How to Prepare Your Home's Exterior for Painting: The Full Checklist

Exterior painting is one of the most significant investments a homeowner can make in their property's appearance and protection. Done properly, a quality exterior decoration should last ten to fifteen years — but only if the preparation is right. Cut corners on preparation and the finest exterior paint in the world will fail within three to five years. Here is Hampstead Painting Company's complete exterior preparation checklist, used on every project we undertake across North London.

Before Any Paint Goes On: The Preparation Checklist

1. Inspection and Assessment

Every exterior painting project begins with a thorough inspection:

• Identify all areas of defective render — cracks, hollow areas (check by tapping), delamination, or areas where render is separating from the substrate
• Check pointing in brick areas — rake out and re-point any failed or open joints
• Inspect guttering and downpipes — clear all blockages, repair any leaks, ensure water is discharged away from the building
• Check windowsills, sills, and coping stones for cracks and failed sealant
• Inspect all external timber — fascias, soffits, sash window frames, door frames — for rot, failed putty, or loose sections

2. Cleaning the Surface

All exterior surfaces must be thoroughly cleaned before any preparation or painting work begins:

• High-pressure washing of all masonry and render — removes biological growth (algae, moss, lichen), loose material, and chalky degraded paint. Allow at least 48 hours for the surface to dry before proceeding.
• Application of a fungicidal biocide wash to surfaces with significant biological growth — this kills remaining spores and provides ongoing protection against regrowth
• Wire brushing of all loose, flaking, or blistered paint

3. Repairs

• Re-render all defective areas using appropriate render — lime-based on period properties, cement-based only on modern buildings or where the existing render is cement
• Fill hairline cracks with flexible exterior filler
• Re-bed loose windowsills and address any structural defects before painting
• Replace failed glazing putty and allow to cure for at least two weeks before painting
• Treat and prime any areas of rotten timber — cut out and splice if necessary

4. Priming

• Bare masonry: stabilising primer on any powdery or unstable areas
• New render patches: allow to cure fully (minimum 28 days for cement render) before applying masonry primer
• Bare timber: appropriate wood primer on all bare sections
• Bare metal: rust-inhibiting primer on all ironwork

5. Product Selection

Specify the correct exterior coating for the substrate — breathable mineral paint on lime render and traditional masonry; modern masonry paint on cement substrates. The wrong product can fail quickly regardless of preparation quality.

Hampstead Painting Company follows this preparation programme on every exterior project. Request a free survey and quote for your exterior decoration.