painting

How to Paint Exterior Masonry: Preparation, Products and Application

Gabriel

16 Dec 2025 — 3 min read

Painting external masonry is a substantial but rewarding project that can transform the appearance of a house and provide meaningful weather protection to render and brickwork. Done well, a quality masonry paint system will last 8–12 years; done poorly, it peels within two years and leaves you facing the cost of stripping and starting again. The preparation phase determines almost everything about the long-term result.

Should You Paint Brick?

Before starting, consider whether painting is the right intervention. Unpainted brick is generally lower maintenance than painted brick — once painted, the brickwork needs repainting periodically and is difficult to return to bare brick without specialist chemical stripping. Painting historic brick can also affect planning or listed building consent requirements. For rendered houses (the majority of painted houses in the UK), painting is appropriate and expected maintenance.

Surface Preparation: The Critical Phase

Allow substantially more time for preparation than for painting itself — a 2:1 ratio is about right for a house that hasn't been painted before, and 1.5:1 for a repaint.

Cleaning

High-pressure washing (1,500–2,000 PSI) removes lichen, algae, moss, loose material and atmospheric deposits. Hire a pressure washer (around £40–60/day) or contract a cleaning service. Allow at least 48–72 hours for the surface to dry completely before painting — longer in cool weather. Painting over a damp surface is the single most common cause of premature failure.

For biological growth (lichen, algae, moss), apply a biocidal wash (Ronseal or Algon exterior surface cleaner) after pressure washing and allow to work for 24 hours. This kills remaining spores that washing doesn't remove — without it, biological growth returns much faster.

Repairs

All cracks, defective pointing, failed render, and damaged areas must be repaired before painting. Painting over cracks seals moisture in rather than out, accelerating deterioration. Fill cracks with exterior flexible filler (for hairlines and minor cracks) or cut out and re-render significant defects (see the separate article on render repairs). Repoint any areas where mortar is loose, crumbling or missing.

Any window frames, sills, door frames or metalwork should be masked or pre-painted before masonry painting begins — masonry paint on plastic or metal is very difficult to remove.

Choosing Masonry Paint

Smooth masonry paint (Dulux, Sandtex, Johnstone's Smooth): The most common choice. Good waterproofing, wide colour range, breathable formulation. Sandtex Ultra Smooth is a popular mid-range product; Dulux Weathershield Maximum Exposure is better for exposed or coastal properties. Coverage: 8–12m² per litre. Cost: £25–40 per 10L.
Textured (Tyrolean or roughcast) masonry paint: Contains fine aggregate for a textured finish that hides imperfections and provides additional thickness. Useful for rougher render surfaces. Applied by brush or roller but finish is harder to achieve uniformly by hand versus machine spray.
Elastomeric masonry paint: High-build, flexible product that bridges hairline cracks and provides excellent waterproofing. Mapei Elastocolor or K Rend Silicone TC — premium products for problem walls. Expensive (£50–80/10L) but justified for crack-prone render.
Mineral or silicone render (K Rend, Weber): Not paint but a thin coat system — applied more like a thin render than a paint. Durable, breathable, requires no maintenance for 20–25 years. Must be applied by a trained applicator — not a DIY product.

Priming

New or bare render, porous surfaces, or areas where previous paint has been removed need a stabilising primer coat before topcoat. Dulux Weathershield Stabilising Primer or equivalent — diluted 1:4 with water, applied liberally with a brush. This seals porous areas and prevents the topcoat being sucked into the substrate before it can form a film. Skipping the primer on porous surfaces means using significantly more topcoat and often getting a patchy result.

Application

Apply two full coats of masonry paint, allowing the first coat to dry thoroughly (typically 4–6 hours in warm weather, longer in cool or damp conditions) before applying the second. Work from top to bottom. Use a 230mm or 270mm roller with a 15–18mm pile (thicker pile for textured surfaces) for speed, cutting in at edges and around windows with a brush.

Don't thin masonry paint unless specified — it reduces coverage and waterproofing properties. Apply generously — thin coats on external masonry fail much faster than well-applied full coats.

Safety for Working at Height

For a two-storey house, a scaffold tower or hired podium scaffold is necessary for upper storey work. Domestic scaffolding hire costs £200–400/week for a standard semi. An alternative is a ground-anchored ladder platform with stabilisers, but this limits working area. Never extend beyond safe reach on a ladder — overreaching on a ladder is the cause of the majority of DIY-related falls.