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Exterior Cleaning > Projects > Full House Render Cleaning – Northampton (September 2024)

Full House Render Cleaning – Northampton (September 2024)

Clean modern residential property after professional render cleaning showing restored white walls and algae-free facade

Project overview
This residential property in Northampton had black algae staining across all facades, including the courtyard elevations and upper walls where moisture and run-off lines had left visible streaking. We carried out a full softwash render clean using a bleach-based treatment to break down the black biofilm, then finished with a biocide treatment to help slow regrowth.

Key details

  • Service: Full house render cleaning (softwash) + biocide treatment
  • Location: Northampton
  • Date: September 2024
  • Issue: Black algae staining on all elevations (front, sides, rear/courtyard)
  • Method: Bleach-based softwash (low pressure) + biocide finish

The problem

Black algae staining is common on lighter-coloured render and often shows as:

  • dark streaks under coping stones / parapets
  • marks around guttering and downpipes
  • heavier contamination on shaded or slower-drying elevations
  • patchy grey/black “film” across exposed walls

On this job, the staining was spread across every elevation, so the goal was a consistent clean finish—without damaging the render.

Our approach (softwash, not pressure washing)

We used a low-pressure softwash process designed for render surfaces:

  1. Pre-check & prep
    Visual inspection of the render, then protection of nearby areas as needed (doors, windows, sensitive points).
  2. Bleach-based softwash treatment
    A controlled application to break down and lift the black algae film from the surface.
  3. Second-pass on heavy growth
    The worst areas (typically run-off lines and damp/shaded zones) were treated again to remove remaining shadows.
  4. Low-pressure rinse
    Thorough rinse down to leave an even, clean appearance.
  5. Biocide treatment (finish step)
    Applied to help delay regrowth and keep the render cleaner for longer—especially useful on shaded elevations.

Results

  • Black algae staining removed across all facades, including courtyard walls
  • Render restored to a brighter, more even finish
  • Biocide applied for longer-lasting cleanliness and improved maintenance interval

Maintenance tips (to help it stay clean longer)

  • Keep gutters and downpipes flowing properly to reduce streaking and damp run-off lines
  • Improve airflow by trimming back vegetation near walls where possible
  • Consider a maintenance biocide top-up on the most shaded elevations over time

Project images

Stained house render facade showing black algae growth on upper walls before professional softwash cleaning treatment
Before: Upper facade showing black algae contamination before softwash treatment
Residential gable end wall showing severe black algae staining and discoloration before professional render cleaning service
Before: Gable end with heavy algae growth requiring softwash treatment
House render wall during cleaning showing partial algae removal with contrast between treated and untreated areas
During: Bleach-based softwash treatment showing immediate algae removal results
Multi-story residential property courtyard showing algae-stained render walls before professional cleaning and biocide application
Before: Courtyard view showing algae staining on all facades, Northampton 2024
Clean modern residential property after professional render cleaning showing restored white walls and algae-free facade
After: Complete house render cleaning with long-term biocide protection applied
Clean residential house render after professional softwash cleaning showing restored beige exterior walls and blue garage doors in Northampton
After: Professional house render cleaning completed using softwash treatment in Northampton, 2024-09
Final view of clean residential property from driveway showing completed render cleaning with algae-free walls and biocide protection
After: Final result showing complete render restoration, Northampton September 2024
Clean residential garage doors and render walls after professional cleaning showing ground-level view of completed work
After: Garage area with clean render walls and restored appearance
Clean residential courtyard showing professionally cleaned render walls with restored appearance after algae removal and biocide application
After: Courtyard showing complete algae removal and restored render appearance
Clean residential gutters and render wall after professional algae removal showing restored white appearance and biocide protection
After: Clean gutters and render wall following biocide treatment, Northampton
Dirty house render showing black algae staining and discoloration on white walls before professional cleaning service
Before: House render with black algae staining requiring professional cleaning, Northampton
render cleaning 3 storey multiple houses
Render cleaning 3 storey multiple houses
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