out and patching.
• Blown or missing patches: cut back to sound render, re-render the area and, while the new render is still wet, throw on matching stones. Getting the stone size and colour to match is hard, which is one reason painted pebble dash is easier to repair invisibly than unpainted.
• Sills, fascias and woodwork: fix any defects in the surrounding joinery at the same time.

Step 4: Stabilise

Old painted pebble dash is often chalky. Rub your hand across it: if it comes away coated in powder, apply a stabilising solution so the new paint bonds properly. Bare dash and new patches can be very absorbent, and many manufacturers recommend a thinned first coat or a primer. Follow the instructions for the paint system you are using.

Step 5: Choose the paint

Use an exterior masonry paint suited to rough surfaces. Textured or high-build masonry paints fill the uneven surface better and can bridge very fine cracks. Look for products described as resistant to algae and mould and suitable for exposed locations, which describes most of Kerry. Rough surfaces use far more paint than smooth render, so read the coverage rate on the tin with that in mind and buy enough from the same batch to finish each wall.

Step 6: Paint it

Timing

All the usual exterior painting rules apply: dry walls, a dry forecast, temperatures above the minimum on the tin, and avoiding strong direct sun and evening dew. Our guide to painting the outside of a house in Ireland covers timing in detail.

Tools

• Long-pile roller: a masonry roller with a long pile (often 25 mm or more) reaches into the gaps between stones. A roller extension pole saves a lot of ladder work.
• Masonry brush: a large, stiff brush to work paint into the texture and to cut in around windows and edges.
• Airless sprayer: much faster on large areas and gives good coverage into the texture, but everything not being painted (windows, doors, cars, plants, neighbouring walls) must be masked carefully, and overspray drifts in even a light breeze. Spraying is often followed by back-rolling to work the paint in.

Technique

1. Cut in around windows, doors and edges first with a brush.
2. Load the roller well and work in sections, rolling in different directions to push paint into every side of the stones.
3. Check from different angles for "holidays", the small missed spots in the shadows between stones that show up later as speckles of the old colour.
4. Keep a wet edge and finish a whole wall in one session where possible, breaking only at corners or natural lines.
5. Apply a second coat once the first is dry, as the tin directs. Two coats are nearly always needed on pebble dash.

Working safely

Painting walls means working at height. Follow the Health and Safety Authority guidance on ladders, use a scaffold tower or scaffolding for two-storey walls and long jobs, and never lean a ladder against a gutter. With airless sprayers, keep the tip away from skin; injection injuries from high-pressure paint are serious and need urgent medical attention.

Keeping it looking good

• Keep gutters and downpipes clear so water does not run down the walls; see how to clean gutters safely.
• Treat green growth early with a masonry wash rather than letting it build up.
• Cut back plants and climbers that keep walls damp.
• Touch up chips and cracks as they appear.

Painting and decorating is among the handyman services in County Kerry offered by Alpine Home Improvements if you would prefer to hand the job over.